title: Isolation and characterization of the gene encoding single-stranded-DNA-binding protein (SSB) from four marine Shewanella strains that differ in their temperature and pressure optima for growth.
abstract: The ssb gene, coding for single-stranded-DNA-binding protein (SSB), was cloned from four marine Shewanella strains that differed in their temperature and pressure optima and ranges of growth. All four Shewanella ssb genes complemented Escherichia coli ssb point and deletion mutants, with efficiencies that varied with temperature and ssb gene source. The Shewanella SSBs are the largest bacterial SSBs identified to date (24.9-26.3 kDa) and may be divided into conserved amino- and carboy-terminal regions and a highly variable central region. Greater amino acid sequence homology was observed between the Shewanella SSBs as a group (72-87%) than with other bacterial SSBs (52-69%). Analysis of the amino acid composition of the Shewanella SSBs revealed several features that could correlate with pressure or temperature adaptation. SSBs from the three low-temperature-adapted Shewanella strains were an order of magnitude more hydrophilic than that from the mesophilic strain, and differences in the distribution of eight amino acids were identified which could contribute to either the temperature or pressure adaptation of the proteins. The SSBs from all four Shewanella strains were overproduced and partially purified based upon their ability to bind single-stranded DNA. The differences found among the Shewanella SSBs suggest that these proteins will provide a useful system for exploring the adaptation of protein-protein and protein-DNA interactions at low temperature and high pressure.
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202, USA.
authors.forename: Lakshmi N
authors.initials: LN
authors.lastname: Chilukuri
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202, USA.
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Bartlett
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D003001:Cloning, Molecular; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006092:Gram-Negative Facultatively Anaerobic Rods / Q000235:genetics*; D006874:Hydrostatic Pressure; D008386:Marine Biology; D008969:Molecular Sequence Data; D017354:Point Mutation; D011994:Recombinant Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013696:Temperature; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins