十字花科黑腐病菌编码RNA聚合酶ω亚基的基因（rpoZXcc）突变导致细胞生长减慢

ω（Omega）亚基是组成细菌RNA聚合酶（RNA polymerase,RNAP）核心酶的5个亚基（2α、β、β′andω）中最小的一个,也是5个亚基中唯一可以去除而不会导致细胞死亡的亚基。尽管ω亚基存在于所有细菌中并且序列非常保守,但迄今为止,人们对ω亚基的功能却知之甚少。基因组注释结果表明,十字花科黑腐病菌8004菌株（Xanthomonas campestris pv.campestris strain 8004,简称Xcc8004）基因组中存在一个编码ω亚基的基因rpoZXcc（ORF编号为XC0957）。为了研究Xcc RNA聚合酶ω亚基的功能,采用自杀质粒pK18mob整合突变方法,构建了rpoZXcc基因的非极性突变体NK0957。表型检测结果显示,NK0957在基本培养基MMX和丰富培养基NYG中的生长比野生型菌株Xcc8004的生长明显减慢,而且NK0957的生长缓慢表型能被rpoZXcc反式互补。这些结果说明,ω亚基在Xcc的生长过程中发挥重要作用。

Inactivation of rpoZXcc, a gene encodes the ω subunit of RNAP, results in reduced growth rate of Xanthomonas campestris pv. campestris

Omega（ω） is the smallest subunit of bacterial RNA polymerase（RNAP） core enzyme,which consists of five subunits（2α,β,β′,and ω）,and is the only subunit that is not essential for the RNAP enzyme activity and cell survival.Although ω subunit is widely distributed and highly conserved in various bacterial species,the exact role of ω in bacteria is largely unknown.Genome sequencing and annotation revealed that,the genome of Xanthomonas campestris pv.campestris strain 8004（Xcc8004） contains a gene,rpoZXcc（ORF number XC0957）,encoding the ω subunit of the Xcc RNAP.The present study has been performed to investigate the function of ω subunit of RNAP in Xcc,a non-polar mutant of rpoZXcc,NK0957,was constructed using plasmid pK18mob integration.Phenotype analysis showed that,the growth rate of NK0957 in the basal medium MMX and the rich medium NYG was significantly slower than that of the wild type strain Xcc8004.The slow-growth phenotype of NK0957 could be corrected by rpoZXcc in trans.These results implied that,the ω subunit plays an important role in the cell growth of Xcc.