阿拉伯海假交替单胞菌N1230-9两个甲基受体趋化蛋白的功能鉴定

Functions of two methyl-accepting chemotaxis proteins of Pseudoalteromonas arabiensis N1230-9

【目的】作为海洋中的特有及优势种群,假交替单胞菌(Pseudoalteromonas)普遍拥有多个甲基受体趋化蛋白(methyl-accepting chemotaxis protein,MCP),探究这些趋化受体的功能。【方法】以太平洋表层海水来源的一株阿拉伯海假交替单胞菌(Pseudoalteromonas arabiensis)N1230-9为研究对象,利用软琼脂平板法测试该菌株对23种碳源的趋化能力,继而利用同源重组策略构建2个含sCache结构域MCP编码基因(woc28264和woc27036)缺失突变体,并分析突变体对10种碳源的趋化能力。【结果】菌株N1230-9对海藻糖、麦芽糖、蔗糖、N-乙酰氨基葡萄糖、L-苹果酸、乙酸钠、丙酸钠、丙酮酸钠、柠檬酸和琥珀酸10种碳源具有趋化能力。WOC28264是L-苹果酸和蔗糖的特异性趋化受体,WOC27036则是柠檬酸和琥珀酸的特异性趋化受体。此外,WOC28264和WOC27036还均是N-乙酰氨基葡萄糖和海藻糖的趋化受体。【结论】WOC28264和WOC27036存在重叠的碳源效应物。

[Objective]Pseudoalteromonas,an endemic and dominant genus in the ocean,possesses multiple methyl-accepting chemotaxis proteins(MCPs),the functions of which remain unclear.[Methods]The chemotaxis of Pseudoalteromonas arabiensis N1230-9 isolated from surface seawater of the Pacific Ocean towards 23 carbon sources was analyzed by a plate-based assay for swimming motility.Two sCache domain-containing genes(woc28264 and woc27036)encoding MCPs were deleted by homologous recombination.The chemotaxis of the two mutants to 10 carbon sources was then analyzed.[Results]Strain N1230-9 showed obvious chemotaxis to 10 carbon sources:trehalose,maltose,sucrose,N-acetylglucosamine,L-malic acid,sodium acetate,sodium propionate,sodium pyruvate,citric acid,and succinic acid.WOC28264 was a specific chemotactic receptor for L-malic acid and sucrose,while WOC27036 was a specific chemotactic receptor for citric acid and succinic acid.Both WOC28264 and WOC27036 were chemotactic receptors for N-acetylglucosamine and trehalose.[Conclusion]WOC28264 and WOC27036 have overlapping carbon source effectors.