The -35 sequence location and the Fis-sigma factor interface determine sigmas selectivity of the proP (P2) promoter in Escherichia coli.
The P2 promoter of proP, encoding a transporter for proline and glycine betaine in Escherichia coli, is a unique paradigm, where master regulators of different growth stages, Fis and sigma(S) (RpoS), collaborate to achieve promoter activation. It is also the only case described where Fis functions as class II transcriptional activator (centred at -41). Here we show that the degenerate -35 sequence, and the location of the Fis binding site, which forces a suboptimal 16 bp spacing between the -35 and -10 elements, allow only sigma(S) but not sigma(70) to function at proP (P2). Moreover, the interface between Fis and sigma(S) seems better suited to sigma(S), due to a single residue difference between sigma(S) and sigma(70). Nevertheless, Fis can activate RNA polymerase containing sigma(70) at a proP (P2) promoter variant, in which a typical sigma(70)-35 recognition sequence has been introduced at a 17 bp distance from the -10 hexamer. In summary, we elucidate the rules that govern sigma factor selectivity in the presence of a class II activator, provide new insight into transcriptional activation by Fis from this position, and clarify, why the proP (P2) promoter is precisely activated during a short time window of the growth cycle, when Fis and sigma(S) are both present.
Typas
Athanasios
A
Institut für Biologie, Mikrobiologie, Freie Universität Berlin, Königin-Luise-Str. 12-16, 14195 Berlin, Germany.
Stella
Stefano
S
Johnson
Reid C
RC
Hengge
Regine
R
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D035021:Factor For Inversion Stimulation Protein / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000378:metabolism; D016254:Mutagenesis, Insertional; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000737:chemistry / Q000378:metabolism*; D027981:Symporters / Q000235:genetics*; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; C501034:Fis protein, E coli; D046912:Multiprotein Complexes; C079244:ProP protein, E coli; D012808:Sigma Factor; D027981:Symporters; C069567:sigma factor KatF protein, Bacteria; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases