X-ray structure of ILL2, an auxin-conjugate amidohydrolase from Arabidopsis thaliana.
X-ray structure of ILL2, an auxin-conjugate amidohydrolase from Arabidopsis thaliana.
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DOI：
10.1002/prot.22124
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发表时间：
2009-01
影响因子：
2.9
通讯作者：
Phillips, George N., Jr.
中科院分区：
文献类型：
--
作者：
Bitto, Eduard;Bingman, Craig A.;Bittova, Lenka;Houston, Norma L.;Boston, Rebecca S.;Fox, Brian G.;Phillips, George N., Jr.
植物激素吲哚-3-乙酸（IAA）是最丰富的天然生长素，参与植物发育和生长的许多方面。植物中的IAA水平由来自肽酶M20 D家族的一组特定的酰胺水解酶调节，所述酰胺水解酶从其结合的储存形式释放活性激素。在这里，我们描述的IAA-氨基酸水解酶IAA-leucine resistant-like gene 2（ILL 2）从拟南芥在2.0 nm分辨率的X-射线晶体结构。ILL 2优先水解生长素-氨基酸缀合物N-（吲哚-3-乙酰基）-丙氨酸。ILL 2的总体结构让人想起来自M20肽酶家族的双核金属肽酶。该结构由两个结构域组成，较大的催化结构域具有3层αβα三明治结构和氨肽酶拓扑结构，较小的卫星结构域具有2层αβ三明治结构和α-β辫状拓扑结构。ILL 2活性位点中的金属配位残基包括一个保守的半胱氨酸，该半胱氨酸清楚地将该蛋白质与先前结构表征的M20肽酶家族成员区分开来。N-（吲哚-3-乙酰基）-丙氨酸到ILL 2的活性位点的建模表明，Leu 175作为该酶的氨基酸侧链特异性的关键决定因素。此外，催化双金属中心附近的疏水口袋可能识别底物的吲哚基部分。最后，ILL 2的活性位点含有一个绝对保守的谷氨酸（Glu 172），它被很好地定位为一般的酸碱残基。总的来说，ILL 2的结构表明该酶可能使用遵循为M20肽酶家族的其他酶建立的范例的催化机制。
The plant hormone indole-3-acetic acid (IAA) is the most abundant natural auxin involved in many aspects of plant development and growth. The IAA levels in plants are modulated by a specific group of amidohydrolases from the peptidase M20D family that release the active hormone from its conjugated storage forms. Here we describe the X-ray crystal structure of IAA-amino acid hydrolase IAA-leucine resistant-like gene 2 (ILL2) from Arabidopsis thaliana at 2.0 Å resolution. ILL2 preferentially hydrolyses the auxin-amino acid conjugate N-(indol-3-acetyl)-alanine. The overall structure of ILL2 is reminiscent of dinuclear metallopeptidases from the M20 peptidase family. The structure consists of two domains, a larger catalytic domain with 3-layer αβα sandwich architecture and aminopeptidase topology and a smaller satellite domain with 2-layer αβ sandwich architecture and alpha-beta plaits topology. The metal coordinating residues in the active site of ILL2 include a conserved cysteine that clearly distinguishes this protein from previously structurally characterized members of the M20 peptidase family. Modeling of N-(indol-3-acetyl)-alanine into the active site of ILL2 suggests that Leu175 serves as a key determinant for the amino acid side chain specificity of this enzyme. Furthermore, a hydrophobic pocket nearby the catalytic dimetal center likely recognizes the indolyl moiety of the substrate. Finally, the active site of ILL2 harbors an absolutely conserved glutamate (Glu172), which is well positioned to act as a general acid-base residue. Overall, the structure of ILL2 suggests that this enzyme likely uses a catalytic mechanism that follows the paradigm established for the other enzymes of the M20 peptidase family.
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影响因子：
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作者：
Campanella, JJ;Larko, D;Smalley, J
通讯作者：
Smalley, J
影响因子：
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作者：
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DOI：
10.1073/pnas.77.7.3875
发表时间：
1980-01-01
期刊：
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影响因子：
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作者：
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通讯作者：
LIPSCOMB, WN
影响因子：
2.9
作者：
MADEJ, T;GIBRAT, JF;BRYANT, SH
通讯作者：
BRYANT, SH
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