Zhu_2017_Microbiology_163_175

Spiroplasma eriocheiris is known to cause tremor disease in the Chinese mitten crab Eriocheir sinensis; however, the molecular characterization of this pathogen is still unclear. S. eriocheiris has the ability to invade and survive within mouse 3T6 cells. The invasion process may require causing damage to the host cell membrane by chemical, physical or enzymatic means. In this study, we systematically characterized a novel lysophospholipase (lysoPL) of S. eriocheiris TDA-040725-5T. The gene that encodes lysoPL in S. eriocheiris (SE-LysoPL) was cloned, sequenced and expressed in Escherichia coli BL21 (DE3). Enzymatic assays revealed that the purified recombinant SE-LysoPL hydrolysed long-chain acyl esterases at pH 7 and 30 degrees C. SE-LysoPL was detected in the membrane and cytoplasmic protein fractions using the SE-LysoPL antibody in Western blot. The virulence ability of S. eriocheiris was effectively reduced at the early stage of infection (m.o.i.=100) by the SE-LysoPL antibody neutralization test. To the best of our knowledge, this is the first study to identify and characterize a gene from S. eriocheiris encoding a protein exhibiting lysoPL and esterase activities. Our findings indicate that SE-LysoPL plays important roles in the pathogenicity of S. eriocheiris.