Membrane-bound lytic endotransglycosylase in Escherichia coli
Membrane-bound lytic endotransglycosylase in Escherichia coli
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DOI：
10.1128/jb.180.13.3441-3447.1998
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发表时间：
1998-07-01
影响因子：
3.2
通讯作者：
Höltje, JV
中科院分区：
文献类型：
--
作者：
Kraft, AR;Templin, MF;Höltje, JV
新型内型膜结合溶解性转糖基酶emtA的基因定位于E. coli染色体。EmtA是一种表观分子量为22 kDa的脂蛋白。过表达的emtA基因并没有导致在体内溶菌，但酶被证明水解聚糖链分离的胞壁蛋白酰胺酶处理。四糖和六糖的形成，但没有二糖，反映了酶的内特异性。产物的特征在于存在1，6-脱水胞壁酸，表明裂解转糖基酶反应机制。EmtA可以用作将由胞壁素合成机制产生的新生胞壁素链修剪成适当大小的格式化酶，或者它可以参与形成胞壁素球囊中严格控制的小孔，以促进大体积化合物穿过胞壁素屏障的输出。
The gene for a novel endotype membrane-bound lytic transglycosylase, emtA, was mapped at 26.7 min of the E. coli chromosome. EmtA is a lipoprotein with an apparent molecular mass of 22 kDa. Overexpression of the emtA gene did not result in bacteriolysis in vivo, but the enzyme was shown to hydrolyze glycan strands isolated from murein by amidase treatment. The formation of tetra- and hexasaccharides, but no disaccharides, reflects the endospecificity of the enzyme. The products are characterized by the presence of 1,6-anhydromuramic acid, indicating a lytic transglycosylase reaction mechanism, EmtA may function as a formatting enzyme that trims the nascent murein strands produced by the murein synthesis machinery into proper sizes, or it may be involved in the formation of tightly controlled minor holes in the murein sacculus to facilitate the export of bulky compounds across the murein barrier.