Conjugation of extrachromosomal replicons of Rhodococcus erythropolis AN12

Bacteria belonging to the Gram-positive actinomycete species, Rhodococcus erythropolis, are diverse not only in terms of metabolic potentials but the plasmids they encode. Pulsed-field gel electrophoresis (PFGE) revealed three previously uncharacterized megaplasmids in the genome of Rhodococcus erythropolis AN12. These megaplasmids, pREA400, pREA250 and pREA100, migrate at approximately 400 kb, 250 kb and 100 kb, respectively. Genetic screening of an AN12 transposon insertion library showed that two megaplasmids, pREA400 and pREA250, are conjugative. It is known for other bacterial systems that a relaxase encoded by the traA gene is required to initiate DNA transfer during plasmid conjugation. Sequences adjacent to the transposon insertion in megaplasmid pREA400 revealed a putative traA-like open reading frame. A novel site-specific gene disruption method was developed to generate a traA mutation in AN12, which allowed us to address the role of the traA gene for Rhodococcus megaplasmid conjugation. We found that the AN12 traA mutant is no longer capable of transferring the pREA400 megaplasmid to Rhodococcus erythropolis SQ1. It was shown previously that the R. erythropolis AN12 genome harbors a 6.3 kb cryptic plasmid called pAN12.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Yang, Joyce Chun-Yi

Advisor dc:contributor.advisor

• Anthony J. Sinskey.

• Biology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/34575

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/34575