Francis F, Ramirez-Arcos S, Salimnia H, Victor C, Dillon J R
Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada.
Gene. 2000 Jun 27;251(2):141-51. doi: 10.1016/s0378-1119(00)00200-6.
A cluster of genes involved in cell division and cell wall (dcw) biosynthesis was identified in Neisseria gonorrhoeae using genomic analysis and through verification of gene order by polymerase chain reaction (PCR) analysis. The gonococcal dcw cluster consists of 17 genes, in the order 5'-mraZ-mraW-ftsI-murE-hyp1-murF- mraY-hyp2-murD-ftsW-murG-murC-ddl -ft sQ-ftsA-ftsZ-hyp3-3'. The gene organization of the dcw cluster of N. gonorrhoeae is more similar to that observed in Gram-negative rods such as Escherichia coli and Haemophilus influenzae than in Gram-positive bacteria. The cluster is characterized by several intergenic spaces. Compared with E. coli, two genes, ftsL and envA, are absent in the gonococcal dcw cluster and three hypothetical genes are novel to the cluster. The cluster is flanked by two transcriptional terminators consisting of paired neisserial uptake sequences and also includes four internal terminators, three of which are paired neisserial uptake sequences. We also found that a repeated sequence on the gonococcal genome, commonly called a Correia element, acts as the fourth transcriptional terminator. All termination sequences were shown to be fully functional by using reverse transcription PCR experiments. Transcriptional start sites upstream of ftsQ, ftsA and ftsZ were determined by primer extension and six promoters were identified; three promoters were located upstream of ftsZ in the intergenic space, two were upstream of ftsA within ftsQ and one was upstream of ftsQ within ddl. Some of these promoters were preferentially used under anaerobic conditions. The location of these promoters differed from those described in E. coli indicating dissimilar transcriptional regulation.
利用基因组分析，并通过聚合酶链反应（PCR）分析验证基因顺序，在淋病奈瑟菌中鉴定出了一组参与细胞分裂和细胞壁（dcw）生物合成的基因。淋病奈瑟菌的dcw基因簇由17个基因组成，顺序为5'-mraZ-mraW-ftsI-murE-hyp1-murF-mraY-hyp2-murD-ftsW-murG-murC-ddl-ftsQ-ftsA-ftsZ-hyp3-3'。淋病奈瑟菌dcw基因簇的基因组织与革兰氏阴性杆菌（如大肠杆菌和流感嗜血杆菌）中观察到的更为相似，而与革兰氏阳性细菌不同。该基因簇的特征是有几个基因间隔区。与大肠杆菌相比，淋病奈瑟菌的dcw基因簇中缺少两个基因ftsL和envA，并且有三个假设基因是该基因簇所特有的。该基因簇两侧有两个由成对的奈瑟菌摄取序列组成的转录终止子，还包括四个内部终止子，其中三个是成对的奈瑟菌摄取序列。我们还发现，淋病奈瑟菌基因组上的一个重复序列（通常称为科雷亚元件）充当第四个转录终止子。通过逆转录PCR实验表明，所有终止序列均具有完全功能。通过引物延伸确定了ftsQ、ftsA和ftsZ上游的转录起始位点，并鉴定出六个启动子；三个启动子位于ftsZ上游的基因间隔区，两个位于ftsQ内ftsA的上游，一个位于ddl内ftsQ的上游。其中一些启动子在厌氧条件下优先使用。这些启动子的位置与大肠杆菌中描述的不同，表明转录调控存在差异。
