A homolog of glyceraldehyde-3-phosphate dehydrogenase from Riemerella anatipestifer is an extracellular protein and exhibits biological activity

作     者：Ji-ye GAO Cui-lian YE Li-li ZHU Zhi-ying TIAN Zhi-bang YANG 

作者机构：Department of Basic Medicine Chongqing Medical University Chongqing 400016 China 

出 版 物：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 (浙江大学学报（英文版）B辑（生物医学与生物技术）)

年 卷 期：2014年第15卷第9期

页      面：776-787页

核心收录：

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 07[理学] 0906[农学-兽医学] 09[农学] 

基　　金：Project supported by the Fundamental Research Funds of the Central Universities of China(No.XDJK2013C009) 

主　　题：Riemerella anatipestifer Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) Extracellular protein 

摘      要：Riemerella anatipestifer is the causative agent of septicemia anserum exsudativa in ducks. Its pathogenesis and virulence factors are still unclear. The glycelytic enzyme, glyceraldehyde-3-phosphate dehydrogenase （GAPDH）, an anchorless and multifunctional protein on the surface of several pathogenic microorganisms, is involved in virulence and adhesion. Whether homologs of GAPDH exist, and display similar characteristics in R. anatipestifer （RaGAPDH） has not been determined. In our research, the RaGAPDH activity from various R. anatipestifer isolates was confirmed. Twenty-two gapdh genes from genornic DNA of R. anatipestifer isolates were cloned and sequenced for phylogenetic analysis. The distribution of RaGAPDH in R. anatipestifer CZ2 strain was confirmed by antisera to recombinant RaGAPDH. The ability of purified RaGAPDH to bind host proteins was analyzed by solid-phase ligandbinding assay. Results revealed that all R. anatipestifer isolates showed different levels of GAPDH activity except four strains, which contained a gapdh-like gene. The gapdh of R. anatipestifer, which is located phylogenetically in the same branch as enterohemorrhagic Escherichia coil （EHEC）, belonged to class I GAPDH, and encoded a 36.7-kDa protein. All RaGAPDH-encoding gene sequences from field isolates of R. anatipestiferdisplayed 100% homology. The RaGAPDH localized on the extracellular membrane of several R. anatipestifer strains. Further, it was released into the culture medium, and exhibited GAPDH enzyme activity. We also confirmed the binding of RaGAPDH to plasminogen and fibrinogen. These results demonstrated that GAPDH was present in R. anatipestifer, although not in all strains, and that RaGAPDH might contribute to the microorganism＇s virulence.