Characterization of a chromosomally encoded glycylglycine endopeptidase of Staphylococcus aureus
Characterization of a chromosomally encoded glycylglycine endopeptidase of Staphylococcus aureus
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DOI：
10.1099/13500872-145-4-801
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发表时间：
1999-04-01
期刊：
影响因子：
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通讯作者：
Jayaswal, RK
中科院分区：
文献类型：
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作者：
Ramadurai, L;Lockwood, KJ;Jayaswal, RK
作者先前报道了从金黄色葡萄球菌的自溶缺陷突变体中克隆了一个裂解酶编码基因lytM。在本工作中，lytM基因在大肠杆菌中过表达，并通过亲和层析和HPLC将产物纯化至均一。LytM切割的肽聚糖片段的生化分析表明LytM是甘氨酰甘氨酸内肽酶。用抗LytM兔IgG的免疫电镜研究表明，LytM在早期指数期表达，并且与亲本菌株相比，在自溶缺陷突变体中过表达。此外，金颗粒在活跃生长的细菌细胞表面上的均匀分布表明LytM在细胞生长中起作用。北方印迹分析的lytM表达的两个全球性的调控突变体，agr和sar，表明lytM的表达增加约两倍，在这些突变体相比，父母。蛋白质同源性搜索显示LytM可能是锌蛋白酶家族的成员，因为它含有同源的38个氨基酸基序Tyr-X-His-X 11-Val-X-12/20-Gly-X 5 -6-His。LytM的原子吸收光谱分析显示存在0.9 mol锌（mol LytM）（-1）。
The authors previously reported the cloning of a lytic-enzyme-encoding gene, lytM, from an autolysis-defective mutant of Staphylococcus aureus. In the present work, the lytM gene was overexpressed in Escherichia coli and the product was purified to homogeneity by affinity chromatography and HPLC. Biochemical analysis of LytM-cleaved peptidoglycan fragments indicated that LytM is a glycylglycine endopeptidase. Immunoelectron microscopic studies with anti-LytM rabbit IgG showed that LytM is expressed during the early exponential phase and is overexpressed in an autolysis-defective mutant compared with the parent strain. Also, a uniform distribution of gold particles on the surface of actively growing bacterial cells indicates that LytM plays a role in cell growth. Northern blot analyses of lytM expression in two global regulatory mutants, agr and sar, showed that expression of lytM is increased about twofold in these mutants as compared with the parents. Protein homology searches revealed that LytM could be a member of the zinc protease family, as it contained a homologous 38-amino-acid motif, Tyr-X-His-X11-Val-X-12/20-Gly-X5-6-His. Atomic absorption spectrometric analysis of LytM revealed the presence of 0.9 mol zinc (mol LytM)(-1) .