RESUMO
Iron is a key micronutrient essential for various essential biological processes. As a consequence, alteration in iron concentration in seawater can deeply influence marine biodiversity. In polar marine environments, where environmental conditions are characterized by low temperatures, the role of iron becomes particularly significant. While iron limitation can negatively influence primary production and nutrient cycling, excessive iron concentrations can lead to harmful algal blooms and oxygen depletion. Furthermore, the growth of certain phytoplankton species can be increased in high-iron-content environments, resulting in altered balance in the marine food web and reduced biodiversity. Although many chemical/physical methods are established for inorganic iron quantification, the determination of the bio-available iron in seawater samples is more suitably carried out using marine microorganisms as biosensors. Despite existing challenges, whole-cell biosensors offer other advantages, such as real-time detection, cost-effectiveness, and ease of manipulation, making them promising tools for monitoring environmental iron levels in polar marine ecosystems. In this review, we discuss fundamental biosensor designs and assemblies, arranging host features, transcription factors, reporter proteins, and detection methods. The progress in the genetic manipulation of iron-responsive regulatory and reporter modules is also addressed to the optimization of the biosensor performance, focusing on the improvement of sensitivity and specificity.
Assuntos
Biodiversidade , Técnicas Biossensoriais , Ferro , Água do Mar , Técnicas Biossensoriais/métodos , Ferro/metabolismo , Monitoramento Ambiental/métodos , Organismos Aquáticos , Fitoplâncton/metabolismo , Animais , EcossistemaRESUMO
Biofilm is accountable for nosocomial infections and chronic illness, making it a serious economic and public health problem. Staphylococcus epidermidis, thanks to its ability to form biofilm and colonize biomaterials, represents the most frequent causative agent involved in biofilm-associated infections of medical devices. Therefore, the research of new molecules able to interfere with S. epidermidis biofilm formation has a remarkable interest. In the present work, the attention was focused on Pseudomonas sp. TAE6080, an Antarctic marine bacterium able to produce and secrete an effective antibiofilm compound. The molecule responsible for this activity was purified by an activity-guided approach and identified by LC-MS/MS. Results indicated the active protein was a periplasmic protein similar to the Pseudomonas aeruginosa PAO1 azurin, named cold-azurin. The cold-azurin was recombinantly produced in E. coli and purified. The recombinant protein was able to impair S. epidermidis attachment to the polystyrene surface and effectively prevent biofilm formation.
Assuntos
Azurina , Pseudomonas , Azurina/metabolismo , Antibacterianos/metabolismo , Regiões Antárticas , Escherichia coli , Cromatografia Líquida , Espectrometria de Massas em Tandem , Biofilmes , Pseudomonas aeruginosa , Staphylococcus epidermidisRESUMO
Cyclin-dependent kinase-like 5 (CDKL5) is a serine/threonine protein kinase involved in human brain development and functioning. Mutations in CDKL5, especially in its catalytic domain, cause a severe developmental condition named CDKL5 deficiency disorder. Nevertheless, molecular studies investigating the structural consequences of such mutations are still missing. The CDKL5 catalytic domain harbors different sites of post-translational modification, such as phosphorylations, but their role in catalytic activity, protein folding, and stability has not been entirely investigated. With this work, we describe the expression pattern of the CDKL5 catalytic domain in Escherichia coli demonstrating that it predominantly aggregates. However, the use of solubility tags, the lowering of the expression temperature, the manual codon optimization to overcome an internal translational start, and the incubation of the protein with K+ and MgATP allow the collection of a soluble catalytically active kinase. Interestingly, the resulting protein exhibits hypophosphorylation compared to its eukaryotic counterpart, proving that bacteria are a useful tool to achieve almost unmodified CDKL5. Posing questions about the CDKL5 autoactivation mechanism and the determinants for its stability, this research provides a valuable platform for comparative biophysical studies between bacterial and eukaryotic-expressed proteins, contributing to our understanding of neurodevelopmental disorders associated with CDKL5 dysfunction.
Assuntos
Domínio Catalítico , Escherichia coli , Proteínas Serina-Treonina Quinases , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/química , Humanos , Escherichia coli/metabolismo , Escherichia coli/genética , Biossíntese de Proteínas , Agregados Proteicos , Síndromes Epilépticas/metabolismo , Síndromes Epilépticas/genética , Processamento de Proteína Pós-Traducional , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/genética , Espasmos InfantisRESUMO
The Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 (PhTAC125) is considered an interesting alternative host for the recombinant protein production, that can be explored when the conventional bacterial expression systems fail. Indeed, the manufacture of all the difficult-to-express proteins produced so far in this bacterial platform gave back soluble and active products. Despite these promising results, the low yield of recombinant protein production achieved is hampering the wider and industrial exploitation of this psychrophilic cell factory. All the expression plasmids developed so far in PhTAC125 are based on the origin of replication of the endogenous pMtBL plasmid and are maintained at a very low copy number. In this work, we set up an experimental strategy to select mutated OriR sequences endowed with the ability to establish recombinant plasmids at higher multiplicity per cell. The solution to this major production bottleneck was achieved by the construction of a library of psychrophilic vectors, each containing a randomly mutated version of pMtBL OriR, and its screening by fluorescence-activated cell sorting (FACS). The selected clones allowed the identification of mutated OriR sequences effective in enhancing the plasmid copy number of approximately two orders of magnitude, and the production of the recombinant green fluorescent protein was increased up to twenty times approximately. Moreover, the molecular characterization of the different mutant OriR sequences allowed us to suggest some preliminary clues on the pMtBL replication mechanism that deserve to be further investigated in the future. KEY POINTS: ⢠Setup of an electroporation procedure for Pseudoalteromonas haloplanktis TAC125. ⢠Two order of magnitude improvement of OriR-derived psychrophilic expression systems. ⢠Almost twenty times enhancement in Green fluorescent protein production.
Assuntos
Variações do Número de Cópias de DNA , Pseudoalteromonas , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas Recombinantes/metabolismo , Plasmídeos/genética , Pseudoalteromonas/genética , Pseudoalteromonas/metabolismoRESUMO
BACKGROUND: A significant fraction of the human proteome is still inaccessible to in vitro studies since the recombinant production of several proteins failed in conventional cell factories. Eukaryotic protein kinases are difficult-to-express in heterologous hosts due to folding issues both related to their catalytic and regulatory domains. Human CDKL5 belongs to this category. It is a serine/threonine protein kinase whose mutations are involved in CDKL5 Deficiency Disorder (CDD), a severe neurodevelopmental pathology still lacking a therapeutic intervention. The lack of successful CDKL5 manufacture hampered the exploitation of the otherwise highly promising enzyme replacement therapy. As almost two-thirds of the enzyme sequence is predicted to be intrinsically disordered, the recombinant product is either subjected to a massive proteolytic attack by host-encoded proteases or tends to form aggregates. Therefore, the use of an unconventional expression system can constitute a valid alternative to solve these issues. RESULTS: Using a multiparametric approach we managed to optimize the transcription of the CDKL5 gene and the synthesis of the recombinant protein in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 applying a bicistronic expression strategy, whose generalization for recombinant expression in the cold has been here confirmed with the use of a fluorescent reporter. The recombinant protein largely accumulated as a full-length product in the soluble cell lysate. We also demonstrated for the first time that full-length CDKL5 produced in Antarctic bacteria is catalytically active by using two independent assays, making feasible its recovery in native conditions from bacterial lysates as an active product, a result unmet in other bacteria so far. Finally, the setup of an in cellulo kinase assay allowed us to measure the impact of several CDD missense mutations on the kinase activity, providing new information towards a better understanding of CDD pathophysiology. CONCLUSIONS: Collectively, our data indicate that P. haloplanktis TAC125 can be a valuable platform for both the preparation of soluble active human CDKL5 and the study of structural-functional relationships in wild type and mutant CDKL5 forms. Furthermore, this paper further confirms the more general potentialities of exploitation of Antarctic bacteria to produce "intractable" proteins, especially those containing large intrinsically disordered regions.
Assuntos
Proteoma , Pseudoalteromonas , Regiões Antárticas , Temperatura Baixa , Síndromes Epilépticas , Humanos , Peptídeo Hidrolases/metabolismo , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteoma/metabolismo , Pseudoalteromonas/genética , Pseudoalteromonas/metabolismo , Proteínas Recombinantes , Serina , Espasmos Infantis , Treonina/metabolismoRESUMO
The development of new approaches to prevent microbial surface adhesion and biofilm formation is an emerging need following the growing understanding of the impact of biofilm-related infections on human health. Staphylococcus epidermidis, with its ability to form biofilm and colonize biomaterials, represents the most frequent causative agent involved in infections of medical devices. In the research of new anti-biofilm agents against S. epidermidis biofilm, Antarctic marine bacteria represent an untapped reservoir of biodiversity. In the present study, the attention was focused on Psychrobacter sp. TAE2020, an Antarctic marine bacterium that produces molecules able to impair the initial attachment of S. epidermidis strains to the polystyrene surface. The setup of suitable purification protocols allowed the identification by NMR spectroscopy and LC-MS/MS analysis of a protein-polysaccharide complex named CATASAN. This complex proved to be a very effective anti-biofilm agent. Indeed, it not only interferes with cell surface attachment, but also prevents biofilm formation and affects the mature biofilm matrix structure of S. epidermidis. Moreover, CATASAN is endowed with a good emulsification activity in a wide range of pH and temperature. Therefore, its use can be easily extended to different biotechnological applications.
Assuntos
Psychrobacter , Humanos , Antibacterianos/química , Cromatografia Líquida , Espectrometria de Massas em Tandem , Biofilmes , Staphylococcus epidermidisRESUMO
In this paper, the structure of the capsular polysaccharide isolated from the psychrotolerant bacterium Psychrobacter arcticus 273-4 is reported. The polymer was purified by gel filtration chromatography and the structure was elucidated by means of one- and two-dimensional NMR spectroscopy, in combination with chemical analyses. The polysaccharide consists of a trisaccharidic repeating unit containing two residues of glucose and a residue of a N,N-diacetyl-pseudaminic acid.
Assuntos
Psychrobacter , Parede Celular , Espectroscopia de Ressonância Magnética , PolissacarídeosRESUMO
Psychrobacter arcticus 273-4 is a Gram-negative bacterium isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in the Kolyma region in Siberia. The survival strategies adopted to live at subzero temperatures include all the outer membrane molecules. A strategic involvement in the well-known enhancement of cellular membrane fluidity is attributable to the lipopolysaccharides (LPSs). These molecules covering about the 75% of cellular surface contribute to cold adaptation through structural modifications in their portions. In this work, we elucidated the exact structure of lipid A moiety obtained from the lipopolysaccharide of P. arcticus grown at 4 °C, to mimic the response to the real environment temperatures. The lipid A was obtained from the LPS by mild acid hydrolysis. The lipid A and its partially deacylated derivatives were exhaustively characterized by chemical analysis and by means of ESI Q-Orbitrap mass spectrometry. Moreover, biological assays indicated that P. arcticus 273-4 lipid A may behave as a weak TLR4 agonist.
Assuntos
Temperatura Baixa , Lipídeo A/química , Psychrobacter/química , Aclimatação , Psychrobacter/metabolismoRESUMO
BACKGROUND: Recent biotechnological advancements have allowed for the adoption of Lactococcus lactis, a typical component of starter cultures used in food industry, as the host for the production of food-grade recombinant targets. Among several advantages, L. lactis has the important feature of growing on lactose, the main carbohydrate in milk and a majoritarian component of dairy wastes, such as cheese whey. RESULTS: We have used recombinant L. lactis NZ9000 carrying the nisin inducible pNZ8148 vector to produce MNEI, a small sweet protein derived from monellin, with potential for food industry applications as a high intensity sweetener. We have been able to sustain this production using a medium based on the cheese whey from the production of ricotta cheese, with minimal pre-treatment of the waste. As a proof of concept, we have also tested these conditions for the production of MMP-9, a protein that had been previously successfully obtained from L. lactis cultures in standard growth conditions. CONCLUSIONS: Other than presenting a new system for the recombinant production of MNEI, more compliant with its potential applications in food industry, our results introduce a strategy to valorize dairy effluents through the synthesis of high added value recombinant proteins. Interestingly, the possibility of using this whey-derived medium relied greatly on the choice of the appropriate codon usage for the target gene. In fact, when a gene optimized for L. lactis was used, the production of MNEI proceeded with good yields. On the other hand, when an E. coli optimized gene was employed, protein synthesis was greatly reduced, to the point of being completely abated in the cheese whey-based medium. The production of MMP-9 was comparable to what observed in the reference conditions.
Assuntos
Queijo/microbiologia , Lactococcus lactis/metabolismo , Proteínas/metabolismo , Soro do Leite/metabolismo , FermentaçãoRESUMO
Staphylococcus epidermidis, a harmless human skin colonizer, is a significant nosocomial pathogen in predisposed hosts because of its capability to form a biofilm on indwelling medical devices. In a recent paper, the purification and identification of the pentadecanal produced by the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125, able to impair S. epidermidis biofilm formation, were reported. Here the authors report on the chemical synthesis of pentadecanal derivatives, their anti-biofilm activity on S. epidermidis, and their action in combination with antibiotics. The results clearly indicate that the pentadecanal derivatives were able to prevent, to a different extent, biofilm formation and that pentadecanoic acid positively modulated the antimicrobial activity of the vancomycin. The cytotoxicity of these new anti-biofilm molecules was tested on two different immortalized eukaryotic cell lines in view of their potential applications.
Assuntos
Aldeídos/farmacologia , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Desinfetantes/farmacologia , Staphylococcus epidermidis/efeitos dos fármacos , Vancomicina/farmacologia , Aldeídos/síntese química , Aldeídos/química , Desinfetantes/síntese química , Desinfetantes/química , Sinergismo Farmacológico , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus epidermidis/crescimento & desenvolvimentoRESUMO
BACKGROUND: Pseudoalteromonas is a genus of ubiquitous marine bacteria used as model organisms to study the biological mechanisms involved in the adaptation to cold conditions. A remarkable feature shared by these bacteria is their ability to produce secondary metabolites with a strong antimicrobial and antitumor activity. Despite their biotechnological relevance, representatives of this genus are still lacking (with few exceptions) an extensive genomic characterization, including features involved in the evolution of secondary metabolites production. Indeed, biotechnological applications would greatly benefit from such analysis. RESULTS: Here, we analyzed the genomes of 38 strains belonging to different Pseudoalteromonas species and isolated from diverse ecological niches, including extreme ones (i.e. Antarctica). These sequences were used to reconstruct the largest Pseudoalteromonas pangenome computed so far, including also the two main groups of Pseudoalteromonas strains (pigmented and not pigmented strains). The downstream analyses were conducted to describe the genomic diversity, both at genus and group levels. This allowed highlighting a remarkable genomic heterogeneity, even for closely related strains. We drafted all the main evolutionary steps that led to the current structure and gene content of Pseudoalteromonas representatives. These, most likely, included an extensive genome reduction and a strong contribution of Horizontal Gene Transfer (HGT), which affected biotechnologically relevant gene sets and occurred in a strain-specific fashion. Furthermore, this study also identified the genomic determinants related to some of the most interesting features of the Pseudoalteromonas representatives, such as the production of secondary metabolites, the adaptation to cold temperatures and the resistance to abiotic compounds. CONCLUSIONS: This study poses the bases for a comprehensive understanding of the evolutionary trajectories followed in time by this peculiar bacterial genus and for a focused exploitation of their biotechnological potential.
Assuntos
Evolução Molecular , Genoma Bacteriano , Pseudoalteromonas/genética , Regiões Antárticas , Antibacterianos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Temperatura Baixa , Bases de Dados Genéticas , Transferência Genética Horizontal , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Filogenia , Pseudoalteromonas/classificação , Metabolismo Secundário/genéticaRESUMO
Colwellia psychrerythraea 34H is a Gram-negative cold-adapted microorganism that adopts many strategies to cope with the limitations associated with the low temperatures of its habitat. In this study, we report the complete characterization of the lipidâ A moiety from the lipopolysaccharide of Colwellia. Lipidâ A and its partially deacylated derivative were completely characterized by high-resolution mass spectrometry, NMR spectroscopy, and chemical analysis. An unusual structure with a 3-hydroxy unsaturated tetradecenoic acid as a component of the primary acylation pattern was identified. In addition, the presence of a partially acylated phosphoglycerol moiety on the secondary acylation site at the 3-position of the reducing 2-amino-2-deoxyglucopyranose unit caused tremendous natural heterogeneity in the structure of lipidâ A. Biological-activity assays indicated that C.â psychrerythraea 34H lipidâ A did not show an agonistic or antagonistic effect upon testing in human macrophages.
Assuntos
Alteromonadaceae/metabolismo , Lipídeo A/química , Temperatura Baixa , Cromatografia Gasosa-Espectrometria de Massas , Lipídeo A/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Staphylococcus epidermidis is a significant nosocomial pathogen in predisposed hosts because of its capability of forming a biofilm on indwelling medical devices. The initial stage of biofilm formation has a key role in S. epidermidis abiotic surface colonization. Recently, many strategies have been developed to create new anti-biofilm surfaces able to control bacterial adhesion mechanisms. In this work, the self-assembled amphiphilic layers formed by two fungal hydrophobins (Vmh2 and Pac3) have proven to be able to reduce the biofilm formed by different strains of S. epidermidis on polystyrene surfaces. The reduction in the biofilm thickness on the coated surfaces and the preservation of cell vitality have been demonstrated through confocal laser scanning microscope analysis. Moreover, the anti-biofilm efficiency of the self-assembled layers on different medically relevant materials has also been demonstrated using a CDC biofilm reactor.
Assuntos
Aderência Bacteriana/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Proteínas Fúngicas/química , Poliestirenos/química , Staphylococcus epidermidis/crescimento & desenvolvimento , Acremonium/química , Biofilmes/efeitos dos fármacos , Proteínas Fúngicas/isolamento & purificação , Proteínas Fúngicas/farmacologia , Interações Hidrofóbicas e Hidrofílicas , Viabilidade Microbiana/efeitos dos fármacos , Microscopia de Força Atômica , Microscopia Confocal , Pleurotus/química , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/fisiologia , Propriedades de SuperfícieRESUMO
Microbial biofilms are mainly studied due to detrimental effects on human health but they are also well established in industrial biotechnology for the production of chemicals. Moreover, biofilm can be considered as a source of novel drugs since the conditions prevailing within biofilm can allow the production of specific metabolites. Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 when grown in biofilm condition produces an anti-biofilm molecule able to inhibit the biofilm of the opportunistic pathogen Staphylococcus epidermidis. In this paper we set up a P. haloplanktis TAC125 biofilm cultivation methodology in automatic bioreactor. The biofilm cultivation was designated to obtain two goals: (1) the scale up of cell-free supernatant production in an amount necessary for the anti-biofilm molecule/s purification; (2) the recovery of P. haloplanktis TAC125 cells grown in biofilm for physiological studies. We set up a fluidized-bed reactor fermentation in which floating polystyrene supports were homogeneously mixed, exposing an optimal air-liquid interface to let bacterium biofilm formation. The proposed methodology allowed a large-scale production of anti-biofilm molecule and paved the way to study differences between P. haloplanktis TAC125 cells grown in biofilm and in planktonic conditions. In particular, the modifications occurring in the lipopolysaccharide of cells grown in biofilm were investigated.
Assuntos
Antibacterianos/biossíntese , Biofilmes/efeitos dos fármacos , Descoberta de Drogas/métodos , Pseudoalteromonas/metabolismo , Antibacterianos/farmacologia , Reatores Biológicos , Descoberta de Drogas/instrumentação , Fermentação , Pseudoalteromonas/crescimento & desenvolvimento , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/fisiologiaRESUMO
The Antarctic strain Pseudoalteromonas haloplanktisâ TAC125 is one of the model organisms of cold-adapted bacteria and is currently exploited as a new alternative expression host for numerous biotechnological applications. Here, we investigated several metabolic features of this strain through in silico modelling and functional integration of -omics data. A genome-scale metabolic model of P. haloplanktisâ TAC125 was reconstructed, encompassing information on 721 genes, 1133 metabolites and 1322 reactions. The predictive potential of this model was validated against a set of experimentally determined growth rates and a large dataset of growth phenotypic data. Furthermore, evidence synthesis from proteomics, phenomics, physiology and metabolic modelling data revealed possible drawbacks of cold-dependent changes in gene expression on the overall metabolic network of P. haloplanktisâ TAC125. These included, for example, variations in its central metabolism, amino acid degradation and fatty acid biosynthesis. The genome-scale metabolic model described here is the first one reconstructed so far for an Antarctic microbial strain. It allowed a system-level investigation of variations in cellular metabolic fluxes following a temperature downshift. It represents a valuable platform for further investigations on P. haloplanktisâ TAC125 cellular functional states and for the design of more focused strategies for its possible biotechnological exploitation.
Assuntos
Pseudoalteromonas/genética , Pseudoalteromonas/metabolismo , Regiões Antárticas , Temperatura Baixa , Perfilação da Expressão Gênica , Genoma Bacteriano/genética , Modelos Genéticos , Proteômica , TemperaturaRESUMO
BACKGROUND: Escherichia coli is, to date, the most used microorganism for the production of recombinant proteins and biotechnologically relevant metabolites. High density cell cultures allow efficient biomass and protein yields. However, their main limitation is the accumulation of acetate as a by-product of unbalanced carbon metabolism. Increased concentrations of acetate can inhibit cellular growth and recombinant protein production, and many efforts have been made to overcome this problem. On the other hand, it is known that E. coli is able to grow on acetate as the sole carbon source, although this mechanism has never been employed for the production of recombinant proteins. RESULTS: By optimization of the fermentation parameters, we have been able to develop a new acetate containing medium for the production of a recombinant protein in E. coli BL21(DE3). The medium is based on a buffering phosphate system supplemented with 0.5% yeast extract for essential nutrients and sodium acetate as additional carbon source, and it is compatible with lactose induction. We tested these culture conditions for the production of MNEI, a single chain derivative of the sweet plant protein monellin, with potential for food and beverage industries. We noticed that careful oxygenation and pH control were needed for efficient protein production. The expression method was also coupled to a faster and more efficient purification technique, which allowed us to obtain MNEI with a purity higher than 99%. CONCLUSIONS: The method introduced represents a new strategy for the production of MNEI in E. coli BL21(DE3) with a simple and convenient process, and offers a new perspective on the capabilities of this microorganism as a biotechnological tool. The conditions employed are potentially scalable to industrial processes and require only low-priced reagents, thus dramatically lowering production costs on both laboratory and industrial scale. The yield of recombinant MNEI in these conditions was the highest to date from E. coli cultures, reaching on average ~180 mg/L of culture, versus typical LB/IPTG yields of about 30 mg/L.
Assuntos
Acetatos/metabolismo , Escherichia coli/metabolismo , Proteínas de Plantas/biossíntese , Meios de Cultura/metabolismo , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Fermentação , Proteínas de Plantas/genéticaRESUMO
Psychrophilic microorganisms have successfully colonized all permanently cold environments from the deep sea to mountain and polar regions. The ability of an organism to survive and grow in cryoenviroments depends on a number of adaptive strategies aimed at maintaining vital cellular functions at subzero temperatures, which include the structural modifications of the membrane. To understand the role of the membrane in the adaptation, it is necessary to characterize the cell-wall components, such as the lipopolysaccharides, that represent the major constituent of the outer membrane. The aim of this study was to investigate the structure of the carbohydrate backbone of the lipooligosaccharide (LOS) isolated from the cold-adapted Psychrobacter arcticus 273-4. The strain, isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in Siberia, was cultivated at 4 °C. The LOS was isolated from dry cells and analyzed by means of chemical methods. In particular, it was degraded either by mild acid hydrolysis or by hydrazinolysis and investigated in detail by (1)H and (13)C NMR spectroscopy and by ESI FT-ICR mass spectrometry. The oligosaccharide was characterized by the substitution of the heptose residue, usually linked to Kdo in the inner core, with a glucose, and for the unusual presence of N-acetylmuramic acid.
Assuntos
Lipopolissacarídeos/química , Oligossacarídeos/química , Pergelissolo/microbiologia , Psychrobacter/química , Lipopolissacarídeos/isolamento & purificação , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Oligossacarídeos/isolamento & purificaçãoRESUMO
Microorganisms from Antarctica have evolved particular strategies to cope with cold. Moreover, they have been recently reported as producers of antimicrobial compounds, which inhibit the growth of other bacteria. In this work we characterized from different viewpoints the Gillisia sp. CAL575 strain, a psychrotrophic bacterium that produces microbial volatile organic compounds involved in the growth inhibition of Burkholderia cepacia complex members. Sequencing and analysis of the whole genome of Gillisia sp. CAL575 revealed that it includes genes that are involved in secondary metabolite production, adaptation to cold conditions, and different metabolic pathways for the production of energy. All these features make Gillisia sp. CAL575 a possible tool for biotechnology.
Assuntos
Antibacterianos/farmacologia , Flavobacteriaceae/genética , Genoma Bacteriano , Fenótipo , Compostos Orgânicos Voláteis/farmacologia , Adaptação Fisiológica , Complexo Burkholderia cepacia/efeitos dos fármacos , Temperatura Baixa , Flavobacteriaceae/química , Flavobacteriaceae/metabolismoRESUMO
Recombinant protein production in cold-adapted bacteria has proved to be a valuable option to overcome solubility concerns often came up in conventional expression hosts. ScFvs are examples of "difficult proteins" due to their tendency to form inclusion bodies when expressed in Escherichia coli. In this paper, the recombinant production of a single-chain antibody (ScFvOx) in the psychrophilic bacterium Pseudoalteromonas haloplanktis TAC125 is reported. The expression vector for the ScFvOx production was designed to address the recombinant protein in the periplasmic space and to allow the formation of the antibody disulphide bonds. For periplasmic export, two different export mechanisms were evaluated. By combining the genetic tools available for recombinant protein expression in psychrophilic hosts with an ad hoc medium and fermentation modality and optimised expression conditions at low temperatures, we obtained the highest yield of soluble and epitope-binding ScFvOx reported so far by conventional prokaryotic expression. The observed proficiency of the Antarctic bacterium to produce recombinant antibody fragments was related to the unusually high number of genes encoding peptidyl prolyl cis-trans isomerases found in P. haloplanktis TAC125 genome, making this bacterium the host of choice for the recombinant production of this protein class.
Assuntos
Pseudoalteromonas/metabolismo , Temperatura Baixa , Vetores Genéticos , Transporte Proteico , Pseudoalteromonas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Anticorpos de Cadeia Única/genética , Anticorpos de Cadeia Única/metabolismoRESUMO
Biofilms have great potential for producing valuable products, and recent research has been performed on biofilms for the production of compounds with biotechnological and industrial relevance. However, the production of recombinant proteins using this system is still limited. The recombinant protein production in microbial hosts is a well-established technology and a variety of expression systems are available. Nevertheless, the production of some recombinant proteins can result in proteolyzed, insoluble, and non-functional forms, therefore it is necessary to start the exploration of non-conventional production systems that, in the future, could be helpful to produce some "difficult" proteins. Non-conventional production systems can be based on the use of alternative hosts and/or on non-conventional ways to grow recombinant cells. In this paper, the use of the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 grown in biofilm conditions was explored to produce two fluorescent proteins, GFP and mScarlet. The best conditions for the production were identified by working on media composition, and induction conditions, and by building a new expression vector suitable for the biofilm conditions. Results reported demonstrated that the optimized system for the recombinant protein production in biofilm, although it takes longer than planktonic production, has the same potentiality as the classical planktonic approach with additional advantages since it needs a lower concentration of the carbon sources and doesn't require antibiotic addition. Moreover, in the case of mScarlet, the production in biofilm outperforms the planktonic system in terms of a better quality of the recombinant product.