4xlr
Crystal structure of T.aquaticus transcription initiation complex with CarD containing bubble promoter and RNACrystal structure of T.aquaticus transcription initiation complex with CarD containing bubble promoter and RNA
Structural highlights
Function[RPOZ_THEAQ] 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.[1] [SIGA_THEAQ] 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.[HAMAP-Rule:MF_00963][2] [3] Publication Abstract from PubMedA key point to regulate gene expression is at transcription initiation, and activators play a major role. CarD, an essential activator in Mycobacterium tuberculosis, is found in many bacteria, including Thermus species, but absent in Escherichia coli. To delineate the molecular mechanism of CarD, we determined crystal structures of Thermus transcription initiation complexes containing CarD. The structures show CarD interacts with the unique DNA topology presented by the upstream double-stranded/single-stranded DNA junction of the transcription bubble. We confirm that our structures correspond to functional activation complexes, and extend our understanding of the role of a conserved CarD Trp residue that serves as a minor groove wedge, preventing collapse of the transcription bubble to stabilize the transcription initiation complex. Unlike E. coli RNAP, many bacterial RNAPs form unstable promoter complexes, explaining the need for CarD. CarD uses a minor groove wedge mechanism to stabilize the RNA polymerase open promoter complex.,Bae B, Chen J, Davis E, Leon K, Darst SA, Campbell EA Elife. 2015 Sep 8;4. doi: 10.7554/eLife.08505. PMID:26349034[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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