Production of low-affinity forms of penicillin-binding proteins (PBPs), although essential, is not sufficient to protect pneumococci against the inhibitory action of penicillin. Resistance also requires the newly identified protein MurM which, together with MurN, is involved with the synthesis of short peptide branches in the pneumococcal cell wall. Cells in which murM was inactivated produced cell walls without branches and also completely lost penicillin resistance. To understand these surprising observations a 3D-model of MurM was constructed, which helped to put into structural context several of the biochemical and genetic observations made about this protein.

中文翻译：

---

细胞壁分支，青霉素抗性和MurM蛋白的秘密。

低亲和力形式的青霉素结合蛋白（PBPs）的产生，尽管必不可少，但不足以保护肺炎球菌免受青霉素的抑制作用。耐药还需要新鉴定的蛋白MurM，它与MurN一起参与肺炎球菌细胞壁中短肽分支的合成。murM失活的细胞产生无分支的细胞壁，并且也完全丧失了对青霉素的抵抗力。为了理解这些令人惊讶的发现，构建了MurM的3D模型，这有助于将关于该蛋白质的一些生化和遗传观察纳入结构背景。