Bioinformatics Analysis of Extracellular Keratinase KerQH2 from Rheinheimera sp.QH

Objective: To analyze and predict the structural characteristics and the site of interaction with the substrate of keratinase KerQH2 from marine bacteria Rheinheimera sp.QH, and to provide theoretical basis for further study on the degradation mechanism of keratin substrate by KerQH2. Methods: The bioinformatics technology was used to analyze the structural characteristics of keratinase KerQH2 and its possible sites and key amino acids on the keratin substrate. Results: KerQH2 was an S8 family serine protease, and the proportion of random coil on the molecular surface of KerQH2 was high; The proportion of α-helix and β-sheet was low, which were mainly located inside the enzyme molecule. KerQH2 contained a conserved catalytic triad in the order of Asp8, His41, Ser197. The surface electrostatic potential in the catalytic triad area was neutral. The KerQH2 catalytic domain contained a large number of conserved polar amino acids and aromatic amino acids, in addition to the sequences related to substrate binding were rich in Gly and Ala. KerQH2 mainly cut the peptide bond formed between hydrophobic amino acid Val(V)/ILe(I) and polar amino acid Cys(C)/Gln(Q). Conclusion: The special structure of KerQH2 helps to degrade complex keratins, which may be an adaptation of marine bacteria to marine oligotrophic environment.