短乳杆菌2-34中瓜氨酸转运蛋白的鉴定

Identification of a putative citrulline transporter in Lactobacillus brevis 2-34

摘要:

【背景】从黄酒发酵液中分离的短乳杆菌2-34具有重吸收瓜氨酸的能力，可用于降低黄酒中的瓜氨酸从而减少氨基甲酸乙酯的形成，然而瓜氨酸重吸收机制的不明确阻碍了该菌的合理利用。【目的】通过确定短乳杆菌2-34中的瓜氨酸转运蛋白编码基因，为其在黄酒中的利用提供理论依 据。【方法】以pRSFDuet-1和pETDuet-1为表达载体，通过多顺反子串联表达系统及双质粒表达系统，在大肠杆菌C43(DE3)中表达短乳杆菌2-34精氨酸脱亚胺途径中瓜氨酸代谢相关蛋白：精氨酸降解酶ArcD和ADI、瓜氨酸降解酶OTC及膜蛋白DcuC和AO antiporter。【结果】重组表达大肠杆菌发酵过程中可利用精氨酸形成瓜氨酸，但表达了膜蛋白DcuC和AO antiporter的重组菌发酵液中瓜氨酸含量较低。【结论】短乳杆菌2-34中DcuC和AO antiporter均具有吸收瓜氨酸的功能，且DcuC活性更高。

Abstract:

[Background] Citrulline and ethyl carbamate are hazards generated during rice wine fermentation. From rice wine fermentation broth Lactobacillus brevis 2-34 is isolated with the potential to reabsorb citrulline. [Objective] To identify genes encoding citrulline transporters in this strain will help its effective application in rice wine fermentation. [Methods] With vectors pRSFDuet-1 and pETDuet-1, citrulline metabolism-related enzymes of L. brevis 2-34, including arginine/ornithine antiporter, arginine deaminase, ornithine carbamyltransferase, as well as the two putative citrulline transporters, C4-dicarboxylate anaerobic carrier and AO antiporter, were expressed in Escherichia coli C43(DE3). [Results] Recombinant E. coli had similar citrulline reabsorption ability as L. brevis 2-34. Both putative transporters could absorb extracellular citrulline, and the transporting capability of DcuC was much stronger. [Conclusion] DcuC and AO antiporter are citrulline transporters in L. brevis 2-34.