The structural and proteomic analysis of Spiroplasma eriocheiris in response to colchicine

Spiroplasma eriocheiris, a pathogen that causes mass mortality of Chinese mitten crab Eriocheir sinensis, is a wall less bacteria and belongs to the Mollicutes. This study was designed to investigate the effects of colchicine on S. eriocheiris growth, cell morphology, and proteins expression. We found that in the presence of colchicine, the spiroplasma cells lost their helicity, and the length of the cells in the experimental group was longer than that of the control. With varying concentrations of the colchicine treatment, the total time to achieve a stationary phase of the spiroplasma was increased, and the cell population was decreased. The virulence ability of S. eriocheiris to E. sinensis was effectively reduced in the presence of colchicine. To expound the toxical mechanism of colchicine on S. eriocheiris, 208 differentially expressed proteins of S. eriocheiris were reliably quantified by iTRAQ analysis, including 77 up-regulated proteins and 131 down-regulated proteins. Especially, FtsY, putative Spiralin, and NADH oxidase were down-regulated. F(0)F(1) ATP synthase subunit delta, ParB, DNABs, and NAD(FAD)-dependent dehydrogenase were up-regulated. A qRT-PCR was conducted to detect 7 expressed genes from the iTRAQ results during the incubation. The qRT-PCR results were consistent with the iTRAQ results. All of our results indicate that colchicine have a strong impact on the cell morphology and cellular metabolism of S. eriocheiris.