MacRae Ian J, Segel Irwin H, Fisher Andrew J
Section of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, California 95616, USA.
Nat Struct Biol. 2002 Dec;9(12):945-9. doi: 10.1038/nsb868.
The structure of the cooperative hexameric enzyme ATP sulfurylase from Penicillium chrysogenum bound to its allosteric inhibitor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS), was determined to 2.6 A resolution. This structure represents the low substrate-affinity T-state conformation of the enzyme. Comparison with the high substrate-affinity R-state structure reveals that a large rotational rearrangement of domains occurs as a result of the R-to-T transition. The rearrangement is accompanied by the 17 A movement of a 10-residue loop out of the active site region, resulting in an open, product release-like structure of the catalytic domain. Binding of PAPS is proposed to induce the allosteric transition by destabilizing an R-state-specific salt linkage between Asp 111 in an N-terminal domain of one subunit and Arg 515 in the allosteric domain of a trans-triad subunit. Disrupting this salt linkage by site-directed mutagenesis induces cooperative inhibition behavior in the absence of an allosteric effector, confirming the role of these two residues.
产黄青霉的协同六聚体酶ATP硫酸化酶与其变构抑制剂3'-磷酸腺苷-5'-磷酸硫酸酯（PAPS）结合的结构已确定，分辨率为2.6埃。该结构代表了该酶的低底物亲和力T态构象。与高底物亲和力R态结构的比较表明，由于R到T的转变，结构域发生了大规模的旋转重排。这种重排伴随着一个10个残基的环从活性位点区域向外移动17埃，导致催化结构域呈现出一种开放的、类似产物释放的结构。有人提出，PAPS的结合通过破坏一个亚基N端结构域中的Asp 111与反式三联体亚基变构结构域中的Arg 515之间的R态特异性盐键来诱导变构转变。通过定点诱变破坏这种盐键会在没有变构效应物的情况下诱导协同抑制行为，证实了这两个残基的作用。
