Structure of catabolite gene activator protein at 2.9-A resolution. Incorporation of amino acid sequence and interactions with cyclic AMP.
Structure of catabolite gene activator protein at 2.9-A resolution. Incorporation of amino acid sequence and interactions with cyclic AMP.
复制标题
分解代谢物基因激活蛋白的结构，分辨率为 2.9-A。
DOI：
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发表时间：
1982
影响因子：
4.8
通讯作者：
T. Steitz
中科院分区：
文献类型：
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作者：
D. Mckay;I. Weber;T. Steitz
大肠杆菌分解代谢基因激活蛋白的氨基酸序列已被拟合到2.9A分辨率的电子密度图中。二聚体的每个亚基由两个结构不同的结构域组成。较大的NH2-末端结构域被认为与环状AMP结合，并形成亚基之间的所有接触。环状AMP完全埋在大结构域的“Beta Roll”结构和一个长的α螺旋之间；它与这两个亚基的残基发生重要的氢键作用。埋藏的Arg中的胍基与环状AMP的磷酸盐形成内部盐键。腺嘌呤的6-氨基同时与两个亚基相互作用。这种与两个亚基的相互作用以及环状GMP和环状IMP不能激活分解代谢基因激活蛋白的事实表明，环状AMP的结合可能会改变两个亚基的相对取向，进而改变跨越两个较小结构域的DNA结合部位的结构。小结构域中侧链的分布和性质不排除分解代谢基因激活蛋白与左手B-DNA结合的可能性。
The amino acid sequence of the Escherichia coli catabolite gene activator protein has been fit into a 2.9-A resolution electron density map. Each subunit of the dimer consists of two structurally distinct domains. The larger NH2-terminal domain is seen to bind cyclic AMP and forms all of the contacts between the subunits. The cyclic AMP is completely buried between the interior of the "beta roll" structure of the large domain and a long alpha helix; it makes important hydrogen-bonding interactions with residues from both subunits. The guanidinium group of a buried Arg makes an internal salt link with the phosphate of cyclic AMP. The 6-amino group of adenine interacts simultaneously with both subunits. This interaction with both subunits and the fact that cyclic GMP and cyclic IMP do not activate catabolite gene activator protein suggest that the binding of cyclic AMP may alter the relative orientation of the two subunits, which in turn would change the structure of a DNA binding site that is presumed to span the two smaller domains. The distribution and nature of side chains in the small domain do not rule out the possibility that catabolite gene activator protein binds to left-handed B-DNA.