Gasc Anne-Marie, Giammarinaro Philippe, Richter Stefan, Sicard Michel
Laboratoire de Microbiologie et de Génétique Moléculaire du CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France.
Max-Planck-Institut für Molekulare Genetik, Ihnestr. 73, D-14195 Berlin, Germany.
Microbiology (Reading). 1998 Feb;144 ( Pt 2):433-439. doi: 10.1099/00221287-144-2-433.
The dnaA gene region of Streptococcus pneumoniae was cloned and sequenced. A tRNA gene, seven ORFs and three DnaA box clusters were identified. The order of the genes and intergene regions found was tRNA(Arg)-orf1-DnaA box cluster 3-htrA-spoOJ-DnaA box cluster 2-dnaA-DnaA box cluster 1-dnaN-orfX-orfY. Five ORFs are homologous to known bacterial genes. The tRNA(Arg) gene and orf1, also called orfL, have already been described in pneumococci and have been reported to be preceded by the competence regulation locus comCDE. In Escherichia coli, htrA encodes a serine protease. In Bacillus subtilis, spoOJ plays a role in sporulation and partition. dnaA encodes an initiator replication protein, very well conserved in several bacteria and dnaN encodes the beta subunit of DNA polymerase III in E. coli. The function of orfX is unknown. The N-terminal part of another reading frame, orfY, revealed high homology with a GTP-binding protein, DnaA box clusters were found upstream and downstream from dnaA. The presence of two such clusters suggests that the chromosomal origin of S. pneumoniae is located within this region. The position of dnaA, and therefore the putative origin of replication, were localized on the physical map of S. pneumoniae.
对肺炎链球菌的dnaA基因区域进行了克隆和测序。鉴定出一个tRNA基因、七个开放阅读框（ORF）和三个DnaA框簇。所发现的基因和基因间区域的顺序为tRNA(Arg)-orf1-DnaA框簇3-htrA-spoOJ-DnaA框簇2-dnaA-DnaA框簇1-dnaN-orfX-orfY。五个开放阅读框与已知的细菌基因同源。tRNA(Arg)基因和orf1（也称为orfL）已在肺炎链球菌中被描述，据报道其前面有感受态调节基因座comCDE。在大肠杆菌中，htrA编码一种丝氨酸蛋白酶。在枯草芽孢杆菌中，spoOJ在孢子形成和细胞分裂中起作用。dnaA编码一种起始复制蛋白，在几种细菌中高度保守，而dnaN在大肠杆菌中编码DNA聚合酶III的β亚基。orfX的功能未知。另一个阅读框orfY的N端部分与一种GTP结合蛋白显示出高度同源性，在dnaA的上游和下游发现了DnaA框簇。两个这样的簇的存在表明肺炎链球菌的染色体起源位于该区域内。确定了dnaA的位置，因此也确定了推定的复制起点在肺炎链球菌的物理图谱上的位置。
