AUTHOR=Chen Rong , Yu Yanfei , Feng Zhixin , Gan Rong , Xie Xing , Zhang Zhenzhen , Xie Qingyun , Wang Weiwu , Ran Tingting , Zhang Wei , Xiong Qiyan , Shao Guoqing 

TITLE=Featured Species-Specific Loops Are Found in the Crystal Structure of Mhp Eno, a Cell Surface Adhesin From Mycoplasma hyopneumoniae

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=9

YEAR=2019

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2019.00209

DOI=10.3389/fcimb.2019.00209

ISSN=2235-2988

ABSTRACT=<p>Enolase is an evolutionarily conserved enzyme involved in the processes of glycolysis and gluconeogenesis. <italic>Mycoplasma hyopneumoniae</italic> belongs to <italic>Mycoplasma</italic>, whose species are wall-less and among the smallest self-replicating bacteria, and is an important colonizing respiratory pathogen in the pig industry worldwide. <italic>Mycoplasma hyopneumoniae</italic> enolase (<italic>Mhp</italic> Eno) expression is significantly increased after infection and was previously found to be a virulence factor candidate. Our studies show that <italic>Mhp</italic> Eno is a cell surface-localized protein that can adhere to swine tracheal epithelial cells (STECs). Adhesion to STECs can be specifically inhibited by an <italic>Mhp</italic> Eno antibody. <italic>Mhp</italic> Eno can recognize and interact with plasminogen with high affinity. Here, the first crystal structure of the mycoplasmal enolase from <italic>Mycoplasma hyopneumoniae</italic> was determined. The structure showed unique features of <italic>Mhp</italic> Eno in the S3/H1, H6/S6, H7/H8, and H13 regions. All of these regions were longer than those of other enolases and were exposed on the <italic>Mhp</italic> Eno surface, making them accessible to host molecules. These results show that <italic>Mhp</italic> Eno has specific structural characteristics and acts as a multifunctional adhesin on the <italic>Mycoplasma hyopneumoniae</italic> cell surface.</p>