Hyperstable Proteins in the Gut Microbiota: An Examination of the Bacterium Bacteroides fragilis

Abstract

Unlike the vast majority of proteins, hyperstable or kinetically stable proteins (KSPs) are unaffected by a wide range of proteases, detergents, and other denaturants. The electrophoretic method diagonal two-dimensional (D2D) SDS-PAGE exploits the SDS-resistance of KSPs to isolate them from complex mixtures. D2D SDS-PAGE coupled with MALDI-TOF MS peptide mass fingerprinting allows KSPs to be isolated and identified from a wide range of biological lysates. Subsequently, through structural and functional analysis, trends in protein hyperstability may be postulated. The present study explores the role of endogenous KSPs in the Gram-negative, nanoaerobic bacterium Bacteroides fragilis, one of the most commonly found organisms in the human colon microbiota. In particular, the KSPs found in B. fragilis suggest that the organism prioritizes, and is constantly prepared for, management of oxygen related stresses. Continued identification of the presence and roles of hyperstable proteins, not only in B. fragilis but other organisms as well, may provide insight into the biological necessity and structure of proteins with elevated kinetic stability. Such findings may be utilized in science and engineering with medical and biotechnological implications.