Nardmann J, Messer W
Max-Planck-Institut f. molekulare Genetik, Ihnestrasse 73, D-14195, Berlin, Germany.
Gene. 2000 Dec 31;261(2):299-303. doi: 10.1016/s0378-1119(00)00507-2.
The gene order in the dnaA region of Thermus thermophilus was determined. Previously, we showed that the putative oriC of T. thermophilus is located in the dnaA-dnaN intergenic region. In the 4 kb region upstream of the dnaA gene four ORFs were found, all orientated in the same direction which is opposite to that of dnaA. The ORFs were identified as T. thermophilus homologs of gidA, gidB, soj and spo0J of Bacillus subtilis. The gene order spo0J-soj-gidB-gidA-dnaA-dnaN resembles that of B. subtilis, Pseudomonas putida, Coxiella burnetii, Streptomyces coelicolor, Mycobacterium leprae, and Mycobacterium tuberculosis. We identified the transcriptional start point of the dnaA gene. The -10 region shows significant homology to the Escherichia coli -10 consensus sequence. The putative -35 region shows homology neither to the E. coli -35 consensus sequence nor to known -35 sequences of T. thermophilus. There are no DnaA boxes in the promoter region, and consequently dnaA transcription is not repressed by DnaA protein in vitro, i.e. the dnaA gene of T. thermophilus is not autoregulated.
确定了嗜热栖热菌dnaA区域的基因顺序。此前，我们表明嗜热栖热菌假定的oriC位于dnaA-dnaN基因间区域。在dnaA基因上游4 kb区域发现了4个开放阅读框（ORF），它们的方向均相同，与dnaA的方向相反。这些开放阅读框被鉴定为枯草芽孢杆菌gidA、gidB、soj和spo0J的嗜热栖热菌同源物。基因顺序spo0J-soj-gidB-gidA-dnaA-dnaN与枯草芽孢杆菌、恶臭假单胞菌、伯氏考克斯氏体、天蓝色链霉菌、麻风分枝杆菌和结核分枝杆菌的相似。我们确定了dnaA基因的转录起始点。-10区域与大肠杆菌-10共有序列具有显著同源性。假定的-35区域既不与大肠杆菌-35共有序列同源，也不与嗜热栖热菌已知的-35序列同源。启动子区域没有DnaA框，因此在体外dnaA转录不受DnaA蛋白抑制，即嗜热栖热菌的dnaA基因不是自我调节的。
