The cyclic structure of microcin J25, a 21-residue peptide antibiotic from Escherichia coli
The cyclic structure of microcin J25, a 21-residue peptide antibiotic from Escherichia coli
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DOI：
10.1046/j.1432-1327.1999.00085.x
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发表时间：
1999-02-01
期刊：
影响因子：
--
通讯作者：
Rebuffat, S
中科院分区：
文献类型：
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作者：
Blond, A;Péduzzi, J;Rebuffat, S
微菌素J25（MccJ 25）是肠杆菌科细菌产生的肽类抗生素微菌素群中免疫群Ⅰ的唯一代表。它以非SOS依赖性途径诱导易感细胞中的细菌表达[R. A. Salomon和R. Farias（1992）J. Bacteriol. 174，7428-7435]。MccJ 25是通过反相HPLC从微生物素过量产生的大肠杆菌菌株的生长培养基中纯化至均一的。基于氨基酸组成和绝对构型测定、液体二次离子和电喷雾质谱、广泛的二维NMR、酶促和化学降解研究，MccJ 25的结构被解析为21个残基的肽，环（-瓦尔（1）-Gly-Ile-Gly-Thr-Pro-Ile-Ser-Phe-Tyr-Gly-Gly-Gly-Ala-Gly-His-瓦尔-Pro-Glu-Tyr-Phe（21）-）。虽然MccJ 25对大多数内切蛋白酶表现出高抗性，但嗜热菌蛋白酶在Phe（21）-瓦尔（1）键处发生线性化，并导致单一肽MccJ 25-L。MccJ 25对纽波特沙门氏菌和几种大肠杆菌有较强的抗菌活性。大肠杆菌菌株（最小抑制浓度范围在0.01和0.2 μ g·mL（-1）之间）中，嗜热菌蛋白酶线性化的microcin显示出活性的显著降低，表明环状结构对于MccJ 25生物学性质是必需的。由于MccJ 25是核糖体合成的一个更大的肽前体赋予一个N-末端末端，本研究表明，去除这种延伸和头-尾环化所产生的前肽是唯一的翻译后修饰参与成熟的MccJ 25，出现作为第一个环状microcin。
Microcin J25 (MccJ25) is the single representative of the immunity group I of the microcin group of peptide antibiotics produced by Enterobacteriaceae. It induces bacterial filamentation in susceptible cells in a non-SOS-dependent pathway [R. A. Salomon and R. Farias (1992) J. Bacteriol. 174, 7428-7435]. MccJ25 was purified to homogeneity from the growth medium of a microcin-overproducing Escherichia coli strain by reverse-phase HPLC. Based on amino acid composition and absolute configuration determination, liquid secondary ion and electrospray mass spectrometry, extensive two-dimensional NMR, enzymatic and chemical degradations studies, the structure of MccJ25 was elucidated as a 21-residue peptide, cyclo(-Val(1)-Gly-Ile-Gly-Thr-Pro-Ile-Ser-Phe-Tyr-Gly-Gly-Gly-Ala-Gly-His-Val-Pro-Glu-Tyr-Phe(21)-). Although MccJ25 showed high resistance to most of endoproteases, linearization by thermolysin occurred from cleavage at the Phe(21)-Val(1) bond and led to a single peptide, MccJ25-L. While MccJ25 exhibited remarkable antibiotic activity towards Salmonella newport and several E. coli strains (minimal inhibitory concentrations ranging between 0.01 and 0.2 mu g.mL(-1)), the thermolysin-linearized microcin showed a dramatic decrease of the activity, indicating that the cyclic structure is essential for the MccJ25 biological properties. As MccJ25 is ribosomally synthesized as a larger peptide precursor endowed with an N-terminal extremity, the present study shows that removal of this extension and head-tail cyclization of the resulting propeptide are the only posttranslational modifications involved in the maturation of MccJ25, that appears as the first cyclic microcin.