RpoB

rpoB is a bacterial gene that codes for part of an enzyme which synthesises RNA. Specifically, "rpoB" is the β subunit of the bacterial RNA polymerase. It is the subunit which possesses the polymerase activity, that is, it catalyzes the synthesis of RNA. Some anti-bacterial drugs (most importantly, rifampicin) kill bacteria by targetting this enzyme.

"rpoB" is a highly conserved enzyme contained by many bacteria, including Mycobacterium tuberculosis. It is the target of the antibiotic, rifampicin. Mutations in this gene are the main mechanism of resistance to rifampicin. [cite journal|author=Kapur V, Li LL, Iordanescu S, "et al."|title=Characterization by automated DNA sequencing of mutations in the gene (rpoB) encoding the RNA polymerase beta subunit in rifampin-resistant "Mycobacterium tuberculosis" strains from New York City and Texas|journal=J Clin Microbiol|year=1994|volume=32|issue=4|pages=1095–1098|url=http://jcm.asm.org/cgi/content/abstract/32/4/1095] cite journal|author=Wichelhaus TA, Schäfer V, Brade V, Böddinghaus B|title=Molecular characterization of rpoB mutations conferring cross-resistance to rifamycins on methicillin-resistant "Staphylococcus aureus"|journal=Antimicrob Agents Chemother|year=1999|pages=2813–2816|volume=43|issue=11]

A probe for "rpoB" can detect mutations in the gene that confer rifampicin resistance. For "Mycobacterium tuberculosis", the resistance-mutations most commonly found are at codons 531, 526 and 516 (in decreasing order of frequency), [cite journal|Mokrousov I, Otten T, Vyshnevskiy B, Narvskaya O|title=Allele-specific rpoB PCR assays for detection of rifampin-resistant "Mycobacterium tuberculosis" in sputum smears|journal=Antimicrob Agents Chemother|year=2003|pages=2231–2235|volume=47|issue=7|doi=10.1128/AAC.47.7.2231-2235.2003] in an area known as the "rifampicin resistance determining region". [cite journal|author=Telenti A, Imboden P, Marchesi F, "et al."|title=Detection of rifampicin-resistance mutations in "Mycobacterium tuberculosis"|journal=Lancet|year=1993|volume=341|issue=8846|pages=647–50|pmid=8095569] For "Staphylococcus aureus", the most commonly identified mutation is at codon 481. Gene probes are commonly used to guide tuberculosis treatment when drug-resistant tuberculosis is suspected.

References

External links

*