scholarly journals Life in the Cold: a Proteomic Study of Cold-Repressed Proteins in the Antarctic Bacterium Pseudoalteromonas haloplanktis TAC125

2011 ◽  
Vol 77 (11) ◽  
pp. 3881-3883 ◽  
Author(s):  
Florence Piette ◽  
Salvino D'Amico ◽  
Gabriel Mazzucchelli ◽  
Antoine Danchin ◽  
Pierre Leprince ◽  
...  
Keyword(s):  
Heat Shock ◽  
Low Temperatures ◽  
Gel Electrophoresis ◽  
Two Dimensional ◽  
Content Type ◽  
Pseudoalteromonas Haloplanktis ◽  
Antarctic Bacterium ◽  
Proteomic Study ◽  
Shock Proteins ◽  
The Antarctic

ABSTRACTThe proteomes expressed at 4°C and 18°C by the psychrophilic Antarctic bacteriumPseudoalteromonas haloplanktiswere compared using two-dimensional differential in-gel electrophoresis with special reference to proteins repressed by low temperatures. Remarkably, the major cold-repressed proteins, almost undetectable at 4°C, were heat shock proteins involved in folding assistance.

scholarly journals Kinetic and structural optimization to catalysis at low temperatures in a psychrophilic cellulase from the Antarctic bacterium Pseudoalteromonas haloplanktis

2004 ◽  
Vol 384 (2) ◽  
pp. 247-253 ◽  
Author(s):  
Geneviève GARSOUX ◽  
Josette LAMOTTE ◽  
Charles GERDAY ◽  
Georges FELLER
Keyword(s):  
Active Site ◽  
Low Temperatures ◽  
Catalytic Domain ◽  
Homology Modelling ◽  
Temperature Adaptation ◽  
Substrate Affinity ◽  
Structural Factors ◽  
Pseudoalteromonas Haloplanktis ◽  
Antarctic Bacterium ◽  
The Antarctic

The cold-adapted cellulase CelG has been purified from the culture supernatant of the Antarctic bacterium Pseudoalteromonas haloplanktis and the gene coding for this enzyme has been cloned, sequenced and expressed in Escherichia coli. This cellulase is composed of three structurally and functionally distinct regions: an N-terminal catalytic domain belonging to glycosidase family 5 and a C-terminal cellulose-binding domain belonging to carbohydrate-binding module family 5. The linker of 107 residues connecting both domains is one of the longest found in cellulases, and optimizes substrate accessibility to the catalytic domain by drastically increasing the surface of cellulose available to a bound enzyme molecule. The psychrophilic enzyme is closely related to the cellulase Cel5 from Erwinia chrysanthemi. Both kcat and kcat/Km values at 4 °C for the psychrophilic cellulase are similar to the values for Cel5 at 30–35 °C, suggesting temperature adaptation of the kinetic parameters. The thermodynamic parameters of activation of CelG suggest a heat-labile, relatively disordered active site with low substrate affinity, in agreement with the experimental data. The structure of CelG has been constructed by homology modelling with a molecule of cellotetraose docked into the active site. No structural alteration related to cold-activity can be found in the catalytic cleft, whereas several structural factors in the overall structure can explain the weak thermal stability, suggesting that the loss of stability provides the required active-site mobility at low temperatures.

Heat-shock response of the entomopathogenic fungus Beauveria brongniartii

1996 ◽  
Vol 42 (6) ◽  
pp. 577-585 ◽  
Author(s):  
Ilungo J. Xavier ◽  
George G. Khachatourians
Keyword(s):  
Heat Shock ◽  
Entomopathogenic Fungi ◽  
Heat Shock Response ◽  
Gel Electrophoresis ◽  
2D Gel Electrophoresis ◽  
Two Dimensional ◽  
Beauveria Brongniartii ◽  
Shock Response ◽  
2D Gel ◽  
Shock Proteins

The heat-shock response of five strains of the entomopathogenic fungus Beauveria brongniartii was studied using two-dimensional (2D) gel electrophoresis. The fungal cells were heat shocked at 45 °C for 1 h and the total cellular protein was subjected to 2D gel electrophoresis. Proteins were separated in the first dimension using isoelectric focusing (pH range of 3.0–10) and in the second dimension by sodium dodecyl sulphate – polyacrylamide gel electrophoresis. More than 150 polypeptides for each strain were visualized by silver staining and have been assigned individual numbers as polypeptide coordinates. Analysis of the polypeptide map obtained by 2D gels indicated three patterns; several unique heat-shock proteins (HSPs) were (i) induced, (ii) enhanced, or (iii) repressed. Some of the HSPs induced by 45 °C were unique for each of the strains tested. Identification of heat-inducible protein synthesis or repression has ramifications for field survival and performance of entomopathogenic fungi. As well, the HSPs can be used as "signature proteins" for identification pruposes and this raises the possibility of using HSPs as a diagnostic tool applicable to other pest control fungi.Key words: heat-shock proteins, heat-shock response, two-dimensional electrophoresis, entomopathogenic fungi, Beauveria brongniartii.

scholarly journals Multiple Small Heat Shock Proteins in Rhizobia

1999 ◽  
Vol 181 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Martin Münchbach ◽  
Andreas Nocker ◽  
Franz Narberhaus
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Gel Electrophoresis ◽  
Immunoblot Analysis ◽  
Small Heat Shock Proteins ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis ◽  
Significant Similarity ◽  
Class A ◽  
Shock Proteins

ABSTRACT Seven genes coding for small heat shock proteins (sHsps) inBradyrhizobium japonicum have been identified. They are organized in five operons that are coordinately regulated by ROSE, a negatively cis-acting DNA element. The deduced sHsps can be divided into two separate classes: class A, consisting of proteins that show similarity to Escherichia coli IbpA and IbpB, and class B, whose members display significant similarity to other sHsps from prokaryotes and eukaryotes. Two-dimensional gel electrophoresis and Edman sequencing revealed the presence of at least 12 sHsps inB. japonicum, indicating a remarkable abundance of sHsps in this organism. Three additional members of class A and two potentially novel heat shock proteins were identified on the basis of their amino termini. The presence of multiple sHsps was also demonstrated for a variety of Rhizobium and Bradyrhizobium species by immunoblot analysis and two-dimensional gel electrophoresis. An extensive database survey revealed that, in contrast to the rhizobia, other bacteria contain maximally two sHsps whereas many plants have been reported to possess a sHsp superfamily.

scholarly journals Metagenomic Analysis of Stress Genes in Microbial Mat Communities from Antarctica and the High Arctic

2011 ◽  
Vol 78 (2) ◽  
pp. 549-559 ◽  
Author(s):  
Thibault Varin ◽  
Connie Lovejoy ◽  
Anne D. Jungblut ◽  
Warwick F. Vincent ◽  
Jacques Corbeil
Keyword(s):  
High Arctic ◽  
Environmental Stresses ◽  
The Arctic ◽  
Functional Responses ◽  
Protein Coding ◽  
Content Type ◽  
Stress Genes ◽  
Cyanobacterial Genes ◽  
Shock Proteins ◽  
The Antarctic

ABSTRACTPolar and alpine microbial communities experience a variety of environmental stresses, including perennial cold and freezing; however, knowledge of genomic responses to such conditions is still rudimentary. We analyzed the metagenomes of cyanobacterial mats from Arctic and Antarctic ice shelves, using high-throughput pyrosequencing to test the hypotheses that consortia from these extreme polar habitats were similar in terms of major phyla and subphyla and consequently in their potential responses to environmental stresses. Statistical comparisons of the protein-coding genes showed similarities between the mats from the two poles, with the majority of genes derived fromProteobacteriaandCyanobacteria; however, the relative proportions differed, with cyanobacterial genes more prevalent in the Antarctic mat metagenome. Other differences included a higher representation ofActinobacteriaandAlphaproteobacteriain the Arctic metagenomes, which may reflect the greater access to diasporas from both adjacent ice-free lands and the open ocean. Genes coding for functional responses to environmental stress (exopolysaccharides, cold shock proteins, and membrane modifications) were found in all of the metagenomes. However, in keeping with the greater exposure of the Arctic to long-range pollutants, sequences assigned to copper homeostasis genes were statistically (30%) more abundant in the Arctic samples. In contrast, more reads matching the sigma B genes were identified in the Antarctic mat, likely reflecting the more severe osmotic stress during freeze-up of the Antarctic ponds. This study underscores the presence of diverse mechanisms of adaptation to cold and other stresses in polar mats, consistent with the proportional representation of major bacterial groups.

Cold-adapted bacteria and the globin case study in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

2010 ◽  
Vol 3 (3-4) ◽  
pp. 125-131 ◽  
Author(s):  
Roberta Russo ◽  
Daniela Giordano ◽  
Alessia Riccio ◽  
Guido di Prisco ◽  
Cinzia Verde
Keyword(s):  
Cold Adapted ◽  
Pseudoalteromonas Haloplanktis ◽  
Antarctic Bacterium ◽  
Pseudoalteromonas Haloplanktis Tac125 ◽  
The Antarctic

scholarly journals Aspartate aminotransferase from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC 125

2000 ◽  
Vol 267 (9) ◽  
pp. 2790-2802 ◽  
Author(s):  
Leila Birolo ◽  
M. Luisa Tutino ◽  
Bianca Fontanella ◽  
Charles Gerday ◽  
Katia Mainolfi ◽  
...  
Keyword(s):  
Aspartate Aminotransferase ◽  
Pseudoalteromonas Haloplanktis ◽  
Antarctic Bacterium ◽  
The Antarctic
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