Håvarstein L S, Holo H, Nes I F
Laboratory of Microbial Gene Technology, Agricultural University of Norway, As.
Microbiology (Reading). 1994 Sep;140 ( Pt 9):2383-9. doi: 10.1099/13500872-140-9-2383.
Colicin V is a ribosomally synthesized antimicrobial peptide produced by Escherichia coli. Four recently characterized genes, arranged in two convergent operons on the plasmid pCoIV-K30, are required for colicin V synthesis, export and immunity. We report the purification and N-terminal amino acid sequencing of the colicin V protein. Our results demonstrate that the colicin V primary translation product, which consists of 103 amino acids, is proteolytically processed. A leader peptide, consisting of 15 amino acid residues, is removed from the N-terminus during maturation of colicin V. This leader peptide is not related to the N-terminal signal sequences which direct proteins across the cytoplasmic membrane via the Sec pathway. The molecular mass of colicin V, obtained by mass spectrometry analysis, showed that the peptide consists of only unmodified amino acids. The deduced amino acid sequence of the leader peptide was highly homologous to the N-terminal extensions found in non-lantibiotic, peptide bacteriocins produced by Gram-positive bacteria. These findings strongly indicate that colicin V belongs to a family of small peptide bacteriocins that have been found previously only among the Gram-positive lactic acid bacteria.
大肠杆菌素V是由大肠杆菌产生的一种核糖体合成的抗菌肽。在质粒pCoIV-K30上，由两个反向操纵子排列的四个最近鉴定出的基因，是大肠杆菌素V合成、输出和免疫所必需的。我们报道了大肠杆菌素V蛋白的纯化及N端氨基酸测序。我们的结果表明，由103个氨基酸组成的大肠杆菌素V初级翻译产物经过了蛋白水解加工。在大肠杆菌素V成熟过程中，一个由15个氨基酸残基组成的前导肽从N端被切除。这个前导肽与通过Sec途径引导蛋白质穿过细胞质膜的N端信号序列无关。通过质谱分析得到的大肠杆菌素V的分子量表明，该肽仅由未修饰的氨基酸组成。前导肽的推导氨基酸序列与革兰氏阳性菌产生的非羊毛硫抗生素肽类细菌素中发现的N端延伸高度同源。这些发现有力地表明，大肠杆菌素V属于一个小肽类细菌素家族，此前仅在革兰氏阳性乳酸菌中发现过。
