An unsubstituted C2 hydrogen of adenine is critical and sufficient at the -11 position of a promoter to signal base pair deformation.
The conserved A:T base pair at the -11 position of the promoters in Escherichia coli is very sensitive to substitutions. In vitro transcription with the galP1 promoter having a natural or unnatural base in either strand at position -11 showed that only a purine base with no side group at C2 in the nontemplate strand is transcriptionally potent; neither a purine with an amino group at C2 nor a pyrimidine support transcription. The amino group at C6 in the omnipresent adenine at -11 does not play any role in promoting transcription. The nature of the base, complementary or noncomplementary, at -11 in the template strand also does not influence transcription. We propose that the adenine, by becoming extrahelical, interacts with an amino acid(s) of the 2.3-2.4 region of sigma for which an unsubstituted C2 hydrogen is critical.
Lee
Hee Jung
HJ
Department of Biology, College of Natural Sciences, Chungnam National University, Taejon 305-764, Republic of Korea.
Lim
Heon Man
HM
Adhya
Sankar
S
D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D001483:Base Sequence; D004247:DNA / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000235:genetics; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D009841:Oligonucleotides; D006859:Hydrogen; D004247:DNA; D000225:Adenine