Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India. santosh78 @rediffmail.com
Microbiol Res. 2011 Sep 20;166(6):508-14. doi: 10.1016/j.micres.2010.10.005. Epub 2011 Jan 15.
Details of the mechanism of DNA replication in the slow growing pathogen Mycobacterium tuberculosis (M. tb) are unknown. The dnaA and dnaN gene products are essential for chromosome replication and growth of a bacterium. Here we analyzed the transcriptional activity at the oriC locus in M. tb that includes dnaA, dnaN and recF. dnaA and dnaN are each transcribed from a transcription start point (TSP) located at -261 bp and -113 bp, respectively. recF is co-transcribed with dnaN and both genes are co-induced in stationary phase cultures of M. tb. Transcription was also observed inside the oriC region and leftward transcription predominated over rightward transcription. The transcriptional activity of dnaA, dnaN and recF genes was found to be unchanged under all the stress conditions that were examined except during hypoxia when a ∼2-fold decrease in dnaA and dnaN transcription was observed. This analysis of transcription at the oriC locus would be useful for future studies to assess the link if any between transcription at this locus and DNA replication.
分枝杆菌（M. tb）生长缓慢，其 DNA 复制的机制细节尚不清楚。dnaA 和 dnaN 基因产物对染色体复制和细菌生长是必不可少的。在这里，我们分析了分枝杆菌 oriC 基因座的转录活性，其中包括 dnaA、dnaN 和 recF。dnaA 和 dnaN 分别从位于-261 bp 和-113 bp 的转录起始点（TSP）转录。recF 与 dnaN 共转录，在分枝杆菌的静止期培养物中，这两个基因共同诱导。oriC 区域内也观察到转录，并且左向转录优先于右向转录。除了在缺氧条件下观察到 dnaA 和 dnaN 转录下降约 2 倍外，在所检查的所有应激条件下，dnaA、dnaN 和 recF 基因的转录活性均未发生变化。对 oriC 基因座转录的这种分析将有助于未来的研究评估该基因座的转录与 DNA 复制之间的联系（如果存在的话）。
