Structural highlights
Publication Abstract from PubMedRNA polymerase binding protein A (RbpA), encoded by Rv2050, is specific to the actinomycetes, where it is highly conserved. In the pathogen Mycobacterium tuberculosis, RbpA is essential for growth and survival. RbpA binds to the beta subunit of the RNA polymerase where it activates transcription by unknown mechanisms, and it may also influence the response of M. tuberculosis to the current frontline anti-tuberculosis drug rifampicin. Here we report the solution structure of RbpA and identify the principle sigma factor sigmaA, and the stress-induced sigmaB, as interaction partners. The protein has a central ordered domain with a conserved hydrophobic surface that may be a potential protein interaction site. The N- and C- termini are highly dynamic and are involved in the interaction with the sigma factors. RbpA forms a tight complex with the N-terminal domain of sigmaB via its N- and C-terminal regions. The interaction with sigma factors may explain how RbpA stabilises sigma subunit binding to the core RNA polymerase and thereby promotes initiation complex formation. RbpA could therefore influence the competition between principal and alternative sigma factors and hence the transcription profile of the cell. Mycobacterium tuberculosis RNA polymerase binding protein A (RbpA) and its interactions with sigma factors.,Bortoluzzi A, Muskett FW, Waters LC, Addis PW, Rieck B, Munder T, Schleier S, Forti F, Ghisotti D, Carr MD, O'Hare HM J Biol Chem. 2013 Apr 10. PMID:23548911[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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