Role of glutamic acid-181 in DNA-sequence recognition by the catabolite gene activator protein (CAP) of Escherichia coli: altered DNA-sequence-recognition properties of [Val181]CAP and [Leu181]CAP.
AUTOR(ES)
Ebright, R H
RESUMO
It has been proposed that Glu-181 of the catabolite gene activator protein (CAP) makes direct contact with certain base pairs of the specific DNA site. We have purified wild-type CAP and two substituted CAP variants, [Val181]CAP and [Leu181]CAP, and have assessed the DNA-sequence-recognition properties in vitro with respect to positions 5, 6, 7, 8, and 16 of the DNA site. The data indicate that [Val181]CAP and [Leu181]CAP fail to discriminate between the consensus DNA base pair and the three non-consensus-DNA base pairs at 2-fold-related positions 7 and 16 of the DNA site. In contrast, [Val181]CAP and [Leu181]CAP retain the ability to discriminate between different base pairs at positions 5 and 8 of the DNA site. We conclude that Glu-181 of CAP makes a direct contact with 2-fold-related positions 7 and 16 of the DNA site, as proposed previously based on in vivo results. We propose that upon replacement of Glu-181 by valine or leucine, this contact is eliminated and is replaced by no other functional contact. We estimate that the contact by Glu-181 with each position contributes -0.7 kcal/mol to the total CAP-DNA binding free energy.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=299012Documentos Relacionados
- DNA-sequence recognition by CAP: role of the adenine N6 atom of base pair 6 of the DNA site.
- DNA-sequence specific recognition by a thiazole analogue of netropsin: a comparative footprinting study.
- DNA-sequence and metal-ion specificity of the formation of *H-DNA.
- Lysine 188 of the catabolite gene activator protein (CAP) plays no role in specificity at base pair 7 of the DNA half site.
- Identification of a contact between arginine-180 of the catabolite gene activator protein (CAP) and base pair 5 of the DNA site in the CAP-DNA complex.
