title: Characterization of the functional replication origin of Mycobacterium tuberculosis.
abstract: The gene order in the 5kb Mycobacterium tuberculosis dnaA region is rnpA, rpmH, dnaA, dnaN and recF. We show that M. tuberculosis DNA fragment containing the dnaA-dnaN intergenic region functioned as oriC, i.e., allowed autonomous replication to otherwise nonreplicative plasmids, in M. tuberculosis H37Ra (H37Ra), avirulent strain of M. tuberculosis, and in Mycobacterium bovis BCG (BCG), a closely related, slowly growing mycobacterial strain. Removal of Escherichia coli plasmid replication origin (ColE1) from the M. tuberculosis oriC plasmids did not abolish their ability to function as oriC, confirming that the autonomous replication activity of these plasmids is due to the presence of the DNA fragment containing the dnaA-dnaN intergenic region. Deletion analyses revealed that the minimal oriC DNA fragment is 814bp. The copy number of M. tuberculosis oriC plasmids containing ColE1 ori relative to chromosomal oriC is one and the 5' flanking region of minimal oriC contains features that support stable autonomous replication. The M. tuberculosis oriC did not function in rapidly growing mycobacterial species such as M. smegmatis. M. smegmatis oriC functioned only in M. fortuitum, but not in any of the slowly growing mycobacterial species such as M. tuberculosis and BCG. Together these data suggest that the replication initiation mechanisms in the slowly growing Mycobacteria are similar and probably different from those in the rapidly growing Mycobacteria and vice versa.
authors.affiliation: Department of Biochemistry, The University of Texas Health Center at Tyler, Tyler, TX 75708-3154, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Qin
authors.forename: M V
authors.initials: MV
authors.lastname: Madiraju
authors.forename: M
authors.initials: M
authors.lastname: Rajagopalan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D010957:Plasmids; D018741:Replication Origin; D017384:Sequence Deletion
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria