Active-site gating regulates substrate selectivity in a chymotrypsin-like serine protease the structure of haemophilus influenzae immunoglobulin A1 protease.
Active-site gating regulates substrate selectivity in a chymotrypsin-like serine protease the structure of haemophilus influenzae immunoglobulin A1 protease.
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DOI：
10.1016/j.jmb.2009.04.041
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发表时间：
2009-06-12
影响因子：
5.6
通讯作者：
Holyoak, Todd
中科院分区：
文献类型：
--
作者：
Johnson, Troy A.;Qiu, Jiazhou;Plaut, Andrew G.;Holyoak, Todd
我们在这里报道了第一个1.75？分辨率的IgA蛋白水解酶家族成员的结构。这种蛋白酶是V型(自动转运蛋白)分泌系统的创始成员，被认为是表达该酶的细菌中的毒力决定因素。该酶的结构符合经典的自动转运蛋白的结构，在该转运蛋白中，蛋白质功能所必需的几个独特的结构域被附加到一个长达100ä的中心β-螺旋结构域上。研究发现，Ig A蛋白的N-末端结构域具有类胰凝乳酶的折叠。然而，这个催化结构域包含一个独特的环D，它延伸到活性部位上，作为盖子，门控底物访问。这些数据为已知的免疫球蛋白酶仅在免疫球蛋白完整折叠的情况下切割免疫球蛋白A1特有的P/S/T富含铰链肽的能力提供了结构基础。基于结构数据和分子模拟，提出了一个模型，该模型表明在没有免疫球蛋白结合的情况下，该IgA蛋白酶中独特的、扩展的环D立体地封闭了活性部位结合裂隙。只有在免疫球蛋白Fc结构域与β-螺旋脊柱上的另一个结构域(结构域2)之间形成的山谷中结合时，盖子才能稳定在开放的构象中。通过Fc结合的这种开放构象的稳定，随后允许铰链多肽进入活性部位，导致底物的识别和切割。
We report here the first structure of a member of the IgA protease family at 1.75Å resolution. This protease is a founding member of the Type V (autotransporter) secretion system and is considered a virulence determinant among the bacteria expressing the enzyme. The structure of the enzyme fits that of a classical autotransporter in which several unique domains necessary for protein function are appended to a central, 100 Å long β-helical domain. The N-terminal domain of the IgA protease is found to possess a chymotrypsin-like fold. However, this catalytic domain contains a unique loop D that extends over the active site acting as a lid, gating substrate access. The data presented provide a structural basis for the known ability of IgA proteases to only cleave the P/S/T rich hinge peptide unique to IgA1 in the context of the intact fold of the immunoglobulin. Based upon the structural data as well as molecular modeling, a model is presented that suggests the unique, extended loop D in this IgA protease sterically occludes the active site binding cleft in the absence of immunoglobulin binding. Only in the context of binding of the IgA1 immunoglobulin Fc domain in a valley formed between the N-terminal protease domain and another domain appended to the β-helix spine (domain-2) is the lid stabilized in an open conformation. The stabilization of this open conformation through Fc association subsequently allows access of the hinge peptide to the active site resulting in recognition and cleavage of the substrate.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
14.9
作者：
Comeau, SR;Gatchell, DW;Camacho, CJ
通讯作者：
Camacho, CJ
影响因子：
3.5
作者：
Beck, SC;Meyer, TF
通讯作者：
Meyer, TF
影响因子：
3.1
作者：
Chintalacharuvu, KR;Chuang, PD;Morrison, SL
通讯作者：
Morrison, SL
DOI：
10.1107/s0907444903021784
发表时间：
2003-12-01
影响因子：
2.2
作者：
Holyoak, T;Fenn, TD;Petsko, GA
通讯作者：
Petsko, GA