Structure and kinetic investigation of Streptococcus pyogenes family GH38 alpha-mannosidase.
Structure and kinetic investigation of Streptococcus pyogenes family GH38 alpha-mannosidase.
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DOI：
10.1371/journal.pone.0009006
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发表时间：
2010-02-03
期刊：
影响因子：
3.7
通讯作者：
Davies GJ
中科院分区：
文献类型：
--
作者：
Suits MD;Zhu Y;Taylor EJ;Walton J;Zechel DL;Gilbert HJ;Davies GJ
α−甘露糖苷酶是由糖苷水解酶(GH)催化的，称为α−甘露糖苷酶。这些酶存在于不同的生长激素序列家族中。大量研究已经探索了更高真核的“GH38”α−甘露糖苷的作用，这些甘露糖苷在杂交N-聚糖的修饰和多样化中发挥关键作用；这些过程与癌症和自身免疫性疾病具有强烈的细胞联系。这些酶中研究最广泛的是果蝇GH38α−甘露糖苷酶II，它被证明是一种保留的α−甘露糖苷酶，它同时针对α−1，3和α−1，6甘露糖基连接，这种活性使该酶能够处理GlcNAc(Man)5(GlcNAc)2杂化N-糖聚糖到GlcNAc(Man)3(GlcNAc)2。人们对许多细菌物种，主要但不是唯一的病原体和共生体，也具有推测的GH38α−甘露糖苷酶的活性和特异性未知的了解要少得多。在这里，我们证明了化脓性链球菌(M1 GAS SF370)GH38酶(Spy1604；以下简称SpGH38)是一种α−甘露糖苷酶，具有α−1，3甘露糖苷键的特异性。SpGH38的3D-X-射线结构是在1.9？分辨率下以天然形式获得的，并在2.6？与抑制剂苦马豆素(KI 18µM)形成络合物，揭示了典型的GH38五区结构，其中催化的“-1”亚基与果蝇酶高度相似，包括催化的锌离子。相比之下，SpGH38的“离开群”亚基与更高的真核细胞的GH38亚基显示出相当大的差异；这些特征有助于它们明显的特异性。虽然这种链球菌GH38α−甘露糖苷酶的体内功能尚不清楚，但它被证明是一种活性于N-糖基的α−甘露糖苷酶。SpGH38位于一个操纵子上，该操纵子还含有GH84己糖苷酶(Spy1600)和另外一个推测的糖苷酶。SpGH38的活性和它的基因组背景一起强烈暗示了在宿主N-或可能的O-多糖的降解中的功能。没有任何经典的信号肽进一步表明SpGH38可能是细胞内的，可能在细胞外宿主多糖被分泌的糖苷酶最初消化后随后的降解中发挥作用。
The enzymatic hydrolysis of α−mannosides is catalyzed by glycoside hydrolases (GH), termed α−mannosidases. These enzymes are found in different GH sequence–based families. Considerable research has probed the role of higher eukaryotic “GH38” α−mannosides that play a key role in the modification and diversification of hybrid N-glycans; processes with strong cellular links to cancer and autoimmune disease. The most extensively studied of these enzymes is the Drosophila GH38 α−mannosidase II, which has been shown to be a retaining α−mannosidase that targets both α−1,3 and α−1,6 mannosyl linkages, an activity that enables the enzyme to process GlcNAc(Man)5(GlcNAc)2 hybrid N-glycans to GlcNAc(Man)3(GlcNAc)2. Far less well understood is the observation that many bacterial species, predominantly but not exclusively pathogens and symbionts, also possess putative GH38 α−mannosidases whose activity and specificity is unknown. Here we show that the Streptococcus pyogenes (M1 GAS SF370) GH38 enzyme (Spy1604; hereafter SpGH38) is an α−mannosidase with specificity for α−1,3 mannosidic linkages. The 3D X-ray structure of SpGH38, obtained in native form at 1.9 Å resolution and in complex with the inhibitor swainsonine (K i 18 µM) at 2.6 Å, reveals a canonical GH38 five-domain structure in which the catalytic “–1” subsite shows high similarity with the Drosophila enzyme, including the catalytic Zn2+ ion. In contrast, the “leaving group” subsites of SpGH38 display considerable differences to the higher eukaryotic GH38s; features that contribute to their apparent specificity. Although the in vivo function of this streptococcal GH38 α−mannosidase remains unknown, it is shown to be an α−mannosidase active on N-glycans. SpGH38 lies on an operon that also contains the GH84 hexosaminidase (Spy1600) and an additional putative glycosidase. The activity of SpGH38, together with its genomic context, strongly hints at a function in the degradation of host N- or possibly O-glycans. The absence of any classical signal peptide further suggests that SpGH38 may be intracellular, perhaps functioning in the subsequent degradation of extracellular host glycans following their initial digestion by secreted glycosidases.
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影响因子：
158.5
作者：
Davies, HD;McGeer, A;Naus, M
通讯作者：
Naus, M
DOI：
10.1107/s0907444905036693
发表时间：
2006-01-01
影响因子：
2.2
作者：
Evans, P
通讯作者：
Evans, P
影响因子：
2.9
作者：
Englebienne, Pablo;Fiaux, Helene;Moitessier, Nicolas
通讯作者：
Moitessier, Nicolas
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：
5.7
作者：
DAVIES, G;HENRISSAT, B
通讯作者：
HENRISSAT, B