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| 2. |
- Gómez-Consarnau, Laura, et al.
(författare)
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Proteorhodopsin phototrophy promotes survival of marine bacteria during starvation
- 2010
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Ingår i: PLoS biology. - : Public Library Science. - 1544-9173 .- 1545-7885. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Proteorhodopsins are globally abundant photoproteins found in bacteria in the photic zone of the ocean. Although their function as proton pumps with energy-yielding potential has been demonstrated, the ecological role of proteorhodopsins remains largely unexplored. Here, we report the presence and function of proteorhodopsin in a member of the widespread genus Vibrio, uncovered through whole-genome analysis. Phylogenetic analysis suggests that the Vibrio strain AND4 obtained proteorhodopsin through lateral gene transfer, which could have modified the ecology of this marine bacterium. We demonstrate an increased long-term survival of AND4 when starved in seawater exposed to light rather than held in darkness. Furthermore, mutational analysis provides the first direct evidence, to our knowledge, linking the proteorhodopsin gene and its biological function in marine bacteria. Thus, proteorhodopsin phototrophy confers a fitness advantage to marine bacteria, representing a novel mechanism for bacterioplankton to endure frequent periods of resource deprivation at the ocean’s surface.
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| 4. |
- Ishikawa, Takahiko, et al.
(författare)
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Pathoadaptive conditional regulation of the type VI secretion system in Vibrio cholerae O1 strains
- 2012
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Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 80:2, s. 575-584
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Tidskriftsartikel (refereegranskat)abstract
- The most recently discovered secretion pathway in gram-negative bacteria, the type VI secretion system (T6SS), is present in many species and is considered important for the survival of non-O1 non-O139 Vibrio cholerae in aquatic environments. Until now, it was not known whether there is a functionally active T6SS in wild-type V. cholerae O1 strains, the cause of cholera disease in humans. Here, we demonstrate the presence of a functionally active T6SS in wild-type V. cholerae O1 strains, as evidenced by the secretion of the T6SS substrate Hcp, which required several gene products encoded within the putative vas gene cluster. Our analyses showed that the T6SS of wild-type V. cholerae O1 strain A1552 was functionally activated when the bacteria were grown under high-osmolarity conditions. The T6SS was also active when the bacteria were grown under low temperature (23°C), suggesting that the system may be important for the survival of the bacterium in the environment. A test of the interbacterial virulence of V. cholerae strain A1552 against an Escherichia coli K-12 strain showed that it was strongly enhanced under high osmolarity and that it depended on the hcp genes. Interestingly, we found that the newly recognized osmoregulatory protein OscR plays a role in the regulation of T6SS gene expression and secretion of Hcp from V. cholerae O1 strains.
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- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 8. |
- Milton, Debra L., et al.
(författare)
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Cloning of a metalloprotease gene involved in the virulence mechanism of Vibrio anguillarum
- 1992
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Ingår i: Journal of Bacteriology. - 0021-9193 .- 1098-5530. ; 174:22, s. 7235-7244
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Tidskriftsartikel (refereegranskat)abstract
- Genetic evidence has previously suggested that a zinc metalloprotease is involved in the invasive mechanism of the fish pathogen Vibrio anguillarum NB10. In this study, the metalloprotease gene was cloned and sequenced. The sequence encodes a polypeptide (611 amino acids) that contains a putative signal sequence followed by a large leader sequence and the mature protein (44.6 kDa). Since the purified protein has a molecular mass of 36 kDa instead of the predicted 44.6 kDa, the mature protein is most likely processed a third time. Comparative analyses of the protein sequence showed high homologies to other bacterial metalloproteases within the zinc-binding and active-site regions. The Vibrio cholerae hemagglutinin/protease and the Pseudomonas aeruginosa elastase were exceptions in that the homology extended throughout the entire putative preproprotein. A chromosomal metalloprotease mutant was made via the integration of foreign DNA into the protease gene. This mutant did not secrete the metalloprotease, as determined by sodium dodecyl sulfate (SDS)-polyacrylamide protein analysis and by growth on gelatin agar. Transcomplementation of the chromosomal mutation revived the secretion of the metalloprotease and its activity on gelatin agar. Interestingly, when supernatant proteins were analyzed by gelatin-SDS-polyacrylamide electrophoresis, two different proteases (75 and 30 kDa) were detected in the mutant strain but not in the transcomplemented strain or the wild-type strain. Moreover, fish infection studies were done, and implications for the role of the metalloprotease in the virulence mechanism of V. anguillarum are discussed.
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| 9. |
- Milton, Debra L., et al.
(författare)
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Sequence of a novel virulence-mediating gene, virC, from Vibrio anguillarum
- 1995
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Ingår i: Gene. - 0378-1119 .- 1879-0038. ; 164:1, s. 95-100
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Tidskriftsartikel (refereegranskat)abstract
- Previously, the double-transposon (Tn) mutant VAN20 of Vibrio anguillarum (Va) 775.17B was isolated. This mutant lacked a major surface antigen (MSA) suggested to be a lipopolysaccharide (LPS) and showed a 10(5)-fold increase in the 50% lethal dose (LD50) when fish were infected intraperitoneally. In this study, the two Tn insertion sites within the chromosome were identified, a plasmid insertion mutation was made at each locus in a more virulent strain of Va, NB10, and the virulence was analyzed. One mutant displayed a 10(4)-fold increase in LD50, whereas the second mutant showed the wild-type (wt) phenotype. However, both mutants still expressed the MSA, suggesting that there may be more than two Tn insertions in VAN20 or that a double mutation is required to prevent production of the MSA. The DNA locus for the virulent phenotype was cloned and sequenced. A potential transcriptional unit consisting of three putative open reading frames (ORFs) was identified. The Tn was located in the second ORF, virC (virulence). The first ORF (34.8 kDa) showed 30% homology to the Escherichia coli and Salmonella typhimurium cysG (cysteine) genes. The virC gene (51.4 kDa) and the third ORF (24 kDa) showed no homology to other proteins in GenBank. Plasmid insertion mutants were made within each of these ORFs and the virulence was assayed. Only the virC mutant showed a loss in virulence, indicating that virC is a novel gene that is essential for the virulence of Va.
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