Sugai M, Fujiwara T, Komatsuzawa H
Department of Microbiology, Hiroshima University School of Dentistry, Hiroshima 734-8553,
Gene. 1998 Dec 11;224(1-2):67-75. doi: 10.1016/s0378-1119(98)00508-3.
Certain Staphylococci possess a gene called epr or lif that renders the cells resistant to lysis by glycylglycine endopeptidase. The resistance is conferred by modifying the amino acid composition of interpeptide chains in cell-wall peptidoglycan by increasing serine content and decreasing glycine content. A gene homologous to epr/lif was cloned from S. aureus RN450 genomic libraries and designated eprh. eprh was found to localize 27bp downstream of a novel cell-wall hydrolase gene lytN, which is in the same orientation with eprh. By analogy with epr/lif, eprh is suggested to be involved in the transfer of certain amino acids, possibly serine or amino acids other than glycine, to interpeptide chains of cell-wall peptidoglycan. Unlike epr/lif, overexpression of eprh in S. aureus did not result in an increased resistance to lysostaphin. Insertional inactivation of eprh or lytN by Campbell-type integration did not affect the susceptibility of the cells to lysostaphin, either. These results suggest that eprh and lytN are not essential genes for S. aureus growth. The physiological function of eprh remains unknown.
某些葡萄球菌拥有一种名为epr或lif的基因，该基因可使细胞对甘氨酰甘氨酸内肽酶的裂解产生抗性。这种抗性是通过增加丝氨酸含量和降低甘氨酸含量来改变细胞壁肽聚糖中肽间链的氨基酸组成而赋予的。从金黄色葡萄球菌RN450基因组文库中克隆到一个与epr/lif同源的基因，并将其命名为epr h。发现epr h位于一个新的细胞壁水解酶基因lyt N下游27bp处，且与epr h方向相同。根据与epr/lif的类比，推测epr h参与了某些氨基酸（可能是丝氨酸或甘氨酸以外的氨基酸）向细胞壁肽聚糖肽间链的转移。与epr/lif不同，在金黄色葡萄球菌中过表达epr h并未导致对溶葡萄球菌素的抗性增加。通过Campbell型整合对epr h或lyt N进行插入失活也未影响细胞对溶葡萄球菌素的敏感性。这些结果表明，epr h和lyt N不是金黄色葡萄球菌生长所必需的基因。epr h的生理功能仍然未知。
