Bouloc P, Jaffé A, D'Ari R
Institut Jacques Monod, Centre National de la Recherche Scientifique, Université Paris, France.
EMBO J. 1989 Jan;8(1):317-23. doi: 10.1002/j.1460-2075.1989.tb03379.x.
Mecillinam, a beta-lactam antibiotic which binds specifically to penicillin-binding protein 2 (PBP2), blocks lateral cell-wall elongation, induces spherical morphology and ultimately kills bacteria. We describe here a new mecillinam-resistant mutant of Escherichia coli, the lov mutant. It possesses active PBP2, as evidenced by its rod shape in the absence of mecillinam (but not in its presence), its ability to filament when septation is inhibited, and its penicillin-binding ability. The lov mutant grows slowly but seems to regulate its macromolecular parameters properly: cell volume, RNA content (ribosome concentration), and DNA content are appropriate for the growth rate, and the growth yield is identical to that of wild type. The lov mutation is located at 41 min on the E.coli genetic map and is recessive. Certain rpsL (StrR) mutations suppress the lov mutant's mecillinam resistance. The allele specificity of the suppression suggests that the lov gene product may interact directly with the ribosomes. The lov gene product thus seems to define a link between PBP2 (the mecillinam target) and the ribosomes; we propose that this link is involved in transmitting information on the growth rate (ribosome concentration) to the peptidoglycan synthesizing apparatus.
美西林是一种β-内酰胺类抗生素，它特异性地结合青霉素结合蛋白2（PBP2），阻止细胞壁侧向延伸，诱导形成球形形态并最终杀死细菌。我们在此描述了一种新的大肠杆菌美西林耐药突变体，即lov突变体。它具有活性PBP2，这可由以下几点证明：在不存在美西林时（但存在美西林时则不然）其呈杆状形态，在隔膜形成受到抑制时具有形成丝状体的能力，以及其青霉素结合能力。lov突变体生长缓慢，但似乎能正常调节其大分子参数：细胞体积、RNA含量（核糖体浓度）和DNA含量与生长速率相适应，且生长产量与野生型相同。lov突变位于大肠杆菌遗传图谱的41分钟处，并且是隐性的。某些rpsL（StrR）突变可抑制lov突变体的美西林耐药性。这种抑制的等位基因特异性表明lov基因产物可能直接与核糖体相互作用。因此，lov基因产物似乎定义了PBP2（美西林作用靶点）与核糖体之间的一种联系；我们提出这种联系参与将生长速率信息（核糖体浓度）传递给肽聚糖合成装置。
