title: Genetic characterisation of a whiB7 mutant of a Mycobacterium tuberculosis clinical strain.
abstract: Mycobacterium tuberculosis is naturally resistant to clarithromycin (CLR). The genes Rv3197A (whiB7) and Rv1988 (ermMT) have been shown to be involved in the resistant phenotype. In this study, a CLR-susceptible M. tuberculosis clinical strain was identified, designated as DS3214, and the nucleotide sequences and expression profiles of whiB7 and ermMT were investigated. The results revealed that strain DS3214 contained a one nucleotide deletion in whiB7, leading to a truncated peptide. Expression of whiB7 was low, whereas comparable expression of ermMT was determined compared with the reference strain M. tuberculosis H37Rv. Overexpression of the mutant whiB7 in M. tuberculosis H37Ra did not increase the minimum inhibitory concentration (MIC) to CLR or kanamycin, indicating the defect of the mutant WhiB7. The CLR-susceptible M. tuberculosis clinical strain, whose whiB7 is naturally mutated, was first described in this study and whiB7 has been shown to play a role in the CLR-susceptible phenotype.
authors.affiliation: Tuberculosis Research Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani 12120, Thailand.
authors.forename: Saradee
authors.initials: S
authors.lastname: Warit
authors.affiliation: Department of Biology, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand; Bioenergy Research Unit, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
authors.forename: Saranya
authors.initials: S
authors.lastname: Phunpruch
authors.affiliation: Department of Biology, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
authors.forename: Chaitas
authors.initials: C
authors.lastname: Jityam
authors.affiliation: Tuberculosis Research Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani 12120, Thailand.
authors.forename: Sarinya
authors.initials: S
authors.lastname: Jaitrong
authors.affiliation: Tuberculosis Research Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani 12120, Thailand.
authors.forename: Pamaree
authors.initials: P
authors.lastname: Billamas
authors.affiliation: Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
authors.forename: Angkana
authors.initials: A
authors.lastname: Chaiprasert
authors.affiliation: Tuberculosis Research Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani 12120, Thailand; Department of Microbiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Prasit
authors.initials: P
authors.lastname: Palittapongarnpim
authors.affiliation: Tuberculosis Research Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani 12120, Thailand. Electronic address: therdsak@biotec.or.th.
authors.forename: Therdsak
authors.initials: T
authors.lastname: Prammananan
keywords: Macrolide; Methyltransferase; Mycobacterium; Resistance mechanism