Comparison of promoter-specific events during transcription initiation in mycobacteria

DNA-protein interactions that occur during transcription initiation play an important role in regulating gene expression. To initiate transcription, RNA polymerase (RNAP) binds to promoters in a sequence-specific fashion. This is followed by a series of steps governed by the equilibrium binding and...

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Bibliographic Details
Published in:Microbiology (Society for General Microbiology) 2010-07, Vol.156 (Pt 7), p.1942-1952
Main Authors: China, Arnab, Tare, Priyanka, Nagaraja, Valakunja
Format: Article
Language:English
Subjects:
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Base Sequence
DNA-Directed RNA Polymerases - genetics
DNA-Directed RNA Polymerases - metabolism
Gene Expression Regulation, Bacterial
Kinetics
Molecular Sequence Data
Mycobacterium smegmatis - chemistry
Mycobacterium smegmatis - enzymology
Mycobacterium smegmatis - genetics
Promoter Regions, Genetic
Protein Binding
Transcription Initiation Site
Transcription, Genetic
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Summary:DNA-protein interactions that occur during transcription initiation play an important role in regulating gene expression. To initiate transcription, RNA polymerase (RNAP) binds to promoters in a sequence-specific fashion. This is followed by a series of steps governed by the equilibrium binding and kinetic rate constants, which in turn determine the overall efficiency of the transcription process. We present here the first detailed kinetic analysis of promoter-RNAP interactions during transcription initiation in the sigma(A)-dependent promoters P(rrnAPCL1), P(rrnB) and P(gyr) of Mycobacterium smegmatis. The promoters show comparable equilibrium binding affinity but differ significantly in open complex formation, kinetics of isomerization and promoter clearance. Furthermore, the two rrn promoters exhibit varied kinetic properties during transcription initiation and appear to be subjected to different modes of regulation. In addition to distinct kinetic patterns, each one of the housekeeping promoters studied has its own rate-limiting step in the initiation pathway, indicating the differences in their regulation.
ISSN:1350-0872
1465-2080
DOI:10.1099/mic.0.038620-0