Association of omega with the C-Terminal Region of the beta' Subunit Is Essential for Assembly of RNA Polymerase in Mycobacterium tuberculosis
Association of omega with the C-Terminal Region of the beta' Subunit Is Essential for Assembly of RNA Polymerase in Mycobacterium tuberculosis
复制标题
omega 与 β' 亚基 C 端区域的关联对于结核分枝杆菌中 RNA 聚合酶的组装至关重要
DOI：
10.1128/jb.00159-18
复制
发表时间：
2018
影响因子：
3.2
通讯作者：
Hu Yangbo
中科院分区：
文献类型：
--
作者：
Mao Chunyou;Zhu Yan;Lu Pei;Feng Lipeng;Chen Shiyun;Hu Yangbo
ω亚基是细菌RNA聚合酶（RNAP）的最小亚基。虽然ω的同源物在真核生物和古细菌中都是必需的，但已知该亚基在大肠杆菌和其他细菌中是RNAP的底物。在这项研究中，我们表征了ω亚基在结核分枝杆菌中不可或缺的作用。与研究得很好的E. coliRNAP、M.结核RNAP核心酶不能在ω亚基不存在的情况下进行功能组装。重要的是，M的取代。tuberculosis ω与E. coli或Thermus thermophilus不能恢复M.结核病RNAP。此外，通过替换M. tuberculosis ω与E. coli ω中发现了一个非保守的环区。结核病ω对于其在RNAP组装中的功能至关重要。从RNAP结构中，我们注意到β′亚基C端区域（β′CTD）在M.结核RNAP，而E. coli或T.嗜热菌RNAP靠近ω环区域。在M.结核RNAP使M. tuberculosis ω对RNAP和受损M.结核核心装配，这表明这两个区域可能共同发挥作用，发挥作用的ω-依赖RNAP组装在M。结核ω环和β′CTD区域的序列比对表明ω的基本作用可能仅限于分枝杆菌。总之，我们的研究表征了M.结核病的ω和强调的重要性，ω环区在M。DNA依赖性RNA聚合酶（RNAP）是细菌中唯一负责转录的酶，由一个多亚基核心酶（α2ββ′ω）和一个可分离的σ亚基组成。作为最小的亚基，ω的作用仍然是研究得最少的。在大肠杆菌和其他一些细菌中，已知ω亚基对于RNAP是非必需的。在这项研究中，我们揭示了在人类病原体结核分枝杆菌中RNAP组装的ω亚基的重要作用，并且还表征了在该功能中起作用的分枝杆菌特异性ω环。我们的研究为进一步表征细菌ω亚基的作用提供了新的见解。
The ω subunit is the smallest subunit of bacterial RNA polymerase (RNAP). Although homologs of ω are essential in both eukaryotes and archaea, this subunit has been known to be dispensable for RNAP in Escherichia coli and in other bacteria. In this study, we characterized an indispensable role of the ω subunit in Mycobacterium tuberculosis. Unlike the well-studied E. coli RNAP, the M. tuberculosis RNAP core enzyme cannot be functionally assembled in the absence of the ω subunit. Importantly, substitution of M. tuberculosis ω with ω subunits from E. coli or Thermus thermophilus cannot restore the assembly of M. tuberculosis RNAP. Furthermore, by replacing different regions in M. tuberculosis ω with the corresponding regions from E. coli ω, we found a nonconserved loop region in M. tuberculosis ω essential for its function in RNAP assembly. From RNAP structures, we noticed that the location of the C-terminal region of the β′ subunit (β′CTD) in M. tuberculosis RNAP but not in E. coli or T. thermophilus RNAP is close to the ω loop region. Deletion of this β′CTD in M. tuberculosis RNAP destabilized the binding of M. tuberculosis ω on RNAP and compromised M. tuberculosis core assembly, suggesting that these two regions may function together to play a role in ω-dependent RNAP assembly in M. tuberculosis. Sequence alignment of the ω loop and the β′CTD regions suggests that the essential role of ω is probably restricted to mycobacteria. Together, our study characterized an essential role of M. tuberculosis ω and highlighted the importance of the ω loop region in M. tuberculosis RNAP assembly.IMPORTANCEDNA-dependent RNA polymerase (RNAP), which consists of a multisubunit core enzyme (α2ββ′ω) and a dissociable σ subunit, is the only enzyme in charge of transcription in bacteria. As the smallest subunit, the roles of ω remain the least well studied. In Escherichia coli and some other bacteria, the ω subunit is known to be nonessential for RNAP. In this study, we revealed an essential role of the ω subunit for RNAP assembly in the human pathogen Mycobacterium tuberculosis, and a mycobacterium-specific ω loop that plays a role in this function was also characterized. Our study provides fresh insights for further characterizing the roles of bacterial ω subunit.