Abstract:
:Research on tuberculosis and leprosy was revolutionized by the development of a plasmid transformation system in the fast-growing surrogate, Mycobacterium smegmatis. This transformation system was made possible by the successful isolation of a M. smegmatis mutant strain mc(2)155, whose efficient plasmid transformation (ept) phenotype supported the replication of Mycobacterium fortuitum pAL5000 plasmids. In this report, we identified the EptC gene, the loss of which confers the ept phenotype. EptC shares significant amino acid sequence homology and domain structure with the MukB protein of Escherichia coli, a structural maintenance of chromosomes (SMC) protein. Surprisingly, M. smegmatis has three paralogs of SMC proteins: EptC and MSMEG_0370 both share homology with Gram-negative bacterial MukB; and MSMEG_2423 shares homology with Gram-positive bacterial SMCs, including the single SMC protein predicted for Mycobacterium tuberculosis and Mycobacterium leprae. Purified EptC was shown to bind ssDNA and stabilize negative supercoils in plasmid DNA. Moreover, an EptC-mCherry fusion protein was constructed and shown to bind to DNA in live mycobacteria, and to prevent segregation of plasmid DNA to daughter cells. To our knowledge, this is the first report of impaired plasmid maintenance caused by a SMC homolog, which has been canonically known to assist the segregation of genetic materials.
journal_name
Proc Natl Acad Sci U S Aauthors
Panas MW,Jain P,Yang H,Mitra S,Biswas D,Wattam AR,Letvin NL,Jacobs WR Jrdoi
10.1073/pnas.1414207111subject
Has Abstractpub_date
2014-09-16 00:00:00pages
13264-71issue
37eissn
0027-8424issn
1091-6490pii
1414207111journal_volume
111pub_type
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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