Frehel C, Ryter A
J Bacteriol. 1979 Feb;137(2):947-55. doi: 10.1128/jb.137.2.947-955.1979.
The aim of this study was to ascertain whether or not the absence of cell wall growth zones, deduced from the analysis of autoradiographs of DL-[3H]mesodiaminopimelic acid pulse-labeled cells of a Dap- Lys- mutant of Bacillus megaterium, was due to a high peptidoglycan turnover. Turnover was determined in very precise experimental conditions because two kinds of turnover occurred: a low, acid-soluble turnover and a high, acid-insoluble one. The latter was detected during a chase in the culture medium when bacteria were centrifuged before treatment with trichloroacetic acid. Otherwise the acid-insoluble released material precipitated with the bacteria. In the electron microscope this material presented a globular structure and contained both peptidoglycan and teichoic acid. The acid-insoluble turnover was mainly produced by a lytic acitivity that was released into the culture medium. This thermolabile activity was not due to cell lysis. It was implicated in septum cleavage and in the detachment of wall fragments from the cell surface, but did not seem indispensable for cell elongation. The acid-soluble turnover was much weaker and seemed to be indispensable for cell elongation.
本研究的目的是确定，从巨大芽孢杆菌Dap-Lys-突变体的DL-[3H]中-二氨基庚二酸脉冲标记细胞的放射自显影片分析推断出的细胞壁生长区缺失，是否归因于高肽聚糖周转率。由于发生两种周转率，即低的酸溶性周转率和高的酸不溶性周转率，因此在非常精确的实验条件下测定周转率。当细菌在用三氯乙酸处理之前进行离心时，在培养基的追踪过程中检测到后者。否则，酸不溶性释放物质会与细菌一起沉淀。在电子显微镜下，这种物质呈现出球状结构，并且含有肽聚糖和磷壁酸。酸不溶性周转率主要由释放到培养基中的溶菌活性产生。这种热不稳定活性并非由于细胞裂解。它与隔膜裂解以及壁片段从细胞表面的脱离有关，但似乎对于细胞伸长并非必不可少。酸溶性周转率要弱得多，并且似乎对于细胞伸长必不可少。
