Structural basis for the substrate selectivity of pancreatic lipases and some related proteins
Structural basis for the substrate selectivity of pancreatic lipases and some related proteins
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DOI：
10.1016/s0304-4157(98)00016-1
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发表时间：
1998-11-10
期刊：
影响因子：
--
通讯作者：
Verger, R
中科院分区：
文献类型：
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作者：
Carrière, F;Withers-Martinez, C;Verger, R
经典的人胰脂肪酶 (HPL)、豚鼠胰脂肪酶相关蛋白 2 (GPLRP2) 和来自大黄蜂毒液的磷脂酶 A1 (DolmI PLA1) 说明了胰脂肪酶基因家族针对不同底物选择性的分子进化中的三个有趣步骤。基于 HPL 和 GPLRP2 嵌合体的已知 3D 结构以及 DolmI PLA1 的建模，我们在此回顾这三种酶的结构特征和动力学特性，以更好地理解它们的结构-功能关系。 HPL 仅对甘油三酯表现出显着的活性，而 GPLRP2 显示出高磷脂酶和半乳脂酶活性以及相当的脂肪酶活性。 GPLRP2 与 HPL 显示出高度的结构同源性，但盖子结构域除外，盖子结构域由 5 个氨基酸残基（迷你盖子）组成，而不是 HPL 中的 23 个。 GPLRP2 中盖子结构域的缺失允许自由进入活性位点并减少对大底物（例如半乳糖脂）的空间位阻。盖结构域在底物选择性中的作用已通过定点诱变以及 HPL 和 GPLRP2 盖结构域的替换进行了研究。在 GPLRP2 中添加大尺寸盖子结构域可通过抑制磷脂酶活性来增加甘油三酯的底物选择性。然而，在具有 GPLRP2 mini-lid 的 HPL 突变体的情况下，不会诱导磷脂酶活性。因此，全长盖子结构域的存在并不是解释 HPL 中缺乏磷脂酶活性的独特结构特征。 GPLRP2 嵌合体的 3D 结构和 DolmI PLA1 模型揭示了与 HPL 中的同源环相比，活性位点周围的表面环（β 5 环、β 9 环、盖结构域）具有更高的亲水/亲脂平衡 (HLB)。这一观察结果为 GPLRP2 和 DolmI PLA1 水解极性脂质（例如磷脂）的能力提供了潜在的解释。总之，β 5 环、β 9 环和盖子结构域在甘油三酯、磷脂和半乳糖脂的底物选择性中发挥重要作用。 (C) 1998 Elsevier Science B.V. 保留所有权利。
The classical human pancreatic lipase (HPL), the guinea pig pancreatic lipase-related protein 2 (GPLRP2) and the phospholipase A1 from hornet venom (DolmI PLA1) illustrate three interesting steps in the molecular evolution of the pancreatic lipase gene family towards different substrate selectivities. Based on the known 3D structures of HPL and a GPLRP2 chimera, as well as the modeling of DolmI PLA1, we review here the structural features and the kinetic properties of these three enzymes for a better understanding of their structure-function relationships. HPL displays significant activity only on triglycerides, whereas GPLRP2 displays high phospholipase and galactolipase activities, together with a comparable lipase activity. GPLRP2 shows high structural homology with HPL with the exception of the lid domain which is made of five amino acid residues (mini-lid) instead of 23 in HPL. The lid domain deletion in GPLRP2 allows the free access to the active site and reduces the steric hindrance towards large substrates, such as galactolipids. The role of the lid domain in substrate selectivity has been investigated by site-directed mutagenesis and the substitution of HPL and GPLRP2 lid domains. The addition of a large-size lid domain in GPLRP2 increases the substrate selectivity for triglycerides by depressing the phospholipase activity. The phospholipase activity is, however, not induced in the case of the HPL mutant with GPLRP2 mini-lid. Therefore, the presence of a full-length lid domain is not the unique structural feature explaining the absence of phospholipase activity in HPL. The 3D structure of the GPLRP2 chimera and the model of DolmI PLA1 reveal a higher hydrophilic/lipophilic balance (HLB) of the surface loops (beta 5 loop, beta 9 loop, lid domain) surrounding the active site, as compared to the homologous loops in HPL. This observation provides a potential explanation for the ability of GPLRP2 and DolmI PLA1 to hydrolyze polar lipids, such as phospholipids. In conclusion, the beta 5 loop, the beta 9 loop, and the lid domain play an essential role in substrate selectivity towards triglycerides, phospholipids and galactolipids. (C) 1998 Elsevier Science B.V. All rights reserved.