Pseudomonas aeruginosa LD-Carboxypeptidase, a Serine Peptidase with a Ser-His-Glu Triad and a Nucleophilic Elbow*
Pseudomonas aeruginosa LD-Carboxypeptidase, a Serine Peptidase with a Ser-His-Glu Triad and a Nucleophilic Elbow*
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铜绿假单胞菌 LD-羧肽酶，一种具有 Ser-His-Glu 三联体和亲核弯头的丝氨酸肽酶*
DOI：
10.1074/jbc.m506328200
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发表时间：
2005
影响因子：
4.8
通讯作者：
M. Bochtler
中科院分区：
文献类型：
--
作者：
H. Korza;M. Bochtler
Id-羧肽酶（EC 3.4.17.13）因其切割在细菌肽聚糖中天然存在的l-和d-氨基酸之间的酰胺键的能力而命名。它们对内消旋-二氨基庚二酸和d-丙氨酸之间的连接具有特异性，因此将GlcNAc-MurNAc四肽降解为相应的三肽。由于只有三肽可以作为肽聚糖的结构单元被重复使用，因此认为ld-carboxypeptidases在肽聚糖的再循环中起作用。尽管肽聚糖生物合成的药物利益，折叠和催化类型的ld-羧肽酶是未知的。在这里，我们表明，以前未表征的开放阅读框架在铜绿假单胞菌具有乳酸脱氢酶羧肽酶活性，并提出这种酶的晶体结构。结构分析表明，该酶由N端β折叠结构域和C端β桶结构域组成。在两个结构域的界面处，Ser 115在链-转角-螺旋基序的背景下采用高度应变的构象，其类似于αβ-水解酶中的“亲核弯头”。丝氨酸115与组氨酸残基氢键结合，组氨酸残基由谷氨酸残基定向。在氨基酸序列中以Ser-Glu-His顺序出现的所有三个残基在天然存在的Id-羧肽酶中是严格保守的，并且不能突变为丙氨酸而不丧失活性。我们得出结论，LD-羧肽酶是丝氨酸肽酶与Ser-His-Glu催化三联体。
ld-Carboxypeptidases (EC 3.4.17.13) are named for their ability to cleave amide bonds between l- and d-amino acids, which occur naturally in bacterial peptidoglycan. They are specific for the link between meso-diaminopimelic acid and d-alanine and therefore degrade GlcNAc-MurNAc tetrapeptides to the corresponding tripeptides. As only the tripeptides can be reused as peptidoglycan building blocks, ld-carboxypeptidases are thought to play a role in peptidoglycan recycling. Despite the pharmaceutical interest in peptidoglycan biosynthesis, the fold and catalytic type of ld-carboxypeptidases are unknown. Here, we show that a previously uncharacterized open reading frame in Pseudomonas aeruginosa has ld-carboxypeptidase activity and present the crystal structure of this enzyme. The structure shows that the enzyme consists of an N-terminal β-sheet and a C-terminal β-barrel domain. At the interface of the two domains, Ser115 adopts a highly strained conformation in the context of a strand-turn-helix motif that is similar to the “nucleophilic elbow” in αβ-hydrolases. Ser115 is hydrogen-bonded to a histidine residue, which is oriented by a glutamate residue. All three residues, which occur in the order Ser-Glu-His in the amino acid sequence, are strictly conserved in naturally occurring ld-carboxypeptidases and cannot be mutated to alanines without loss of activity. We conclude that ld-carboxypeptidases are serine peptidases with Ser-His-Glu catalytic triads.
DOI：
10.1111/j.1432-1033.1995.0788h.x
发表时间：
1995-06
期刊：
European journal of biochemistry
影响因子：
--
作者：
N. Budisa;Boris Steipe;P. Demange;C. Eckerskorn;J. Kellermann;R. Huber
通讯作者：
N. Budisa;Boris Steipe;P. Demange;C. Eckerskorn;J. Kellermann;R. Huber