Mapping CooA.RNA polymerase interactions. Identification of activating regions 2 and 3 in CooA, the co-sensing transcriptional activator.
CooA is a CO-sensing protein that activates the transcription of genes encoding the CO-oxidation (coo) regulon, whose polypeptide products are required for utilizing CO as an energy source in Rhodospirillum rubrum. CooA binds to a position overlapping the -35 element of the P(cooF) promoter, similar to the arrangement of class II CRP (cAMP receptor protein)- and FNR (fumarate and nitrate reductase activator protein)-dependent promoters when expressed in Escherichia coli. Gain-of-function CooA variants were isolated in E. coli following mutagenesis of the portion of cooA encoding the effector-binding domain. Some of the mutations affect regions of CooA that are homologous to the activating regions (AR2 and AR3) previously identified in CRP and FNR, whereas others affect residues that lie in a region of CooA between AR2 and AR3. These CooA variants are comparable to wild-type (WT) CooA in DNA binding affinity in response to CO but differ in transcription activation, presumably because of altered interactions with E. coli RNA polymerase. Based on predictions of similarity to CRP and FNR, loss-of-function CooA variants were obtained in the AR2 and AR3 regions that have minimal transcriptional activity, yet have WT-like DNA binding affinities in response to CO. This study demonstrates that WT CooA contains AR2- and AR3-like surfaces that are required for optimal transcription activation.
Leduc
J
J
Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
Thorsteinsson
M V
MV
Gaal
T
T
Roberts
G P
GP
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002248:Carbon Monoxide / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D014644:Genetic Variation; D006420:Hemeproteins / Q000235:genetics / Q000378:metabolism*; D008957:Models, Genetic; D008958:Models, Molecular; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D012247:Rhodospirillum rubrum / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D001426:Bacterial Proteins; C108776:CooA protein, Rhodospirillum rubrum; D004268:DNA-Binding Proteins; D006420:Hemeproteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D002248:Carbon Monoxide; D012321:DNA-Directed RNA Polymerases