The Escherichia coli RNA polymerase alpha subunit linker: length requirements for transcription activation at CRP-dependent promoters.
The C-terminal domain of the Escherichia coli RNA polymerase alpha subunit (alphaCTD) plays a key role in transcription initiation at many activator-dependent promoters. This domain is connected to the N-terminal domain by an unstructured linker, which is proposed to confer a high degree of mobility on alphaCTD. To investigate the role of this linker in transcription activation we tested the effect of altering the linker length on promoters dependent on the cyclic AMP receptor protein (CRP). Short deletions within the alpha linker decrease CRP-dependent transcription at a Class I promoter while increasing the activity of a Class II promoter. Linker extension impairs CRP-dependent transcription from both promoters, with short extensions exerting a more marked effect on the Class II promoter. Activation at both classes of promoter was shown to remain dependent upon activating region 1 of CRP. These results show that the response to CRP of RNA polymerase containing linker-modified alpha subunits is class specific. These observations have important implications for the architecture of transcription initiation complexes at CRP-dependent promoters.
Meng
W
W
Division of Molecular and Genetic Medicine, University of Sheffield Medical School, Sheffield S10 2RX, UK.
Savery
N J
NJ
Busby
S J
SJ
Thomas
M S
MS
D000595:Amino Acid Sequence; D001483:Base Sequence; D002373:Cyclic AMP Receptor Protein / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D005798:Genes, Bacterial; D008954:Models, Biological; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation
D002373:Cyclic AMP Receptor Protein; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases; C113275:RNA polymerase alpha subunit