Lin C F, Fung Z F, Wu C L, Chung T C
Department of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan, Republic of China.
Plasmid. 1996 Sep;36(2):116-24. doi: 10.1006/plas.1996.0039.
Lactobacillus reuteri G4 contains a 7.0-kb plasmid (pTC82) encoding resistance to chloramphenicol (Cm). Determination of the nucleotide sequence of the genetic determinant (cat-TC) encoding resistance to Cm on pTC82 revealed an open reading frame for a 238-amino-acid Cm acetyltransferase (CAT) monomer. This structural cat gene, 714 bp in length, was highly related (ca. 95% nucleotide and ca. 81% amino acid identity) to the 648-bp cat gene from Staphylococcus aureus plasmid pC194. A total of 6 bp transversions and 4 bp deletions was observed along the whole DNA sequence of cat-TC compared to that of cat-pC194. To determine the activity of the putative cat-TC gene, recombinant plasmid pUC8217 containing the cat determinant from pTC82 was subjected to a maxicell analysis. The observed molecular mass of the synthesized protein, based on electrophoretic mobility, was in reasonable agreement with the 27.3 kDa predicted from the DNA sequence. This is the first reported nucleotide sequence of a Cm-resistance determinant from L. reuteri and also the first evidence of adding Lactobacillus to the list of versatile bacterial genera which naturally acquire the cat-pC194 gene in the microbial ecological system.
罗伊氏乳杆菌G4含有一个7.0 kb的质粒（pTC82），该质粒编码对氯霉素（Cm）的抗性。对pTC82上编码对Cm抗性的遗传决定因子（cat-TC）的核苷酸序列进行测定，发现了一个编码238个氨基酸的Cm乙酰转移酶（CAT）单体的开放阅读框。这个长度为714 bp的结构型cat基因与金黄色葡萄球菌质粒pC194的648 bp cat基因高度相关（核苷酸同一性约为95%，氨基酸同一性约为81%）。与cat-pC194相比，在cat-TC的整个DNA序列中总共观察到6个碱基的颠换和4个碱基的缺失。为了确定推定的cat-TC基因的活性，对含有来自pTC82的cat决定因子的重组质粒pUC8217进行了大细胞分析。根据电泳迁移率观察到的合成蛋白质的分子量与从DNA序列预测的27.3 kDa合理一致。这是首次报道的来自罗伊氏乳杆菌的Cm抗性决定因子的核苷酸序列，也是将乳杆菌添加到在微生物生态系统中自然获得cat-pC194基因的多种细菌属名单中的第一个证据。
