Cloning and expression of recombinant O-acetylserine lyase from human streptococcus suis serotype 2 in pichia pastoris

Abstract

Streptococcus suis is recognized worldwide as an important swine pathogen, which occasionally infects humans and causes fatal illnesses. O-acetylserine lyase (OASL) is responsible for the fi nal step of the cysteine biosynthesis, a key step in bacterial sulfur metabolism and offers a means by which inorganic sulfur maybe incorporated into cellular components. Recently, OASL was reported as a putative virulence-associated factor and immunogenic protein in S. suis. And this suggests that it may be involved in pathogenesis. In this study, the gene coding for OASL was cloned from a clinical S. suis serotype 2 strain. A full-length gene encoding OASL was amplifi ed by the OASL gene-specifi c primer. The amplifi ed fragments were cloned into pGAPZA vector and expression as a His-tagged recombinant protein in Pichia pastoris. The expressed sample collected from the supernatant was fi rst analyzed by SDS-PAGE. After that the recombinant proteins were detected by Ni2+-NTA enzyme conjugate. The Western immunoblotting showed that either antibodies present in patient serum suffered from S. suis infection or rabbit serum raised against whole cell lysate of homologous and heterologous strains can bind to recombinant OASL. These results verify that OASL had antigenicity and guide for evaluating its antigenic potential in further studies.