溶氧影响土壤杆菌ATCC 31749发酵生产热凝胶的蛋白质组学

Proteomic analysis of curdlan-producing Agrobacterium sp． ATCC 31749 in response to dissolved oxygen

摘要:

摘要:【目的】土壤杆菌(Agrobacterium sp.)ATCC 31749在氮源限制条件下生物合成热凝胶是一个专性好氧过程，在微氧和缺氧条件下，热凝胶的合成受到严重限制。为探寻溶氧影响微生物多糖合成的代谢途径和调控机制，本研究比较了不同溶氧条件下(75%，50%，25%，5%)土壤杆菌发酵生产热凝胶的蛋白质组差异。【方法】利用蛋白质二维电泳技术，分离出不同溶氧水平下土壤杆菌显著表达差异的胞内蛋白，利用质谱MALDI-TOF/TOF鉴定二维电泳表达差异蛋白点，并分析热凝胶合成过程中溶氧对相关蛋白表达的影响。【结果】在4个溶氧水平下成功鉴定出15个显著差异蛋白，主要参与多糖合成、脂肪酸合成、氨基酸合成等途径。其中葡萄糖磷酸变位酶和乳清苷5-磷酸脱羧酶直接参与调控热凝胶合成。【结论】溶氧可显著影响与热凝胶合成途径相关蛋白的表达，高溶氧水平可增加热凝胶前体物质UDP-葡萄糖的积累，使更多的UDP-葡萄糖用来合成热凝胶。

Abstract:

Abstract:［Objective］Curdlan is produced by Agrobacterium sp．ATCC 31749 under nitrogen limiting condition．The biosynthesis of crudlan is a typical aerobic bioprocess，and the production of curdlan would be severely restricted under micro-aerobic and anoxic conditions．Proteomic analysis of Agrobacterium sp． was conducted to investigate the effect of dissolved oxygen on the crucial enzymes involved in curdlan biosynthesis.［Methods］Two-dimensional gel electrophoresis was performed to separate and visualize the differential expression of the intracellular proteins extracted from Agrobacterium sp．ATCC 31749 cultured under various dissolved oxygen levels (75%，50%，25% and 5%). In addition，a comparative proteomic analysis of the intracellular proteins expression level under various dissolved oxygen levels was done． Significant differently expressed proteins were identified by MALDI-TOF/TOF.［Results］Finally，we identified 15 differently expressed proteins involved in polysaccharide synthesis，fatty acid synthesis，amino acid synthesis pathway．Among these proteins，phosphoglucomutase and orotidine 5-phosphate decarboxylase were the key metabolic enzymes directing curdlan biosynthesis.［Conclusion］Oxygen could affect the expression of the proteins taking charge of curdlan synthesis significantly.