title: Molecular analysis of codon 548 in the rpoB gene involved in Mycobacterium tuberculosis resistance to rifampin.
abstract: Most Mycobacterium tuberculosis rifampin-resistant strains have been associated with mutations in an 81-bp rifampin resistance-determining region (RRDR) in the gene rpoB. However, if this region alone were targeted, rifampin-resistant strains with mutations outside the RRDR would not be detected. In this study, among 51 rifampin-resistant clinical isolates analyzed by sequencing 1,681-bp-long DNA fragments containing the RRDR, 47 isolates contained mutations within the RRDR, three isolates contained mutations both within and outside the RRDR, and only one isolate had a single missense mutation (Arg548His) located outside the RRDR. A drug susceptibility test of recombinant Mycobacterium smegmatis and M. tuberculosis isolates carrying mutated rpoB (Arg548His) showed an increased MIC for rifampin compared to that of the control strains. Modeling of the Arg548His mutant RpoB-DNA complex revealed that the His548 side chain formed a more stable hydrogen bond structure than did Arg548, reducing the flexibility of the rifampin-resistant cluster II region of RpoB, suggesting that the RpoB Arg548His mutant does not effectively interact with rifampin and results in bacterial resistance to the drug. This is the first report on the relationship between the mutation in codon 548 of RpoB and rifampin resistance in tuberculosis. The novel mutational profile of the rpoB gene described here will contribute to the comprehensive understanding of rifampin resistance patterns and to the development of a useful tool for simple and rapid drug susceptibility tests.
authors.affiliation: Department of Laboratory Medicine and Biotechnology, Tzu Chi University, College of Medicine, Hualien, Taiwan, Republic of China.
authors.forename: Yu-Tze
authors.initials: YT
authors.lastname: Horng
authors.affiliation: Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan, Republic of China Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei, Taiwan, Republic of China.
authors.forename: Wen-Yih
authors.initials: WY
authors.lastname: Jeng
authors.affiliation: Department of Internal Medicine, Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi, Taiwan National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Miaoli, Taiwan, Republic of China.
authors.forename: Yih-Yuan
authors.initials: YY
authors.lastname: Chen
authors.affiliation: Department of Laboratory Medicine and Biotechnology, Tzu Chi University, College of Medicine, Hualien, Taiwan, Republic of China.
authors.forename: Che-Hung
authors.initials: CH
authors.lastname: Liu
authors.affiliation: National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Miaoli, Taiwan, Republic of China.
authors.forename: Horng-Yunn
authors.initials: HY
authors.lastname: Dou
authors.affiliation: Department of Internal Medicine, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan, Republic of China.
authors.forename: Jen-Jyh
authors.initials: JJ
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine and Biotechnology, Tzu Chi University, College of Medicine, Hualien, Taiwan, Republic of China.
authors.forename: Kai-Chih
authors.initials: KC
authors.lastname: Chang
authors.affiliation: Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Chung-Li, Taiwan, Republic of China.
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Chien
authors.affiliation: Department of Laboratory Medicine and Biotechnology, Tzu Chi University, College of Medicine, Hualien, Taiwan, Republic of China pcsoo@mail.tcu.edu.tw.
authors.forename: Po-Chi
authors.initials: PC
authors.lastname: Soo
mesh_terms: D000595:Amino Acid Sequence; D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D003062:Codon / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics*; D012293:Rifampin / Q000494:pharmacology*; D014376:Tuberculosis / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000904:Antibiotics, Antitubercular; D001426:Bacterial Proteins; D003062:Codon; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin