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首页> 外文期刊>Biochemistry >The (alpha(FC)-C-357)(3)(beta(RC)-C-372)(3)gamma subcomplex of the F-1-ATPase from the thermophilic bacillus PS3 has altered ATPase activity after cross-linking alpha and beta subunits at noncatalytic site interfaces
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The (alpha(FC)-C-357)(3)(beta(RC)-C-372)(3)gamma subcomplex of the F-1-ATPase from the thermophilic bacillus PS3 has altered ATPase activity after cross-linking alpha and beta subunits at noncatalytic site interfaces

机译：嗜热芽孢杆菌PS3的F-1-ATPase的（alpha（FC）-C-357）（3）（beta（RC）-C-372）（3）γ亚复合物在交联alpha后改变了ATPase活性和β亚基在非催化位点界面

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摘要

In crystal structures of bovine MF1, the side chains of alphaF(357) and betaR(372) are near the adenines of nucleotides bound to noncatalytic sites. To determine if during catalysis these side chains must pass through the different arrangements in which they are present in crystal structures, the catalytic proper-ties of the (alphaF(357)C)(3)(betaR(372))(3gamma) subcomplex of the TF1-ATPase were characterized before and after crosslinking the introduced cysteines with CuCl2. The unmodified mutant enzyme hydrolyzes MgATP at 50% the rate exhibited by wild type. Detailed comparison of the catalytic properties of the double mutant enzvme before and after cross-linking with those of the wild-type subcomplex. revealed the following.Before cross-linking, (alphaF(357)C)(3)(betaR(372)C)(3)gamma subcomplex the less tendency than wild type to release the inhibitory MgADP entrapped in a catalytic site during turnover when MgATP binds to noncatalytic sites. Following cross-linking, ATPase activity is reduced 5-fold, and inhibitory MgADP entrapped in a catalytic site during turnover does not release under conditions wherein binding of ATP to noncatalytic sites of the wild-type enzyme promotes release of MgADP from the affected catalytic site. When assayed in the presence of lauryldimethylaraine oxide, which prevents turnover-dependent entrapment of inhibitory Mg,ADP in a catalytic site, ATPase activity of the cross-linked form is 47% that of the unmodified mutant enzyme. These results suggest that, during catalysis, the side chains of alphaF(357) and betaR(372) do not pass through the extremely different relative positions in which they exist at the three noncatalytic site interfaces in cnistal structures. [References: 40]
机译：在牛MF1的晶体结构中，alphaF（357）和betaR（372）的侧链靠近与非催化位点结合的核苷酸的腺嘌呤。若要确定是否在催化过程中这些侧链是否必须通过它们在晶体结构中存在的不同排列方式，（alphaF（357）C）（3）（betaR（372））（3γ）亚配合物的催化性质在引入的半胱氨酸与CuCl2交联之前和之后，对TF1-ATPase的特征进行了表征。未修饰的突变酶以野生型显示的速率水解MgATP的50％。与野生型亚复合物交联之前和之后，双突变体酶催化性能的详细比较。在交联之前，（αF（357）C）（3）（betaR（372）C）（3）γ亚复合物比野生型在释放时在周转期间释放捕获在催化位点的抑制性MgADP的趋势要小。 MgATP结合到非催化位点。交联后，ATPase活性降低了5倍，并且在ATP与野生型酶的非催化位点结合促进MgADP从受影响的催化位点释放的条件下，周转期间困在催化位点的抑制性MgADP不会释放。 。当在月桂基二甲基araine氧化物的存在下进行分析时，该氧化物可防止抑制性Mg，ADP在催化位点中依赖于周转性的滞留，该交联形式的ATPase活性为未修饰突变酶的47％。这些结果表明，在催化过程中，alphaF（357）和betaR（372）的侧链不会通过它们在中央结构的三个非催化位点界面处存在的相对不同的相对位置。 [参考：40]

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