ИСТИНА

Mollicutes or mycoplasmas are bacteria that lack a cell wall and have significant genome reduction. Mycoplasma gallisepticum is a cause agent of avian chronic respiratory disease. Mycoplasma infections can lead to acute inflammatory episodes, but most are chronic, suggesting that these bacteria have developed strategies to avoid host`s immune system response. In this work we focused on analysis of secreted (SP) and surfaceassociated proteins (SAP) of M.gallisepticum. For isolation of SP, washed bacterial culture in exponential phase was incubated for 2h in growth media without horse serum. For SAP, bacterial cells were treated with proteinase K. All samples were analyzed using LCMS. To exponentially access relative protein abundances, the modified protein abundance index was calculated. Two biological replicates were obtained. Proteins that were statistically significantly (pvalue < 0.05) enriched in secreted and surfaceassociated fractions compared with total proteome were accepted like positive results. There were 24 and 20 proteins, respectively. All SP have predicted signal peptide. SP were divided into four groups: IgGbinding proteins, serine proteases and two groups of proteins with uncharacterized function. Some genes are clustered in operons. There were three groups among SAP: variable lipoprotein family proteins, putative peptidases DUF31 and proteins with uncharacterized function. Identified proteins may be missed partners of known IgGbinding proteins putative peptidases DUF31 system. Three SP contain mitochondrial localization signal and one of them is predicted like mitotic checkpoint regulator. Some proteins were identified for the first time and these results can help to elucidate molecular mechanisms both of infection and escape host’s immune system response to mycoplasmas. This work was funded by the RSF grant 142400159 “Systems research of minimal cell on a Mycoplasma gallisepticum model”.