5vi8
From Proteopedia
Structure of a mycobacterium smegmatis transcription initiation complex with an upstream-fork promoter fragment
Structural highlights
Function[A0QW02_MYCS2] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. This sigma factor is the primary sigma factor during exponential growth.[SAAS:SAAS00535554] [RPOB_MYCS2] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. This subunit often mutates to generate rifampicin (Rif) resistance. Interaction with RbpA partially restores Rif-inhibited transcription; once the subunit is Rif-resistant however RbpA no longer stimulates transcription.[HAMAP-Rule:MF_01321][1] [RPOA_MYCS2] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_00059][2] [RBPA_MYCS2] Binds to RNA polymerase (RNAP), probably stimulating transcriptions from principal, but not alternative sigma factor promoters (By similarity). Partially restores transcription in the presence of rifampicin (Rif) in vitro; overexpression leads to an increase in the Rif tolerance in vivo, with smaller colonies. Seems to act by removing Rif from its binding site and preventing its further binding. No longer stimulates transcription in Rif-resistant RNA polymerase (with mutations in rpoB).[3] [4] [RPOC_MYCS2] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_01322][5] [RPOZ_MYCS2] Promotes RNA polymerase assembly. Latches the N- and C-terminal regions of the beta' subunit thereby facilitating its interaction with the beta and alpha subunits.[HAMAP-Rule:MF_00366][6] Publication Abstract from PubMedThe mycobacteria RNA polymerase (RNAP) is a target for antimicrobials against tuberculosis, motivating structure/function studies. Here we report a 3.2 A-resolution crystal structure of a Mycobacterium smegmatis (Msm) open promoter complex (RPo), along with structural analysis of the Msm RPo and a previously reported 2.76 A-resolution crystal structure of an Msm transcription initiation complex with a promoter DNA fragment. We observe the interaction of the Msm RNAP alpha-subunit C-terminal domain (alphaCTD) with DNA, and we provide evidence that the alphaCTD may play a role in Mtb transcription regulation. Our results reveal the structure of an Actinobacteria-unique insert of the RNAP beta' subunit. Finally, our analysis reveals the disposition of the N-terminal segment of Msm sigmaA, which may comprise an intrinsically disordered protein domain unique to mycobacteria. The clade-specific features of the mycobacteria RNAP provide clues to the profound instability of mycobacteria RPo compared with E. coli. Structural insights into the mycobacteria transcription initiation complex from analysis of X-ray crystal structures.,Hubin EA, Lilic M, Darst SA, Campbell EA Nat Commun. 2017 Jul 13;8:16072. doi: 10.1038/ncomms16072. PMID:28703128[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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