Inhibition of chromosome replication in Mycobacterium smegmatis: effect of the rpmH-dnaA promoter region.
In a previous study a functional mycobacterial origin of replication, oriC, was isolated on a plasmid. However, it was found that origin function was inhibited by the presence of the adjacent dnaA gene or its regulatory region, so that plasmids containing both of these regions next to the origin did not yield transformants. This inhibition could be due either to overexpression of dnaA on a plasmid being toxic, the transcription of dnaA into the downstream origin topologically inhibiting its function, or to the DnaA boxes upstream of dnaA somehow interacting with the DnaA boxes in the origin to prevent its function. To distinguish between these possibilities, plasmids were constructed lacking different parts of the dnaA gene: the promoter, the DnaA boxes, or both. Additionally, the putative dnaA promoter region was replaced by mycobacterial sequences that exhibit weaker or null promoter activity. The results indicate that the rpmH-dnaA promoter region, but not the DnaA boxes, is the principal cause of the incompatibility observed and suggest that this region could be playing a role in the inhibition of chromosome replication.
Salazar
Leiria
L
Laboratorio de Genética Molecular, Centro de Microbiologı́a y Biologı́a Celular, Instituto Venezolano de Investigaciones Cientı́ficas, Apartado 21827, Caracas 1020A, Venezuela1.
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D020102:Mycobacterium smegmatis / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D018741:Replication Origin / Q000235:genetics; D014169:Transformation, Bacterial
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins