Stability of Cytochrome c₅ from Shewanella Species Isolated from Deep-Sea and Shallow-Water Areas

Abstract

Shewanella species are widely distributed in aquatic environments including deep-sea conditions. Proteins of deep-sea microorganisms are expected to adapt to the harsh environments, but their underlying mechanisms for the adaptation are still enigmatic because of multifactorial features of the deep-sea environments such as low temperature and high hydrostatic pressure. This review describes a case of the environmental adaptation of Shewanella cytochrome c₅ as a model protein in the aspect of protein stability. Cytochromes c₅ from the deep-sea Shewanella species exhibited higher stability than its homologues from shallow-water areas. Interestingly, the stability of deep-sea cytochromes c₅ is maintained even under the high-pressure conditions. High pressure is known to be a physical factor that affects the stability and functions of protein molecules, and the research using cytochromes c₅ suggests the potential for adaptation against pressure at the molecular levels.