Roles of export genes cgmA and lysE for the production of L-arginine and L-citrulline by Corynebacterium glutamicum
Roles of export genes cgmA and lysE for the production of L-arginine and L-citrulline by Corynebacterium glutamicum
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DOI：
10.1007/s00253-016-7695-1
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发表时间：
2016-10-01
影响因子：
5
通讯作者：
Wendisch, Volker F.
中科院分区：
文献类型：
--
作者：
Lubitz, Dorit;Jorge, Joao M. P.;Wendisch, Volker F.
L精氨酸是一种半必需氨基酸，广泛应用于化妆品、医药、食品等行业。代谢工程策略已被应用于谷氨酸棒杆菌过量生产L-精氨酸。Lyse是该细菌唯一已知的L-精氨酸输出物。然而，一株携带Lyse缺失的L精氨酸产生菌仍在生长培养基中积累了约10 mM的L精氨酸。过表达的腐胺和身体精氨酸输出渗透酶基因cgma被证明弥补了L-精氨酸输出中Lyse的缺乏。此外，通过质粒载体过表达CGMA可以缓解二肽Arg-Ala对谷氨酸双肽和Argo缺陷的谷氨酸杆菌和Argo缺陷的大肠杆菌菌株的毒性作用。抑制基因cgmR的缺失使L精氨酸滴度提高了5%。CGMA过表达不影响L-赖氨酸和L-瓜氨酸的合成。综上所述，CGMA不仅可以作为二胺腐胺和身体碱的出口系统，还可以作为L精氨酸的出口系统。L-赖氨酸和L-精氨酸赖氨酸的主要输出系统也可能在L-瓜氨酸的输出中起作用，因为当Lyse被删除时，L-瓜氨酸的产量减少，当Lyse产量过高时，L-瓜氨酸的产量提高了45%.
l-arginine is a semi-essential amino acid with application in cosmetic, pharmaceutical, and food industries. Metabolic engineering strategies have been applied for overproduction of l-arginine by Corynebacterium glutamicum. LysE was the only known l-arginine exporter of this bacterium. However, an l-arginine-producing strain carrying a deletion of lysE still accumulated about 10 mM l-arginine in the growth medium. Overexpression of the putative putrescine and cadaverine export permease gene cgmA was shown to compensate for the lack of lysE with regard to l-arginine export. Moreover, plasmid-borne overexpression of cgmA rescued the toxic effect caused by feeding of the dipeptide Arg-Ala to lysE-deficient C. glutamicum and argO-deficient Escherichia coli strains. Deletion of the repressor gene cgmR improved l-arginine titers by 5 %. Production of l-lysine and l-citrulline was not affected by cgmA overexpression. Taken together, CgmA may function as an export system not only for the diamine putrescine and cadaverine but also for l-arginine. The major export system for l-lysine and l-arginine LysE may also play a role in l-citrulline export since production of l-citrulline was reduced when lysE was deleted and improved by 45 % when lysE was overproduced.