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Proteomics analysis based on iTRAQ LC-MS/MS reveals novel roles of hshB in Xanthomonas oryzae pv. oryzicola

Yancun Zhao: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences

<div><em>Xanthomonas</em> <em>oryzae</em> pv. <em>oryzicola</em> (<em>Xoc</em>) is the causal agent of the bacterial leaf streak (BLS) which is one of the most serious bacterial diseases in rice (<em>Oryza sativa</em>). Previous research showed that the transcription of the gene<em> hshB</em> was positively regulated by a diffusible signal factor (DSF)-dependent quorum sensing system, and it was required for the virulence, extracellular protease activity, extracellular polysaccharide production, and resistance to oxidative stress in <em>X</em>oc. To better understand functions of <em>hshB</em>, we conducted a comparative proteome analysis between <em>Xoc</em> wild type strain Rs105 and <em>hshB</em> mutant by using iTRAQ LC-MS/MS. The results clearly revealed that the expression of 621 proteins had significant changes in <em>hshB</em> mutant compared to the wild type strain. Among them, the expression of 150 proteins was significantly up-regulated, and 471 down-regulated. Based on our further analysis and experimental results, it showed that <em>hshB</em> could affect protein expression levels of 32 transcription factors, and 5 of them were demonstrated to be involved in the virulence, cell motility, extracellular polysaccharide production, and resistance to oxidative stress of <em>X</em>oc. Moreover, the direct interaction of HshB with <em>fleQ</em> promoter was demonstrated by gel shift assay. To our knowledge, our results revealed the regulation mechanism of <em>hshB</em> to transcription factors for the first time, and expanded understanding of <em>hshB </em>in <em>X</em>oc.</div>