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Abstract：
The crystal structure of cyclic AMP-catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP-DNA complex structures.
摘要：
据报道，含有氯化钴（II）和硫酸铵的大肠杆菌中的环状AMP-分解代谢激活蛋白（CAP）的晶体结构为1.97µ。不对称单元中的两个CAP亚基中的每一个都结合一个钴（II）离子，在每种情况下,由N-末端结构域残基His19、His21和Glu96加上通过晶体接触贡献的另外的酸性残基协调。三个鉴定的N末端结构域钴结合残基是CAP区域的一部分，该区域对于II类CAP依赖性启动子的转录激活很重要。硫酸根阴离子介导另外的晶格接触并占据对应于CAP-DNA复合物结构中的DNA主链磷酸盐位置的位点。
