Crystal structure of Saccharomyces cerevisiae glutamine synthetase Gln1 suggests a nanotube-like supramolecular assembly
Crystal structure of Saccharomyces cerevisiae glutamine synthetase Gln1 suggests a nanotube-like supramolecular assembly
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酿酒酵母谷氨酰胺合成酶 Gln1 的晶体结构表明纳米管状超分子组装体
DOI：
10.1002/prot.22403
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发表时间：
2009-07-01
影响因子：
2.9
通讯作者：
Zhou, Cong-Zhao
中科院分区：
文献类型：
--
作者：
He, Yong-Xing;Gui, Long;Zhou, Cong-Zhao
谷氨酰胺合成酶(GS，EC 6.3.1.2)是一种酶，催化谷氨酸和铵的缩合形成谷氨酰胺，并伴随着ATP的水解。1有三种不同类别的GS酶，称为GSI、GSII和GSIII。GSI酶是原核生物所特有的，形成12个相同亚基的寡聚体。2 GSI酶的活性受酪氨酸残基的腺化作用调节。3GSII酶存在于真核生物和一些细菌中(根瘤科、弗兰克科和链霉菌科，它们也有GSI)。它们形成相同亚基的分组体。4在哺乳动物中，GSII酶消除游离氨，并将兴奋性毒性谷氨酸转化为谷氨酰胺，而谷氨酰胺不具有神经毒性。在植物中，有两种或两种以上的GSII同工酶，由于它们在氨同化过程中的作用，它们是一些除草剂的靶标。GSIII酶首先在脆弱类杆菌中被发现，随后在更多的厌氧细菌和蓝藻中被鉴定。6-8它们是相同亚基的六聚体，比GSI(450-470个残基)或GSII(350-420个残基)大得多(约700个残基)。9.
Glutamine synthetase (GS, EC 6.3. 1.2) is an enzyme that catalyzes the condensation of glutamate and ammonium to form glutamine, with concomitant hydrolysis of ATP. 1 There are three different classes of GS enzymes, referred to as GSI, GSII, and GSIII. GSI enzymes are specific to prokaryotes and form oligomers of 12 identical subunits. 2 The activity of GSI enzyme is regulated by the adenylation of a tyrosine residue. 3 GSII enzymes are found in eukaryotes and some bacteria (Rhizobiaceae, Frankiaceae, and Streptomycetaceae families, which also have GSI). They form decamers of identical subunits. 4 In mammals, GSII enzymes eliminate free ammonia and convert the excitotoxic glutamate into glutamine, which is not neurotoxic. 5 In plants, there are two or more isoenzymes of GSII, which are targets of some herbicides because of their roles in ammonia assimilation. GSIII enzymes were first found in Bacteroides fragilis and identified afterward in a few more anaerobic bacteria and cyanobacteria. 6–8 They are hexamers of identical subunits which are much larger (about 700 residues) than that of GSI (450–470 residues) or GSII (350–420 residues) enzymes. 9