Iwata M
Yakult Central Institute for Microbiological Research, Tokyo, Japan.
Biochimie. 1988 Apr;70(4):553-8. doi: 10.1016/0300-9084(88)90092-2.
Streptococcal plasmid pAM beta 1 was conjugally transferred from Streptococcus lactis KB953 (a transformant of pAM beta 1) into Lactobacillus casei 239. A unique transconjugant, L. casei C2, was found to contain a small (11.1 kilobase pair) plasmid, pLY201, which was derived by a deletion event from pAM beta 1. Restriction analysis revealed that pLY201 was missing approximately 58% of the original pAM beta 1 genome, and contained 5 single restriction sites for AvaI, EcoRI, PvuII, HpaI and KpnI. Physical analyses revealed that the stability and copy number of pLY201 were elevated compared with those of pAM beta 1 in L. casei. In addition, pLY201 was no longer transferable by conjugation.
链球菌质粒pAM beta 1通过接合作用从乳酸链球菌KB953（pAM beta 1的转化体）转移至干酪乳杆菌239。发现一种独特的接合子，即干酪乳杆菌C2，含有一个小的（11.1千碱基对）质粒pLY201，它是由pAM beta 1通过缺失事件衍生而来。限制性分析表明，pLY201缺失了原始pAM beta 1基因组约58%的序列，并含有AvaI、EcoRI、PvuII、HpaI和KpnI的5个单一切割位点。物理分析表明，与干酪乳杆菌中的pAM beta 1相比，pLY201的稳定性和拷贝数有所提高。此外，pLY201不再能通过接合作用进行转移。
