Schrapers Peer, Ilina Julia, Gregg Christina M, Mebs Stefan, Jeoung Jae-Hun, Dau Holger, Dobbek Holger, Haumann Michael
Department of Physics, Freie Universität Berlin, Berlin, Germany.
Institute of Biology, Structural Biology/Biochemistry, Humboldt-Universität zu Berlin, Berlin, Germany.
PLoS One. 2017 Feb 8;12(2):e0171039. doi: 10.1371/journal.pone.0171039. eCollection 2017.
Bacteria integrate CO2 reduction and acetyl coenzyme-A (CoA) synthesis in the Wood-Ljungdal pathway. The acetyl-CoA synthase (ACS) active site is a [4Fe4S]-[NiNi] complex (A-cluster). The dinickel site structure (with proximal, p, and distal, d, ions) was studied by X-ray absorption spectroscopy in ACS variants comprising all three protein domains or only the C-terminal domain with the A-cluster. Both variants showed two square-planar Ni(II) sites and an OH- bound at Ni(II)p in oxidized enzyme and a H2O at Ni(I)p in reduced enzyme; a Ni(I)p-CO species was induced by CO incubation and a Ni(II)-CH3- species with an additional water ligand by a methyl group donor. These findings render a direct effect of the N-terminal and middle domains on the A-cluster structure unlikely.
细菌在伍德-Ljungdal途径中整合二氧化碳还原和乙酰辅酶A（CoA）合成。乙酰辅酶A合成酶（ACS）的活性位点是一个[4Fe4S]-[NiNi]复合物（A簇）。通过X射线吸收光谱法研究了包含所有三个蛋白质结构域或仅包含具有A簇的C末端结构域的ACS变体中的二镍位点结构（具有近端、p和远端、d离子）。两种变体在氧化酶中均显示出两个平面正方形的Ni（II）位点和一个与Ni（II）p结合的OH-，在还原酶中显示出一个与Ni（I）p结合的H2O；通过CO孵育诱导出Ni（I）p-CO物种，通过甲基供体诱导出带有额外水配体的Ni（II）-CH3-物种。这些发现使得N末端和中间结构域对A簇结构产生直接影响的可能性不大。
