Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Dev Cell ; 56(18): 2592-2606.e7, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34508658

RESUMO

Membrane contact between intracellular organelles is important in mediating organelle communication. However, the assembly of molecular machinery at membrane contact site and its internal organization correlating with its functional activity remain unclear. Here, we demonstrate that a gel-like condensation of Cidec, a crucial protein for obesity development by facilitating lipid droplet (LD) fusion, occurs at the LD-LD contact site (LDCS) through phase separation. The homomeric interaction between the multivalent N terminus of Cidec is sufficient to promote its phase separation both in vivo and in vitro. Interestingly, Cidec condensation at LDCSs generates highly plastic and lipid-permeable fusion plates that are geometrically constrained by donor LDs. In addition, Cidec condensates are distributed unevenly in the fusion plate generating stochastic sub-compartments that may represent unique lipid passageways during LD fusion. We have thus uncovered the organization and functional significance of geometry-constrained Cidec phase separation in mediating LD fusion and lipid homeostasis.

2.
Cell Metab ; 33(8): 1655-1670.e8, 2021 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-34015269

RESUMO

How amphipathic phospholipids are shuttled between the membrane bilayer remains an essential but elusive process, particularly at the endoplasmic reticulum (ER). One prominent phospholipid shuttling process concerns the biogenesis of APOB-containing lipoproteins within the ER lumen, which may require bulk trans-bilayer movement of phospholipids from the cytoplasmic leaflet of the ER bilayer. Here, we show that TMEM41B, present in the lipoprotein export machinery, encodes a previously conceptualized ER lipid scramblase mediating trans-bilayer shuttling of bulk phospholipids. Loss of hepatic TMEM41B eliminates plasma lipids, due to complete absence of mature lipoproteins within the ER, but paradoxically also activates lipid production. Mechanistically, scramblase deficiency triggers unique ER morphological changes and unsuppressed activation of SREBPs, which potently promotes lipid synthesis despite stalled secretion. Together, this response induces full-blown nonalcoholic hepatosteatosis in the TMEM41B-deficient mice within weeks. Collectively, our data uncovered a fundamental mechanism safe-guarding ER function and integrity, dysfunction of which disrupts lipid homeostasis.

3.
Traffic ; 21(1): 94-105, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31746121

RESUMO

Dysregulation of lipid homeostasis leads to the development of metabolic disorders including obesity, diabetes, cardiovascular disease and cancer. Lipid droplets (LDs) are subcellular organelles vital in the maintenance of lipid homeostasis by coordinating lipid synthesis, lipid storage, lipid secretion and lipolysis. Under fed condition, free fatty acids (FFAs) are remodeled and esterified into neutral lipids by lipogenesis and stored in the LDs. The lipid storage capacity of LDs is controlled by its growth via local lipid synthesis or by LD fusion. During fasting, neutral lipids are hydrolyzed by lipolysis, released as FFAs and secreted to meet energy demand. Cell death-inducing DNA fragmentation factor alpha (DFFA)-like effector (CIDE) family proteins composed of Cidea, Cideb and Cidec/Fsp27 are ER- and LD-associated proteins and have emerged as important regulators of lipid homeostasis. Notably, when localized on the LDs, CIDE proteins enrich at the LD-LD contact sites (LDCSs) and control LD fusion and growth. Here, we summarize these recent advances made on the role of CIDE proteins in the regulation of lipid metabolism with a particular focus on the molecular mechanisms underlying CIDE-mediated LD fusion and growth.


Assuntos
Proteínas Reguladoras de Apoptose , Doenças Metabólicas , Proteínas Reguladoras de Apoptose/metabolismo , Homeostase , Humanos , Gotículas Lipídicas/metabolismo , Metabolismo dos Lipídeos , Doenças Metabólicas/metabolismo
4.
Arch Biochem Biophys ; 671: 167-174, 2019 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-31295433

RESUMO

In Saccharomyces cerevisiae, Sir proteins mediate heterochromatin epigenetic gene silencing. The assembly of silent heterochromatin requires histone deacetylation by Sir2, conformational change of SIR complexes, and followed by spreading of SIR complexes along the chromatin fiber to form extended silent heterochromatin domains. Sir2 couples histone deacetylation and NAD hydrolysis to generate an epigenetic metabolic small molecule, O-acetyl-ADP-ribose (AAR). Here, we demonstrate that AAR physically associates with Sir3 and that polySir3-AAR formation has a specific and essential role in the assembly of silent SIR-nucleosome pre-heterochromatin filaments. Furthermore, we show that AAR is capable of stabilizing binding of the Sir3 BAH domain to the Sir3 carboxyl-terminal region. Our data suggests that for the assembly of SIR-nucleosome pre-heterochromatin filament, the structural rearrangement of SIR-nucleosome is important and result in creating more stable interactions of Sir3, such as the inter-molecule Sir3-Sir3 interaction, and the Sir3-nucleosome interaction within the filaments. In conclusion, our results reveal the importance of AAR, indicating that it not only affects the conformational rearrangement of SIR complexes but also might function as a critical fine-tuning modulatory component of yeast silent SIR-nucleosome pre-heterochromatin by stabilizing the intermolecular interaction between Sir3 N- and C-terminal regions.


Assuntos
Heterocromatina/metabolismo , Nucleossomos/metabolismo , O-Acetil-ADP-Ribose/metabolismo , Proteínas Reguladoras de Informação Silenciosa de Saccharomyces cerevisiae/metabolismo , Epigênese Genética , Ligação Proteica , Conformação Proteica , Estabilidade Proteica , Saccharomyces cerevisiae/metabolismo , Proteínas Reguladoras de Informação Silenciosa de Saccharomyces cerevisiae/química , Proteínas Reguladoras de Informação Silenciosa de Saccharomyces cerevisiae/genética , Sirtuína 2/genética , Sirtuína 2/metabolismo
5.
EMBO J ; 38(8)2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30858281

RESUMO

SREBPs are master regulators of lipid homeostasis and undergo sterol-regulated export from ER to Golgi apparatus for processing and activation via COPII-coated vesicles. While COPII recognizes SREBP through its escort protein SCAP, factor(s) specifically promoting SREBP/SCAP loading to the COPII machinery remains unknown. Here, we show that the ER/lipid droplet-associated protein Cideb selectively promotes the loading of SREBP/SCAP into COPII vesicles. Sterol deprivation releases SCAP from Insig and enhances ER export of SREBP/SCAP by inducing SCAP-Cideb interaction, thereby modulating sterol sensitivity. Moreover, Cideb binds to the guanine nucleotide exchange factor Sec12 to enrich SCAP/SREBP at ER exit sites, where assembling of COPII complex initiates. Loss of Cideb inhibits the cargo loading of SREBP/SCAP, reduces SREBP activation, and alleviates diet-induced hepatic steatosis. Our data point to a linchpin role of Cideb in regulated ER export of SREBP and lipid homeostasis.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Proteínas Reguladoras de Apoptose/fisiologia , Retículo Endoplasmático/fisiologia , Complexo de Golgi/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Esteróis/farmacologia , Animais , Proteínas Reguladoras de Apoptose/genética , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/efeitos dos fármacos , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/fisiologia , Retículo Endoplasmático/efeitos dos fármacos , Complexo de Golgi/efeitos dos fármacos , Células HEK293 , Células Hep G2 , Homeostase , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Transporte Proteico , Proteína de Ligação a Elemento Regulador de Esterol 1/genética
6.
Bio Protoc ; 9(14): e3309, 2019 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-33654819

RESUMO

Lipid droplets (LDs) are central organelles in maintaining lipid homeostasis. Defective LD growth often results in the development of metabolic disorders. LD fusion and growth mediated by cell death-inducing DNA fragmentation factor alpha (DFFA)-like effector (CIDE) family proteins are crucial for various biological processes including unilocular LD formation in the adipocytes, lipid storage in the liver, milk lipid secretion in the mammary epithelia cells, and lipid secretion in the skin sebocytes. Previous methodology by Gong et al. (2011) first reported a lipid-exchange rate assay to evaluate the fusion ability of each LD pair in the cells mediated by CIDE family proteins and their regulators, but photobleaching issue remains a problem and a detailed procedure was not provided. Here, we provide an improved and detailed protocol for the lipid-exchange rate measurement. The three key steps for this assay are cell preparation, image acquisition, and data analysis. The images of the fluorescence recovery are acquired after photobleaching followed by the measurement of the intensity changes in the LD pair. The difference in fluorescent intensity is used to obtain the lipid exchange rate between the LDs. The accuracy and repetitiveness of the calculated exchange rates are assured with three-cycle of photobleaching process and the linear criteria in data fitting. With this quantitative assay, we are able to identify the functional roles of the key proteins and the effects of their mutants on LD fusion.

7.
J Biol Chem ; 293(50): 19330-19343, 2018 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-30361435

RESUMO

Lipid droplets (LDs) are intracellular organelles and a central site for lipid synthesis, storage, and mobilization. The size of LDs reflects the dynamic regulation of lipid metabolism in cells. Previously, we found that cell death-inducing DFFA-like effector C (CIDEC) mediates LD fusion and growth by lipid transfer through LD-LD contact sites in adipocytes and hepatocytes. The CIDE-N domains of CIDEC molecules form homodimers, whereas the CIDE-C domain plays an important role in LD targeting and enrichment. Here, using targeted protein deletions and GFP expression coupled with fluorescence microscopy, we identified a polybasic RKKR motif in the linker region that connects the CIDE-N and CIDE-C domains of CIDEC and functions as a regulatory motif for LD fusion. We found that deletion of the linker region or mutation of the RKKR motif increases the formation of supersized LDs compared with LD formation in cells with WT CIDEC. This enhanced LD fusion activity required the interaction between CIDE-N domains. Mechanistically, we found that the RKKR motif interacts with acidic phospholipids via electrostatic attraction. Loss of this motif disrupted the protein-lipid interaction, resulting in enhanced lipid droplet fusion activity and thus formation of larger LDs. In summary, we have uncovered a CIDEC domain that regulates LD fusion activity, a finding that provides insights into the inhibitory regulation of LD fusion through CIDEC-lipid interactions.


Assuntos
Gotículas Lipídicas/metabolismo , Fosfolipídeos/metabolismo , Proteínas/química , Proteínas/metabolismo , Células 3T3 , Motivos de Aminoácidos , Animais , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Camundongos , Fenótipo , Ligação Proteica
8.
Biochim Biophys Acta Mol Cell Biol Lipids ; 1862(10 Pt B): 1197-1204, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28648584

RESUMO

Cell death-inducing DFF45-like effector (CIDE) family proteins including Cidea, Cideb and Cidec/Fsp27 are expressed in many different tissues and are known as lipid droplet (LD)-and ER-associated proteins. Systematic analyses using genetically modified animal models have demonstrated that CIDE proteins play important roles in regulating various aspects of lipid homeostasis, including lipid storage, lipolysis and lipid secretion. Recent research in ours and other laboratories has revealed that CIDE proteins are crucial regulators of LD fusion and growth in the adipose tissue, liver, skin and mammary glands. CIDE-mediated LD fusion and growth is different from other membrane fusions in that it requires CIDE proteins to be enriched and clustered at the LD-LD contact sites (LDCS). The enriched CIDE proteins then allow the recruitment of other proteins to the LDCS and the formation of potential fusion pores. Neutral lipids in the smaller LDs of the contacted pair are transferred to the larger LDs, owing to the internal pressure difference, thus resulting in the fusion and growth of the LDs. This review summarizes the physiological roles of CIDE proteins in controlling lipid homeostasis, insulin sensitivity and the development of metabolic diseases including obesity, diabetes and fatty liver, with a particular focus on the role of CIDE proteins in controlling LD fusion and growth. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Gotículas Lipídicas/metabolismo , Metabolismo dos Lipídeos , Fusão de Membrana , Animais , Proteínas Reguladoras de Apoptose/genética , Diabetes Mellitus/genética , Diabetes Mellitus/metabolismo , Diabetes Mellitus/patologia , Fígado Gorduroso/genética , Fígado Gorduroso/metabolismo , Fígado Gorduroso/patologia , Humanos , Resistência à Insulina , Gotículas Lipídicas/patologia , Obesidade/genética , Obesidade/metabolismo , Obesidade/patologia
9.
J Clin Invest ; 127(4): 1353-1369, 2017 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-28287402

RESUMO

Obesity is characterized by aberrant fat accumulation. However, the intracellular signaling pathway that senses dietary fat and leads to fat storage remains elusive. Here, we have observed that the levels of histone deacetylase 6 (HDAC6) and the related family member HDAC10 are markedly reduced in adipose tissues of obese animals and humans. Mice with adipocyte-specific depletion of Hdac6 exhibited increased fat accumulation and reduced insulin sensitivity. In normal adipocytes, we found that reversal of P300/CBP-associated factor-induced (PCAF-induced) acetylation at K56 on cell death-inducing DFFA-like effector C (CIDEC, also known as FSP27) critically regulated lipid droplet fusion and lipid storage. Importantly, HDAC6 deacetylates CIDEC, leading to destabilization and reduced lipid droplet fusion. Accordingly, we observed elevated levels of CIDEC and its acetylated form in HDAC-deficient adipocytes as well as the adipose tissue of obese animals and humans. Fatty acids (FAs) prevented CIDEC deacetylation by promoting the dissociation of CIDEC from HDAC6, which resulted in increased association of CIDEC with PCAF on the endoplasmic reticulum. Control of CIDEC acetylation required the conversion of FAs to triacylglycerols. Thus, we have revealed a signaling axis that is involved in the coordination of nutrient availability, protein acetylation, and cellular lipid metabolic responses.


Assuntos
Histona Desacetilases/fisiologia , Metabolismo dos Lipídeos , Processamento de Proteína Pós-Traducional , Proteínas/metabolismo , Células 3T3-L1 , Acetilação , Tecido Adiposo Branco/metabolismo , Tecido Adiposo Branco/patologia , Animais , Retículo Endoplasmático/metabolismo , Ácidos Graxos/fisiologia , Células HEK293 , Desacetilase 6 de Histona , Humanos , Gotículas Lipídicas/metabolismo , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/enzimologia , Obesidade/patologia , Estabilidade Proteica , Triglicerídeos/biossíntese , Fatores de Transcrição de p300-CBP/metabolismo
10.
Mol Biol Cell ; 28(3): 381-386, 2017 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-27932495

RESUMO

Yeast silent heterochromatin provides an excellent model with which to study epigenetic inheritance. Previously we developed an in vitro assembly system to demonstrate the formation of filament structures with requirements that mirror yeast epigenetic gene silencing in vivo. However, the properties of these filaments were not investigated in detail. Here we show that the assembly system requires Sir2, Sir3, Sir4, nucleosomes, and O-acetyl-ADP-ribose. We also demonstrate that all Sir proteins and nucleosomes are components of these filaments to prove that they are SIR-nucleosome filaments. Furthermore, we show that the individual localization patterns of Sir proteins on the SIR-nucleosome filament reflect those patterns on telomeres in vivo. In addition, we reveal that magnesium exists in the SIR-nucleosome filament, with a role similar to that for chromatin condensation. These results suggest that a small number of proteins and molecules are sufficient to mediate the formation of a minimal yeast silent pre-heterochromatin in vitro.


Assuntos
Inativação Gênica/fisiologia , Nucleossomos/metabolismo , O-Acetil-ADP-Ribose/metabolismo , Sítios de Ligação , Cromatina/metabolismo , Montagem e Desmontagem da Cromatina , Epigenômica/métodos , Heterocromatina/metabolismo , Histonas/metabolismo , Magnésio , Processamento de Proteína Pós-Traducional , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas Reguladoras de Informação Silenciosa de Saccharomyces cerevisiae/genética , Proteínas Reguladoras de Informação Silenciosa de Saccharomyces cerevisiae/metabolismo , Sirtuínas/metabolismo , Telômero/metabolismo
11.
J Biol Chem ; 291(9): 4282-93, 2016 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-26733203

RESUMO

Lipid droplets (LDs) are dynamic subcellular organelles whose growth is closely linked to obesity and hepatic steatosis. Cell death-inducing DNA fragmentation factor-α-like effector (CIDE) proteins, including Cidea, Cideb, and Cidec (also called Fsp27), play important roles in lipid metabolism. Cidea and Cidec are LD-associated proteins that promote atypical LD fusion in adipocytes. Here, we find that CIDE proteins are all localized to LD-LD contact sites (LDCSs) and promote lipid transfer, LD fusion, and growth in hepatocytes. We have identified two types of hepatocytes, one with small LDs (small LD-containing hepatocytes, SLHs) and one with large LDs (large LD-containing hepatocytes, LLHs) in the liver. Cideb is localized to LDCSs and promotes lipid exchange and LD fusion in both SLHs and LLHs, whereas Cidea and Cidec are specifically localized to the LDCSs and promote lipid exchange and LD fusion in LLHs. Cideb-deficient SLHs have reduced LD sizes and lower lipid exchange activities. Fasting dramatically induces the expression of Cidea/Cidec and increases the percentage of LLHs in the liver. The majority of the hepatocytes from the liver of obese mice are Cidea/Cidec-positive LLHs. Knocking down Cidea or Cidec significantly reduced lipid storage in the livers of obese animals. Our data reveal that CIDE proteins play differential roles in promoting LD fusion and lipid storage; Cideb promotes lipid storage under normal diet conditions, whereas Cidea and Cidec are responsible for liver steatosis under fasting and obese conditions.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Fígado Gorduroso/etiologia , Hepatócitos/metabolismo , Gotículas Lipídicas/patologia , Obesidade/patologia , Proteínas/metabolismo , Animais , Proteínas Reguladoras de Apoptose/antagonistas & inibidores , Proteínas Reguladoras de Apoptose/genética , Linhagem Celular , Células Cultivadas , Privação de Alimentos , Hepatócitos/citologia , Hepatócitos/patologia , Hepatócitos/ultraestrutura , Humanos , Gotículas Lipídicas/ultraestrutura , Fusão de Membrana , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos Knockout , Camundongos Obesos , Obesidade/metabolismo , Obesidade/fisiopatologia , Biogênese de Organelas , Tamanho das Organelas , Perilipina-2 , Transporte Proteico , Proteínas/antagonistas & inibidores , Proteínas/genética , Interferência de RNA , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo
12.
Biochem Biophys Res Commun ; 439(3): 351-6, 2013 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-24012675

RESUMO

Receptor tyrosine kinases (RTKs) regulate many cellular processes, and Sprouty2 (Spry2) is known as an important regulator of RTK signaling pathways. Therefore, it is worth investigating the properties of Spry2 in more detail. In this study, we found that Spry2 is able to self-assemble into oligomers with a high-affinity KD value of approximately 16nM, as determined through BIAcore surface plasmon resonance analysis. The three-dimensional (3D) structure of Spry2 was resolved using an electron microscopy (EM) single-particle reconstruction approach, which revealed that Spry2 is donut-shaped with two lip-cover domains. Furthermore, the method of energy dispersive spectrum obtained through EM was analyzed to determine the elements carried by Spry2, and the results demonstrated that Spry2 is a silicon- and iron-containing protein. The silicon may contribute to the electroconductivity of Spry2, and this property exhibits a concentration-dependent feature. This study provides the first report of a silicon- and iron-containing protein, and its 3D structure may allow us (1) to study the potential mechanism through the signal transduction is controlled by switching the electronic transfer on or off and (2) to develop a new type of conductor or even semiconductor using biological or half-biological hybrid materials in the future.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/química , Proteínas de Membrana/química , Animais , Condutividade Elétrica , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Ferro/análise , Proteínas de Membrana/metabolismo , Microscopia Eletrônica , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Silício/análise
13.
Opt Lett ; 37(9): 1469-71, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22555707

RESUMO

We develop and test a thermally activated state transition technique for ultraweak force measurement. As a force sensor, the technique was demonstrated on a classical Brownian bead immersed in water and restrained by a bistable optical trap. A femto-Newton-level flow force imposed on this sensor was measured by monitoring changes in the transition rates of the bead hopping between two energy states. The treatment of thermal disturbances as a requirement instead of a limiting factor is the major feature of the technique, and provides a new strategy by which to measure other ultraweak forces beyond the thermal noise limit.

14.
Langmuir ; 28(19): 7428-35, 2012 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-22524463

RESUMO

The Klebsiella pneumoniae type 3 fimbriae are mainly composed of MrkA pilins that assemble into a helixlike filament. This study determined the biomechanical properties of the fimbriae and analyzed 11 site-directed MrkA mutants to identify domains that are critical for the properties. Escherichia coli strains expressing type 3 fimbriae with an Ala substitution at either F34, V45, C87, G189, T196, or Y197 resulted in a significant reduction in biofilm formation. The E. coli strain expressing MrkAG189A remained capable of producing a normal number of fimbriae. Although F34A, V45A, T196A, and Y197A substitutions expressed on E. coli strains produced sparse quantities of fimbriae, no fimbriae were observed on the cells expressing MrkAC87A. Further investigations of the mechanical properties of the MrkAG189A fimbriae with optical tweezers revealed that, unlike the wild-type fimbriae, the uncoiling force for MrkAG189A fimbriae was not constant. The MrkAG189A fimbriae also exhibited a lower enthalpy in the differential scanning calorimetry analysis. Together, these findings indicate that the mutant fimbriae are less stable than the wild-type. This study has demonstrated that the C-terminal ß strands of MrkA are required for the assembly and structural stability of fimbriae.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Fímbrias/metabolismo , Klebsiella pneumoniae/metabolismo , Proteínas de Bactérias/química , Biofilmes , Proteínas de Fímbrias/química , Estrutura Terciária de Proteína
15.
J Bacteriol ; 193(7): 1718-25, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21239584

RESUMO

This study investigated the structural and mechanical properties of Klebsiella pneumoniae type 3 fimbriae, which constitute a known virulence factor for the bacterium. Transmission electron microscopy and optical tweezers were used to understand the ability of the bacterium to survive flushes. An individual K. pneumoniae type 3 fimbria exhibited a helix-like structure with a pitch of 4.1 nm and a three-phase force-extension curve. The fimbria was first nonlinearly stretched with increasing force. Then, it started to uncoil and extended several micrometers at a fixed force of 66 ± 4 pN (n = 22). Finally, the extension of the fimbria shifted to the third phase, with a characteristic force of 102 ± 9 pN (n = 14) at the inflection point. Compared with the P fimbriae and type 1 fimbriae of uropathogenic Escherichia coli, K. pneumoniae type 3 fimbriae have a larger pitch in the helix-like structure and stronger uncoiling and characteristic forces.


Assuntos
Proteínas de Fímbrias/metabolismo , Fímbrias Bacterianas/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/metabolismo , Proteínas de Fímbrias/química , Proteínas de Fímbrias/genética , Fímbrias Bacterianas/química , Fímbrias Bacterianas/genética , Mecânica , Microscopia Eletrônica de Varredura , Conformação Proteica , Escherichia coli Uropatogênica/metabolismo , Fatores de Virulência
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...