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1.
PLoS Pathog ; 17(10): e1009881, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34624065

RESUMO

Pathogenic bacteria rely on protein phosphorylation to adapt quickly to stress, including that imposed by the host during infection. Penicillin-binding protein and serine/threonine-associated (PASTA) kinases are signal transduction systems that sense cell wall integrity and modulate multiple facets of bacterial physiology in response to cell envelope stress. The PASTA kinase in the cytosolic pathogen Listeria monocytogenes, PrkA, is required for cell wall stress responses, cytosolic survival, and virulence, yet its substrates and downstream signaling pathways remain incompletely defined. We combined orthogonal phosphoproteomic and genetic analyses in the presence of a ß-lactam antibiotic to define PrkA phosphotargets and pathways modulated by PrkA. These analyses synergistically highlighted ReoM, which was recently identified as a PrkA target that influences peptidoglycan (PG) synthesis, as an important phosphosubstrate during cell wall stress. We find that deletion of reoM restores cell wall stress sensitivities and cytosolic survival defects of a ΔprkA mutant to nearly wild-type levels. While a ΔprkA mutant is defective for PG synthesis during cell wall stress, a double ΔreoM ΔprkA mutant synthesizes PG at rates similar to wild type. In a mouse model of systemic listeriosis, deletion of reoM in a ΔprkA background almost fully restored virulence to wild-type levels. However, loss of reoM alone also resulted in attenuated virulence, suggesting ReoM is critical at some points during pathogenesis. Finally, we demonstrate that the PASTA kinase/ReoM cell wall stress response pathway is conserved in a related pathogen, methicillin-resistant Staphylococcus aureus. Taken together, our phosphoproteomic analysis provides a comprehensive overview of the PASTA kinase targets of an important model pathogen and suggests that a critical role of PrkA in vivo is modulating PG synthesis through regulation of ReoM to facilitate cytosolic survival and virulence.


Assuntos
Parede Celular/fisiologia , Listeria monocytogenes/metabolismo , Listeria monocytogenes/patogenicidade , Peptidoglicano/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Listeriose/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Virulência
2.
Proc Natl Acad Sci U S A ; 118(39)2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34544876

RESUMO

Aspergillus fumigatus is a human opportunistic pathogen showing emerging resistance against a limited repertoire of antifungal agents available. The GTPase Rho1 has been identified as an important regulator of the cell wall integrity signaling pathway that regulates the composition of the cell wall, a structure that is unique to fungi and serves as a target for antifungal compounds. Rom2, the guanine nucleotide exchange factor to Rho1, contains a C-terminal citron homology (CNH) domain of unknown function that is found in many other eukaryotic genes. Here, we show that the Rom2 CNH domain interacts directly with Rho1 to modulate ß-glucan and chitin synthesis. We report the structure of the Rom2 CNH domain, revealing that it adopts a seven-bladed ß-propeller fold containing three unusual loops. A model of the Rho1-Rom2 CNH complex suggests that the Rom2 CNH domain interacts with the Rho1 Switch II motif. This work uncovers the role of the Rom2 CNH domain as a scaffold for Rho1 signaling in fungal cell wall biosynthesis.


Assuntos
Aspergillus fumigatus/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Parede Celular/fisiologia , Proteínas Fúngicas/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Aspergillus fumigatus/genética , Aspergillus fumigatus/crescimento & desenvolvimento , Fatores de Transcrição de Zíper de Leucina Básica/química , Fatores de Transcrição de Zíper de Leucina Básica/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/genética , Conformação Proteica , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais , Proteínas rho de Ligação ao GTP/química , Proteínas rho de Ligação ao GTP/genética
3.
Int J Mol Sci ; 22(16)2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34445724

RESUMO

Plant height is one of the most important agronomic traits of rapeseeds. In this study, we characterized a dwarf Brassica napus mutant, named ndf-2, obtained from fast neutrons and DES mutagenesis. Based on BSA-Seq and genetic properties, we identified causal mutations with a time-saving approach. The ndf-2 mutation was identified on chromosome A03 and can result in an amino acid substitution in the conserved degron motif (GWPPV to EWPPV) of the Auxin/indole-3-acetic acid protein 7 (BnaA03.IAA7) encoded by the causative gene. Aux/IAA protein is one of the core components of the auxin signaling pathway, which regulates many growth and development processes. However, the molecular mechanism of auxin signal regulating plant height is still not well understood. In the following work, we identified that BnaARF6 and BnaARF8 as interactors of BnaA03.IAA7 and BnaEXPA5 as a target of BnaARF6 and BnaARF8. The three genes BnaA03.IAA7, BnaARF6/8 and BnaEXPA5 were highly expressed in stem, suggesting that these genes were involved in stem development. The overexpression of BnaEXPA5 results in larger rosettes leaves and longer inflorescence stems in Arabidopsis thaliana. Our results indicate that BnaA03.IAA7- and BnaARF6/8-dependent auxin signal control stem elongation and plant height by regulating the transcription of BnaEXPA5 gene, which is one of the targets of this signal.


Assuntos
Brassica napus/genética , Parede Celular/fisiologia , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Caules de Planta/crescimento & desenvolvimento , Arabidopsis , Brassica napus/crescimento & desenvolvimento , Brassica napus/metabolismo , Mutação com Ganho de Função , Ácidos Indolacéticos/metabolismo , Proteínas de Plantas/metabolismo
4.
Nat Plants ; 7(6): 826-841, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34112988

RESUMO

The leaf epidermis is a dynamic biomechanical shell that integrates growth across spatial scales to influence organ morphology. Pavement cells, the fundamental unit of this tissue, morph irreversibly into highly lobed cells that drive planar leaf expansion. Here, we define how tissue-scale cell wall tensile forces and the microtubule-cellulose synthase systems dictate the patterns of interdigitated growth in real time. A morphologically potent subset of cortical microtubules span the periclinal and anticlinal cell faces to pattern cellulose fibres that generate a patch of anisotropic wall. The subsequent local polarized growth is mechanically coupled to the adjacent cell via a pectin-rich middle lamella, and this drives lobe formation. Finite element pavement cell models revealed cell wall tensile stress as an upstream patterning element that links cell- and tissue-scale biomechanical parameters to interdigitated growth. Cell lobing in leaves is evolutionarily conserved, occurs in multiple cell types and is associated with important agronomic traits. Our general mechanistic models of lobe formation provide a foundation to analyse the cellular basis of leaf morphology and function.


Assuntos
Arabidopsis/citologia , Células Vegetais , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Arabidopsis/crescimento & desenvolvimento , Fenômenos Biomecânicos , Forma Celular , Parede Celular/fisiologia , Celulose/metabolismo , Análise de Elementos Finitos , Microscopia Eletrônica de Transmissão , Microtúbulos/metabolismo , Modelos Biológicos , Mutação , Células Vegetais/metabolismo , Plantas Geneticamente Modificadas , Plasmodesmos
5.
BMC Plant Biol ; 21(1): 251, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34078286

RESUMO

BACKGROUND: Besides the use of maize grain as food and feed, maize stover can be a profitable by-product for cellulosic ethanol production, whereas the whole plant can be used for silage production. However, yield is reduced by pest damages, stem corn borers being one of the most important yield constraints. Overall, cell wall composition is key in determining the quality of maize biomass, as well as pest resistance. This study aims to evaluate the composition of the four cell wall fractions (cellulose, hemicellulose, lignin and hydroxycinnamates) in diverse maize genotypes and to understand how this composition influences the resistance to pests, ethanol capacity and digestibility. RESULTS: The following results can be highlighted: (i) pests' resistant materials may show cell walls with low p-coumaric acid and low hemicellulose content; (ii) inbred lines showing cell walls with high cellulose content and high diferulate cross-linking may present higher performance for ethanol production; (iii) and inbreds with enhanced digestibility may have cell walls poor in neutral detergent fibre and diferulates, combined with a lignin polymer composition richer in G subunits. CONCLUSIONS: Results evidence that there is no maize cell wall ideotype among the tested for optimal performance for various uses, and maize plants should be specifically bred for each particular application.


Assuntos
Parede Celular/química , Endogamia , Zea mays/genética , Zea mays/fisiologia , Parede Celular/fisiologia , Celulose/química , Celulose/metabolismo , Ácidos Cumáricos , Lignina/química , Lignina/metabolismo , Polissacarídeos/química , Polissacarídeos/metabolismo
6.
J Invertebr Pathol ; 184: 107639, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34139258

RESUMO

Beauveria bassiana is an important entomopathogenic fungus used to control a variety of insect pests. Conidia are the infective propagules of the fungus. However, some important factors that influence conidiation are still to be investigated. In this study, a mutant with decreased conidial production and hyphal growth was identified from a random T-DNA insertional library of B. bassiana. The corresponding gene (Bbthi) for this mutation encodes a putative thiazole synthase. Thiazole and pyrimidine are structural components of thiamine (vitamin B1), which is an essential nutrient for all forms of life. Disruption of Bbthi, Bbpyr, a putative pyrimidine synthetic gene, or both in B. bassiana results in a significant decrease of thiamine content. Loss of Bbthi and Bbpyr function significantly decreased the conidial production and hyphal growth, as well as disrupted the integrity of conidial cell wall. However, the defect of Bbpyr and Bbthi does not decrease the virulence of B. bassiana. Our results indicate the importance of thiamine biosynthesis in conidiation of B. bassiana, and provide useful information to produce conidia of entomopathogenic fungi for biocontrol of insect pests.


Assuntos
Beauveria/genética , Proteínas Fúngicas/genética , Genes Fúngicos/fisiologia , Esporos Fúngicos/fisiologia , Tiamina/biossíntese , Beauveria/metabolismo , Parede Celular/fisiologia , Proteínas Fúngicas/metabolismo , Tiamina/genética
7.
Science ; 372(6543): 706-711, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33986175

RESUMO

Plants have evolved complex nanofibril-based cell walls to meet diverse biological and physical constraints. How strength and extensibility emerge from the nanoscale-to-mesoscale organization of growing cell walls has long been unresolved. We sought to clarify the mechanical roles of cellulose and matrix polysaccharides by developing a coarse-grained model based on polymer physics that recapitulates aspects of assembly and tensile mechanics of epidermal cell walls. Simple noncovalent binding interactions in the model generate bundled cellulose networks resembling that of primary cell walls and possessing stress-dependent elasticity, stiffening, and plasticity beyond a yield threshold. Plasticity originates from fibril-fibril sliding in aligned cellulose networks. This physical model provides quantitative insight into fundamental questions of plant mechanobiology and reveals design principles of biomaterials that combine stiffness with yielding and extensibility.


Assuntos
Parede Celular/fisiologia , Parede Celular/ultraestrutura , Celulose , Células Vegetais/ultraestrutura , Epiderme Vegetal/ultraestrutura , Polissacarídeos , Fenômenos Biomecânicos , Configuração de Carboidratos , Celulose/química , Elasticidade , Modelos Biológicos , Simulação de Dinâmica Molecular , Cebolas/ultraestrutura , Estresse Mecânico
8.
Int J Mol Sci ; 22(6)2021 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-33806816

RESUMO

Cell wall biosynthesis is a complex biological process in plants. In the rapidly growing cells or in the plants that encounter a variety of environmental stresses, the compositions and the structure of cell wall can be dynamically changed. To constantly monitor cell wall status, plants have evolved cell wall integrity (CWI) maintenance system, which allows rapid cell growth and improved adaptation of plants to adverse environmental conditions without the perturbation of cell wall organization. Salt stress is one of the abiotic stresses that can severely disrupt CWI, and studies have shown that the ability of plants to sense and maintain CWI is important for salt tolerance. In this review, we highlight the roles of CWI in salt tolerance and the mechanisms underlying the maintenance of CWI under salt stress. The unsolved questions regarding the association between the CWI and salt tolerance are discussed.


Assuntos
Parede Celular/fisiologia , Fenômenos Fisiológicos Vegetais , Salinidade , Tolerância ao Sal , Adaptação Fisiológica , Celulose/biossíntese , Regulação da Expressão Gênica de Plantas , Glicoproteínas/metabolismo , Concentração de Íons de Hidrogênio , Espaço Intracelular/metabolismo , Oxirredução , Transdução de Sinais
9.
Plant Sci ; 307: 110882, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33902850

RESUMO

Lodging is one of the causes of maize (Zea mays L.) production losses worldwide and, at least, the resistance to stalk lodging has been positively correlated with stalk strength. In order to elucidate the putative relationship between cell wall, stalk strength and lodging resistance, twelve maize inbreds varying in rind penetration strength and lodging resistance were characterized for cell wall composition and structure. Stepwise multiple regression indicates that H lignin subunits confer a greater rind penetration strength. Besides, the predictive model for lodging showed that a high ferulic acid content increases the resistance to lodging, whereas those of diferulates decrease it. These outcomes highlight that the strength and lodging susceptibility of maize stems may be conditioned by structural features of cell wall rather than by the net amount of cellulose, hemicelluloses and lignin. The results presented here provide biotechnological targets in breeding programs aimed at improving lodging in maize.


Assuntos
Parede Celular/química , Parede Celular/fisiologia , Caules de Planta/química , Caules de Planta/crescimento & desenvolvimento , Zea mays/química , Zea mays/crescimento & desenvolvimento , Zea mays/genética , Parede Celular/genética , Produtos Agrícolas/química , Produtos Agrícolas/genética , Produtos Agrícolas/crescimento & desenvolvimento , Resistência à Doença/genética , Resistência à Doença/fisiologia , Variação Genética , Genótipo , Fenótipo , Caules de Planta/genética
10.
Int J Mol Sci ; 22(7)2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-33808132

RESUMO

The secondary wall is the main part of wood and is composed of cellulose, xylan, lignin, and small amounts of structural proteins and enzymes. Lignin molecules can interact directly or indirectly with cellulose, xylan and other polysaccharide molecules in the cell wall, increasing the mechanical strength and hydrophobicity of plant cells and tissues and facilitating the long-distance transportation of water in plants. MYBs (v-myb avian myeloblastosis viral oncogene homolog) belong to one of the largest superfamilies of transcription factors, the members of which regulate secondary cell-wall formation by promoting/inhibiting the biosynthesis of lignin, cellulose, and xylan. Among them, MYB46 and MYB83, which comprise the second layer of the main switch of secondary cell-wall biosynthesis, coordinate upstream and downstream secondary wall synthesis-related transcription factors. In addition, MYB transcription factors other than MYB46/83, as well as noncoding RNAs, hormones, and other factors, interact with one another to regulate the biosynthesis of the secondary wall. Here, we discuss the biosynthesis of secondary wall, classification and functions of MYB transcription factors and their regulation of lignin polymerization and secondary cell-wall formation during wood formation.


Assuntos
Parede Celular/fisiologia , Lignina/biossíntese , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Xilema/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Lignina/metabolismo , Reguladores de Crescimento de Plantas/genética , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Fatores de Transcrição/genética , Madeira/crescimento & desenvolvimento , Xilema/metabolismo
11.
Yeast ; 38(8): 480-492, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33913187

RESUMO

Variations in cell wall composition and biomechanical properties can contribute to the cellular plasticity required during complex processes such as polarized growth and elongation in microbial cells. This study utilizes atomic force microscopy (AFM) to map the cell surface topography of fission yeast, Schizosaccharomyces pombe, at the pole regions and to characterize the biophysical properties within these regions under physiological, hydrated conditions. High-resolution images acquired from AFM topographic scanning reveal decreased surface roughness at the cell poles. Force extension curves acquired by nanoindentation probing with AFM cantilever tips under low applied force revealed increased cell wall deformation and decreased cellular stiffness (cellular spring constant) at cell poles (17 ± 4 mN/m) relative to the main body of the cell that is not undergoing growth and expansion (44 ± 10 mN/m). These findings suggest that the increased deformation and decreased stiffness at regions of polarized growth at fission yeast cell poles provide the plasticity necessary for cellular extension. This study provides a direct biophysical characterization of the S. pombe cell surface by AFM, and it provides a foundation for future investigation of how the surface topography and local nanomechanical properties vary during different cellular processes.


Assuntos
Membrana Celular/fisiologia , Parede Celular/ultraestrutura , Microscopia de Força Atômica/métodos , Schizosaccharomyces/fisiologia , Schizosaccharomyces/ultraestrutura , Membrana Celular/ultraestrutura , Parede Celular/química , Parede Celular/fisiologia , Schizosaccharomyces/crescimento & desenvolvimento
12.
J Invertebr Pathol ; 181: 107588, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33862054

RESUMO

Fungal polyketide synthases play important and differential roles in synthesizing secondary metabolites and regulating several cell events, including asexual development, environmental adaptation, and pathogenicity. This study shows the important functions of a highly reducing polyketide synthase, Pks11, in Beauveria bassiana, a filamentous fungal insect pathogen used worldwide for pest biocontrol. The deletion of pks11 led to severe defects in conidial yields on different media and a decrease of 36.27% in the mean thickness of conidial cell wall under normal conditions. Compared with the wild-type, Δpks11 showed higher tolerance to oxidation and increased sensitivity to high temperature during colony growth. Moreover, the lack of pks11 caused a decrease in conidial germination after exposure to UV radiation but did not affect the virulence of B. bassiana against Galleria mellonella larvae via typical cuticle infection. These findings concurred with the alteration in the transcript levels of some phenotype-related genes. These data suggested that pks11 played vital roles in the asexual development, cell wall integrity, and fungal responses to oxidation, high temperature, and UV irradiation of B. bassiana.


Assuntos
Beauveria/genética , Proteínas Fúngicas/genética , Policetídeo Sintases/genética , Tolerância a Radiação/genética , Esporos Fúngicos/genética , Raios Ultravioleta/efeitos adversos , Beauveria/enzimologia , Beauveria/fisiologia , Beauveria/efeitos da radiação , Parede Celular/fisiologia , Proteínas Fúngicas/metabolismo , Policetídeo Sintases/metabolismo , Esporos Fúngicos/fisiologia , Esporos Fúngicos/efeitos da radiação
13.
Plant Cell Physiol ; 62(1): 53-65, 2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33764471

RESUMO

Secondary wall deposition in xylem vessels is activated by Vascular-Related NAC Domain proteins (VNDs) that belong to a group of secondary wall NAC (SWN) transcription factors. By contrast, Xylem NAC Domain1 (XND1) negatively regulates secondary wall deposition in xylem vessels when overexpressed. The mechanism by which XND1 exerts its functions remains elusive. We employed the promoter of the fiber-specific Secondary Wall-Associated NAC Domain1 (SND1) gene to ectopically express XND1 in fiber cells to investigate its mechanism of action on secondary wall deposition. Ectopic expression of XND1 in fiber cells severely diminished their secondary wall deposition and drastically reduced the expression of SWN-regulated downstream transcription factors and secondary wall biosynthetic genes but not that of the SWN genes themselves. Transactivation analyses revealed that XND1 specifically inhibited SWN-activated expression of these downstream genes but not their MYB46-activated expression. Both the NAC domain and the C-terminus of XND1 were required for its inhibitory function and its NAC domain interacted with the DNA-binding domains of SWNs. XND1 was shown to be localized in the cytoplasm and the nucleus and its co-expression with VND6 resulted in the cytoplasmic sequestration of VND6. Furthermore, the C-terminus of XND1 was indispensable for the XND1-mediated cytoplasmic retention of VND6 and its fusion to VND6 was able to direct VND6 to the cytoplasm and render it unable to activate the gene expression. Since the XND1 gene is specifically expressed in xylem cells, these results indicate that XND1 acts through inhibiting VND functions to negatively regulate secondary wall deposition in xylem vessels.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Proteínas de Ligação a DNA/fisiologia , Fatores de Transcrição/fisiologia , Xilema/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Parede Celular/metabolismo , Parede Celular/fisiologia , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Fatores de Transcrição/metabolismo , Xilema/fisiologia
14.
PLoS Pathog ; 17(3): e1009468, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33788901

RESUMO

Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease.


Assuntos
Parede Celular/fisiologia , Interações Hospedeiro-Patógeno/fisiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/patogenicidade , Virulência/fisiologia , Animais , Camundongos , Peptidoglicano/metabolismo , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/metabolismo , Peixe-Zebra
15.
mBio ; 12(2)2021 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-33727349

RESUMO

Filamentous fungi undergo somatic cell fusion to create a syncytial, interconnected hyphal network which confers a fitness benefit during colony establishment. However, barriers to somatic cell fusion between genetically different cells have evolved that reduce invasion by parasites or exploitation by maladapted genetic entities (cheaters). Here, we identified a predicted mannosyltransferase, glycosyltransferase family 69 protein (GT69-2) that was required for somatic cell fusion in Neurospora crassa Cells lacking GT69-2 prematurely ceased chemotropic signaling and failed to complete cell wall dissolution and membrane merger in pairings with wild-type cells or between Δgt69-2 cells (self fusion). However, loss-of-function mutations in the linked regulator of cell fusion and cell wall remodeling-1 (rfw-1) locus suppressed the self-cell-fusion defects of Δgt69-2 cells, although Δgt69-2 Δrfw-1 double mutants still failed to undergo fusion with wild-type cells. Both GT69-2 and RFW-1 localized to the Golgi apparatus. Genetic analyses indicated that RFW-1 negatively regulates cell wall remodeling-dependent processes, including cell wall dissolution during cell fusion, separation of conidia during asexual sporulation, and conidial germination. GT69-2 acts as an antagonizer to relieve or prevent negative functions on cell fusion by RFW-1. In Neurospora species and N. crassa populations, alleles of gt69-2 were highly polymorphic and fell into two discrete haplogroups. In all isolates within haplogroup I, rfw-1 was conserved and linked to gt69-2 All isolates within haplogroup II lacked rfw-1. These data indicated that gt69-2/rfw-1 are under balancing selection and provide new mechanisms regulating cell wall remodeling during cell fusion and conidial separation.IMPORTANCE Cell wall remodeling is a dynamic process that balances cell wall integrity versus cell wall dissolution. In filamentous fungi, cell wall dissolution is required for somatic cell fusion and conidial separation during asexual sporulation. In the filamentous fungus Neurospora crassa, allorecognition checkpoints regulate the cell fusion process between genetically different cells. Our study revealed two linked loci with transspecies polymorphisms and under coevolution, rfw-1 and gt69-2, which form a coordinated system to regulate cell wall remodeling during somatic cell fusion, conidial separation, and asexual spore germination. RFW-1 acts as a negative regulator of these three processes, while GT69-2 functions antagonistically to RFW-1. Our findings provide new insight into the mechanisms involved in regulation of fungal cell wall remodeling during growth and development.


Assuntos
Parede Celular/fisiologia , Regulação Fúngica da Expressão Gênica , Manosiltransferases/genética , Manosiltransferases/metabolismo , Neurospora crassa/enzimologia , Neurospora crassa/genética , Parede Celular/genética , Genes Fúngicos , Hifas/fisiologia , Mutação , Neurospora crassa/fisiologia , Transdução de Sinais , Esporos Fúngicos/metabolismo
16.
Arch Microbiol ; 203(5): 2147-2155, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33611635

RESUMO

Enterococcus faecalis (E. faecalis) is an indigenous intestinal bacterium and has potential to be applied as probiotic supplement. Low pH is one of the main stresses that E. faecalis has to deal with to colonize in the gastrointestinal tract. Previous study indicated low concentration of flavonoids may enhance the tolerance of probiotic to environmental stress. In the present research, transcriptome analysis was employed to investigate the influence of Cyclocarya paliurus flavonoids (CPF) on E. faecalis exposed to low pH environment. The results revealed that under the stress of low pH, genes related to cell wall and membrane, transmembrane transport, metabolism process, energy production, and conversion stress proteins were significantly differentially expressed. And certain undesired changes of which (such as genes for MFS transporter were downregulated) could be partially mitigated by CPF intervention, indicating their capacity to improve the low pH tolerance of E. faecalis. Results from this study deepened our understanding of the beneficial role of CPF on the probiotic in the gastrointestinal environment.


Assuntos
Transporte Biológico/genética , Enterococcus faecalis/metabolismo , Flavonoides/metabolismo , Juglandaceae/metabolismo , Estresse Fisiológico/fisiologia , Parede Celular/fisiologia , Regulação para Baixo , Enterococcus faecalis/genética , Perfilação da Expressão Gênica , Concentração de Íons de Hidrogênio , Intestinos/microbiologia , Juglandaceae/genética , Probióticos/metabolismo , Transcriptoma/genética
17.
Lett Appl Microbiol ; 72(5): 604-609, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33539564

RESUMO

Methicillin-resistant Staphylococcus aureus (MRSA) with reduced sensitivity to vancomycin (VAN) has caused many clinical cases of VAN treatment failure, but the molecular mechanism underlying the reduced sensitivity to VAN is still unclear. We isolated a heterogeneous VAN-intermediate Staphylococcus aureus (hVISA), which was also a MRSA strain with reduced sensitivity to VAN. To investigate the molecular mechanism underlying the reduced sensitivity to VAN exhibited by the hVISA strain, we compared the hVISA strain with a VAN-sensitive MRSA strain, known as the N315 strain. The images captured by transmission electron microscopy showed that the cell wall of the hVISA strain was significantly thicker than that of the N315 strain (36·72 ± 1·04 nm vs 28·15 ± 1·25 nm, P < 0·05), and the results of real-time quantitative PCR analysis suggested that the expression levels of the cell wall thickness related genes (glmS, vraR/S, sgtB, murZ and PBP4) of the hVISA strain were significantly higher than those of the N315 strain (P < 0·05). In conclusion, this study indicated that the upregulation of the expression of the genes related to cell wall synthesis might be the molecular mechanism underlying the cell wall thickening of the hVISA strain and might be related to its resistance to VAN.


Assuntos
Parede Celular/metabolismo , Parede Celular/fisiologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Resistência a Vancomicina/genética , Staphylococcus aureus Resistente à Vancomicina/crescimento & desenvolvimento , Antibacterianos/farmacologia , Regulação Bacteriana da Expressão Gênica/genética , Humanos , Meticilina/farmacologia , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/tratamento farmacológico , Regulação para Cima/genética , Vancomicina/farmacologia
18.
Nat Rev Microbiol ; 19(7): 454-466, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33558691

RESUMO

Cryptococcus spp., in particular Cryptococcus neoformans and Cryptococcus gattii, have an enormous impact on human health worldwide. The global burden of cryptococcal meningitis is almost a quarter of a million cases and 181,000 deaths annually, with mortality rates of 100% if infections remain untreated. Despite these alarming statistics, treatment options for cryptococcosis remain limited, with only three major classes of drugs approved for clinical use. Exacerbating the public health burden is the fact that the only new class of antifungal drugs developed in decades, the echinocandins, displays negligible antifungal activity against Cryptococcus spp., and the efficacy of the remaining therapeutics is hampered by host toxicity and pathogen resistance. Here, we describe the current arsenal of antifungal agents and the treatment strategies employed to manage cryptococcal disease. We further elaborate on the recent advances in our understanding of the intrinsic and adaptive resistance mechanisms that are utilized by Cryptococcus spp. to evade therapeutic treatments. Finally, we review potential therapeutic strategies, including combination therapy, the targeting of virulence traits, impairing stress response pathways and modulating host immunity, to effectively treat infections caused by Cryptococcus spp. Overall, understanding of the mechanisms that regulate anti-cryptococcal drug resistance, coupled with advances in genomics technologies and high-throughput screening methodologies, will catalyse innovation and accelerate antifungal drug discovery.


Assuntos
Criptococose/tratamento farmacológico , Cryptococcus/citologia , Cryptococcus/fisiologia , Antifúngicos/farmacologia , Parede Celular/química , Parede Celular/fisiologia , Criptococose/imunologia , Criptococose/microbiologia , Cryptococcus/química , Cryptococcus/efeitos dos fármacos , Farmacorresistência Fúngica , Equinocandinas/farmacologia , Cápsulas Fúngicas/química , Cápsulas Fúngicas/fisiologia , Polissacarídeos Fúngicos/química , Fatores de Virulência
19.
Sci Rep ; 11(1): 3653, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33574466

RESUMO

The sporangiophores of Phycomyces blakesleeanus have been used as a model system to study sensory transduction, helical growth, and to establish global biophysical equations for expansive growth of walled cells. More recently, local statistical biophysical models of the cell wall are being constructed to better understand the molecular underpinnings of helical growth and its behavior during the many growth responses of the sporangiophores to sensory stimuli. Previous experimental and theoretical findings guide the development of these local models. Future development requires an investigation of explicit and implicit assumptions made in the prior research. Here, experiments are conducted to test three assumptions made in prior research, that (a) elongation rate, (b) rotation rate, and (c) helical growth steepness, R, of the sporangiophore remain constant during the phototropic response (bending toward unilateral light) and the avoidance response (bending away from solid barriers). The experimental results reveal that all three assumptions are incorrect for the phototropic response and probably incorrect for the avoidance response but the results are less conclusive. Generally, the experimental results indicate that the elongation and rotation rates increase during these responses, as does R, indicating that the helical growth steepness become flatter. The implications of these findings on prior research, the "fibril reorientation and slippage" hypothesis, global biophysical equations, and local statistical biophysical models are discussed.


Assuntos
Biofísica/tendências , Gravitropismo/fisiologia , Fototropismo/fisiologia , Phycomyces/crescimento & desenvolvimento , Fenômenos Biológicos , Parede Celular/fisiologia , Parede Celular/efeitos da radiação , Gravitropismo/efeitos da radiação , Luz , Modelos Biológicos , Fototropismo/efeitos da radiação , Phycomyces/efeitos da radiação
20.
PLoS Comput Biol ; 17(1): e1007971, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33507956

RESUMO

Many cellular processes require cell polarization to be maintained as the cell changes shape, grows or moves. Without feedback mechanisms relaying information about cell shape to the polarity molecular machinery, the coordination between cell polarization and morphogenesis, movement or growth would not be possible. Here we theoretically and computationally study the role of a genetically-encoded mechanical feedback (in the Cell Wall Integrity pathway) as a potential coordination mechanism between cell morphogenesis and polarity during budding yeast mating projection growth. We developed a coarse-grained continuum description of the coupled dynamics of cell polarization and morphogenesis as well as 3D stochastic simulations of the molecular polarization machinery in the evolving cell shape. Both theoretical approaches show that in the absence of mechanical feedback (or in the presence of weak feedback), cell polarity cannot be maintained at the projection tip during growth, with the polarization cap wandering off the projection tip, arresting morphogenesis. In contrast, for mechanical feedback strengths above a threshold, cells can robustly maintain cell polarization at the tip and simultaneously sustain mating projection growth. These results indicate that the mechanical feedback encoded in the Cell Wall Integrity pathway can provide important positional information to the molecular machinery in the cell, thereby enabling the coordination of cell polarization and morphogenesis.


Assuntos
Polaridade Celular/fisiologia , Retroalimentação Fisiológica/fisiologia , Modelos Biológicos , Morfogênese/fisiologia , Fenômenos Biomecânicos/fisiologia , Movimento Celular/fisiologia , Parede Celular/fisiologia , Biologia Computacional , Simulação por Computador , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Proteína cdc42 de Saccharomyces cerevisiae de Ligação ao GTP/metabolismo
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