THE LYSOSTAPHIN ENDOPEPTIDASE RESISTANCE GENE (EPR) SPECIFIES MODIFICATION OF PEPTIDOGLYCAN CROSS-BRIDGES IN STAPHYLOCOCCUS SIMULANS AND STAPHYLOCOCCUS-AUREUS
THE LYSOSTAPHIN ENDOPEPTIDASE RESISTANCE GENE (EPR) SPECIFIES MODIFICATION OF PEPTIDOGLYCAN CROSS-BRIDGES IN STAPHYLOCOCCUS SIMULANS AND STAPHYLOCOCCUS-AUREUS
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DOI：
10.1128/aem.61.4.1475-1479.1995
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发表时间：
1995-04-01
影响因子：
4.4
通讯作者：
SLOAN, GL
中科院分区：
文献类型：
--
作者：
DEHART, HP;HEATH, HE;SLOAN, GL
模拟葡萄球菌生物变种溶葡萄球菌产生一种胞外甘氨酰甘氨酸内肽酶（溶葡萄球菌酶），通过水解其他葡萄球菌细胞壁肽聚糖中的交叉桥来裂解其他葡萄球菌。内肽酶（end）和内肽酶抗性（epr）基因位于质粒pACK1上。将含有末端的8.4kb片段克隆到穿梭载体pLI50中，然后导入金黄色葡萄球菌RN4220中。重组S.金黄色葡萄球菌细胞产生内肽酶，并且对酶的裂解具有抗性，这表明克隆的片段也含有EPR。去除附属壁聚合物（蛋白质、磷壁酸和脂磷壁酸）的处理并没有改变S. simulans biovar staphylolyticus或S.各种壁组分的免疫学分析表明，存在与内肽酶抗性相关的表位，并且这些表位仅在两个物种的epr（+）菌株的肽聚糖上发现。用内肽酶处理纯化的肽聚糖证实，两个物种的抗性或易感性是肽聚糖本身的性质。比较这些肽聚糖的化学组成，发现epr（+）细胞中的交叉桥比没有epr的细胞含有更多的丝氨酸和更少的甘氨酸残基。来自pACK1的8.4 kb片段的存在也增加了两个物种对甲氧西林的敏感性。
Staphylococcus simulans biovar staphylolyticus produces an extracellular glycylglycine endopeptidase (lysostaphin) that lyses other staphylococci by hydrolyzing the cross bridges in their cell wall peptidoglycans. The genes for endopeptidase (end) and endopeptidase resistance (epr) reside on plasmid pACK1. An 8.4-kb fragment containing end was cloned into shuttle vector pLI50 and was then introduced into Staphylococcus aureus RN4220. The recombinant S. aureus cells produced endopeptidase and were resistant to lysis by the enzyme, which indicated that the cloned fragment also contained epr. Treatments to remove accessory wall polymers (proteins, teichoic acids, and lipoteichoic acids) did not change the endopeptidase sensitivity of walls from strains of S. simulans biovar staphylolyticus or of S. aureus with and without epr, Immunological analyses of various wall fractions showed that there were epitopes associated with endopeptidase resistance and that these epitopes were found only on the peptidoglycans of epr(+) strains of both species, Treatment of purified peptidoglycans with endopeptidase confirmed that resistance or susceptibility of both species was a property of the peptidoglycan itself. A comparison of the chemical compositions of these peptidoglycans revealed that cross bridges in the epr(+) cells contained more serine and fewer glycine residues than those of cells without epr. The presence of the 8.4-kb fragment from pACK1 also increased the susceptibility of both species to methicillin.