Genetic and biochemical characterization of TraA, the relaxase of symbiotic plasmid pRetCFN42d from Rhizobium etli, is described. After purifying the relaxase domain (N265TraA), we demonstrated nic binding and cleavage activity in vitro and thus characterized for the first time the nick site (nic) of a plasmid in the family Rhizobiaceae. We studied the range of N265TraA relaxase specificity in ...

Five of the seven cases of vancomycin-resistant Staphylococcus aureus (VRSA) infection identified to date have occurred in southeastern Michigan. VRSA isolates from the four most recent cases (all from Michigan) were characterized. The vanA gene was localized to a single plasmid in each VRSA isolate. The pulsed-field gel electrophoresis patterns of chromosomal DNA and the restriction profile of...

P1 transduction has been used to perform a complementation analysis of a series of transfer-deficient mutants of Flac. The results define ten cistrons and are consistent with the results of a conjugational analysis presented in an accompanying report. Both sets of results are summarized here. Between them, they define eleven cistrons, traA through traK, necessary for conjugational deoxyribonucl...

An 11-kbp multicopy plasmid, pSN22, was isolated from Streptomyces nigrifaciens SN22. pSN22 is self-transmissible (conjugative), is maintained stably in S. lividans, and forms pocks in a wide range of Streptomyces strains. Mutational analyses showed that a fragment of pSN22 contained five genes involved in plasmid transfer and pock formation. traB was essential for plasmid transfer. traA was re...

Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 11, No. 2, February 2005 347 within SXTLAOS. However, the gene was not found in any of the proposed hot spot regions. The possibility that the trimethoprim resistance determinant is located on the chromosome outside the SXT element and cotransfers with the SXT in an Hfr-like manner cannot be ruled out (9). Therefore, additional hot spot regi...

Bacterial colonization of the upper respiratory tract is the first step in the pathogenesis of Haemophilus influenzae (Hi) infection. Haemophilus influenzae carriage rates vary between 25% and 84% in children, and colonization is a very dynamic process characterized by rapid bacterial turnover and carriage of multiple Hi strains (Trottier et al., 1989; Faden et al., 1991; Dhooge et al., 2000; S...

The mechanism of DNA transmission between distinct organisms has remained a subject of long-standing interest. Agrobacterium tumefaciens mediates the transfer of plant oncogenes in the form of a 25-kb T-DNA sector of a resident Ti plasmid. A growing body of evidence leading to the elucidation of the mechanism involved in T-DNA transfer comes from studies on the vir genes contained in six major ...

The mechanism of conjugal transfer of plasmids in Gram-negative and unicellular Gram-positive bacteria is commonly via a type IV secretion system (T4SS) [1]. The genes encoding the T4S proteins are usually arranged in a single operon or a few operons. In Gram-negative Agrobacterium tumefaciens, the T4SS is encoded by the virB and virD operons (11 and 5 genes, respectively) [2]. Streptomyces are...