Ebright R H, Cossart P, Gicquel-Sanzey B, Beckwith J
Proc Natl Acad Sci U S A. 1984 Dec;81(23):7274-8. doi: 10.1073/pnas.81.23.7274.
Previously, we reported that substitution of Glu-181 of the catabolite gene activator protein (CAP) by lysine, leucine, or valine results in a protein that has specificity for A X T base pairs at positions 7 and 16 of the DNA recognition site, rather than G X C base pairs as is the case with the wild-type CAP. In this paper, we deduce from these genetic data both (i) the specific chemical interactions by which amino acid side chains at position 181 interact with base pairs 7 and 16 and (ii) the precise alignment between the structures of the CAP and DNA in the intermolecular CAP-DNA complex. Our analysis supports the idea that the two symmetry-related F alpha-helices of the CAP dimer interact with successive major grooves of right-handed B-type DNA [Pabo, C. & Lewis, M. (1982) Nature (London) 298, 443-447; and Steitz, T., Weber, I. & Matthew, J. (1983) Cold Spring Harbor Symp. Quant. Biol. 47, 419-426].
此前,我们报道过,用赖氨酸、亮氨酸或缬氨酸取代分解代谢基因激活蛋白(CAP)的第181位谷氨酸,会产生一种蛋白质,该蛋白质对DNA识别位点第7位和第16位的AXT碱基对具有特异性,而非像野生型CAP那样对GXC碱基对具有特异性。在本文中,我们从这些遗传数据中推断出:(i)第181位氨基酸侧链与第7位和第16位碱基对相互作用的具体化学相互作用;(ii)分子间CAP-DNA复合物中CAP与DNA结构之间的精确排列。我们的分析支持了这样一种观点,即CAP二聚体中两个对称相关的Fα螺旋与右手B型DNA的连续大沟相互作用[帕博,C.和刘易斯,M.(1982年)《自然》(伦敦)298,443 - 447;以及施泰茨,T.、韦伯,I.和马修,J.(1983年)《冷泉港定量生物学研讨会》47,419 - 426]。