Transcription regulation of the Escherichia coli pcnB gene coding for poly(A) polymerase I: roles of ppGpp, DksA and sigma factors.
Poly(A) polymerase I (PAP I), encoded by the pcnB gene, is a major enzyme responsible for RNA polyadenylation in Escherichia coli, a process involved in the global control of gene expression in this bacterium through influencing the rate of transcript degradation. Recent studies have suggested a complicated regulation of pcnB expression, including a complex promoter region, a control at the level of translation initiation and dependence on bacterial growth rate. In this report, studies on transcription regulation of the pcnB gene are described. Results of in vivo and in vitro experiments indicated that (a) there are three σ(70)-dependent (p1, pB, and p2) and two σ(S)-dependent (pS1 and pS2) promoters of the pcnB gene, (b) guanosine tetraphosphate (ppGpp) and DksA directly inhibit transcription from pB, pS1 and pS2, and (c) pB activity is drastically impaired at the stationary phase of growth. These results indicate that regulation of the pcnB gene transcription is a complex process, which involves several factors acting to ensure precise control of PAP I production. Moreover, inhibition of activities of pS1 and pS2 by ppGpp and DksA suggests that regulation of transcription from promoters requiring alternative σ factors by these effectors of the stringent response might occur according to both passive and active models.
Nadratowska-Wesołowska
Beata
B
Department of Molecular Biology, University of Gdańsk, Kładki 24, 80-822 Gdańsk, Poland.
Słomińska-Wojewódzka
Monika
M
Łyzeń
Robert
R
Wegrzyn
Alicja
A
Szalewska-Pałasz
Agnieszka
A
Wegrzyn
Grzegorz
G
D001483:Base Sequence; D018983:DNA Footprinting; D017931:DNA Primers; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D048168:Escherichia coli K12 / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D011062:Polynucleotide Adenylyltransferase / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011755:Pyrophosphatases / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics*; D014158:Transcription, Genetic
D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D012808:Sigma Factor; C090751:dksA protein, E coli; D011062:Polynucleotide Adenylyltransferase; C063643:pcnB protein, E coli; C027627:guanosine-3',5'-bis(diphosphate) 3'-pyrophosphatase; D011755:Pyrophosphatases