ANALYSIS OF MUREIN AND MUREIN PRECURSORS DURING ANTIBIOTIC-INDUCED LYSIS OF ESCHERICHIA-COLI
ANALYSIS OF MUREIN AND MUREIN PRECURSORS DURING ANTIBIOTIC-INDUCED LYSIS OF ESCHERICHIA-COLI
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DOI：
10.1128/jb.173.11.3425-3431.1991
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发表时间：
1991-06-01
影响因子：
3.2
通讯作者：
HOLTJE, JV
中科院分区：
文献类型：
--
作者：
KOHLRAUSCH, U;HOLTJE, JV
通过对麦尿素代谢的研究，监测了D-环丝氨酸、莫诺霉素或青霉素G诱导的大肠杆菌裂解情况。可溶性粘蛋白前体UDP-N-acetylmuramyl-L-alanyl-D-glutamyl-m-diaminopimelyl-D-alanyl-D-alanine(UDP-MurNAc-五肽)和载体连接的MurNAc-(pentapeptide)-pyrophosphoryl-undecaprenol以及N-acetylglucosamine-beta-1，4-MurNAc-(pentapeptide)-pyrophosphoryl-undecaprenol的水平有特定的变化。在青霉素的存在下，尽管UDP-MurNAc-五肽的水平保持正常，但在青霉素的存在下，脂联前体的浓度在溶解开始之前意外地下降。在莫诺霉素的情况下，它特异性地阻止了毛霉素多糖链的形成，脂质连接的前体以及UDP-MurNAc-五肽如预期的那样积累。D-环丝氨酸抑制UDP-MurNAc-五肽的生物合成，从而导致所有三种前体的减少。Murein的肌肽组成表现出一般性的变化，如两个相邻的中二氨基甲酸残基之间不寻常的DL-交叉桥的增加，以及由于不受控制的DL-和DD-羧肽酶活性的结果，三肽增加，四肽和五肽减少。糖链的平均长度减少。当糖链按长度分级时，不仅在存在青霉素的情况下，而且在存在莫诺霉素的情况下，观察到单双糖单位的数量显著增加。这一结果是由胞外胞壁酰胺酶的作用解释的，例如大肠杆菌中存在的裂解转糖基酶。有人认为，抗生素诱导的细菌溶解是局部限制在细胞赤道区的外胞壁酰胺酶拉链状裂解毛尿素网的结果。
Lysis of Escherichia coli induced by either D-cycloserine, moenomycin, or penicillin G was monitored by studying murein metabolism. The levels of the soluble murein precursor UDP-N-acetylmuramyl-L-alanyl-D-glutamyl-m-diaminopimelyl-D-alanyl-D-alanine (UDP-MurNAc-pentapeptide) and the carrier-linked MurNAc-(pentapeptide)-pyrophosphoryl-undecaprenol as well as N-acetylglucosamine-beta-1,4-MurNAc-(pentapeptide)-pyrophosphoryl-undecaprenol varied in a specific way. In the presence of penicillin, which is known to interfere with the cross-linking of murein, the concentration of the lipid-linked precursors unexpectedly decreased before the onset of lysis, although the level of UDP-MurNAc-pentapeptide remained normal. In the case of moenomycin, which specifically blocks the formation of the murein polysaccharide strands, the lipid-linked precursors as well as UDP-MurNAc-pentapeptide accumulated as was expected. D-Cycloserine, which inhibits the biosynthesis of UDP-MurNAc-pentapeptide, consequently caused a decrease in all three precursors. The muropeptide composition of the murein showed general changes such as an increase in the unusual DL-cross bridge between two neighboring meso-diaminopimelic acid residues and, as a result of uncontrolled DL- and DD-carboxypeptidase activity, an increase in tripeptidyl and a decrease in tetrapeptidyl and pentapeptidyl moieties. The average length of the glycan strands decreasd. When the glycan strands were fractionated according to length, a dramatic increase in the amount of single disaccharide units was observed not only in the presence of penicillin but also in the presence of moenomycin. This result is explained by the action of an exo-muramidase, such as the lytic transglycosylases present in E. coli. It is proposed that antibiotic-induced bacteriolysis is the result of a zipperlike splitting of the murein net by exo-muramidases locally restricted to the equatorial zone of the cell.