Correlation between the optimal growth pressures of four Shewanella species and the stabilities of their cytochromes c 5.
Shewanella species live widely in deep-sea and shallow-water areas, and thus grow piezophilically and piezosensitively. Piezophilic and psychrophilic Shewanella benthica cytochrome c 5 (SB cytc 5) was the most stable against guanidine hydrochloride (GdnHCl) and thermal denaturation, followed by less piezophilic but still psychrophilic Shewanella violacea cytochrome c 5 (SV cytc 5). These two were followed, as to stability level, by piezosensitive and mesophilic Shewanella amazonensis cytochrome c 5 (SA cytc 5), and piezosensitive and psychrophilic Shewanella livingstonensis cytochrome c 5 (SL cytc 5). The midpoint GdnHCl concentrations of SB cytc 5, SV cytc 5, SL cytc 5, and SA cytc 5 correlated with the optimal growth pressures of the species, the correlation coefficient value being 0.93. A similar trend was observed for thermal denaturation. Therefore, the stability of each cytochrome c 5 is related directly to its host's optimal growth pressure. Phylogenetic analysis indicated that Lys-37, Ala-41, and Leu-50 conserved in piezosensitive SL cytc 5 and SA cytc 5 are ancestors of the corresponding residues in piezophilic SB cytc 5 and SV cytc 5, Gln, Thr, and Lys, respectively, which might have been introduced during evolution on adaption to environmental pressure. The monomeric Shewanella cytochromes c 5 are suitable tools for examining protein stability with regard to the optimal growth pressures of the source species.
Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
Misa
M
Masanari
Satoshi
S
Wakai
Manabu
M
Ishida
Chiaki
C
Kato
Yoshihiro
Y
Sambongi
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045304:Cytochromes c / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006874:Hydrostatic Pressure; D008969:Molecular Sequence Data; D010802:Phylogeny; D020592:Shewanella / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D013045:Species Specificity
D001426:Bacterial Proteins; D045304:Cytochromes c