5zx2
From Proteopedia
Mycobacterium tuberculosis RNA polymerase transcription initiation complex with ECF sigma factor sigma H and 7nt RNA
Structural highlights
Function[RPOC_MYCTU] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_01322][1] [RPOB_MYCTU] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_01321] [RPOA_MYCTU] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_00059][2] [RPOZ_MYCTU] 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.[3] [SIGH_MYCTU] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. Extracytoplasmic function (ECF) sigma factors are held in an inactive form by a cognate anti-sigma factor (RshA) until released. This sigma factor is involved in heat shock and oxidative stress responses; it positively regulates the expression of itself, sigE, sigB and a number of transcriptional regulators as well as other effectors of heat and oxidative stress, leading to direct and indirect control of up to 25% of the bacterial genome. Modulates expression of host genes for intercrine beta (chemokine CC) and apoptosis, altering the host immune response.[4] [5] [6] [7] Publication Abstract from PubMedBacterial RNA polymerase employs extra-cytoplasmic function (ECF) sigma factors to regulate context-specific gene expression programs. Despite being the most abundant and divergent sigma factor class, the structural basis of ECF sigma factor-mediated transcription initiation remains unknown. Here, we determine a crystal structure of Mycobacterium tuberculosis (Mtb) RNAP holoenzyme comprising an RNAP core enzyme and the ECF sigma factor sigma(H) (sigma(H)-RNAP) at 2.7 A, and solve another crystal structure of a transcription initiation complex of Mtb sigma(H)-RNAP (sigma(H)-RPo) comprising promoter DNA and an RNA primer at 2.8 A. The two structures together reveal the interactions between sigma(H) and RNAP that are essential for sigma(H)-RNAP holoenzyme assembly as well as the interactions between sigma(H)-RNAP and promoter DNA responsible for stringent promoter recognition and for promoter unwinding. Our study establishes that ECF sigma factors and primary sigma factors employ distinct mechanisms for promoter recognition and for promoter unwinding. Structural basis for transcription initiation by bacterial ECF sigma factors.,Li L, Fang C, Zhuang N, Wang T, Zhang Y Nat Commun. 2019 Mar 11;10(1):1153. doi: 10.1038/s41467-019-09096-y. PMID:30858373[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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