Harris Lyle, van Zyl Leonardo J, Kirby-McCullough Bronwyn M, Damelin Leonard H, Tiemessen Caroline T, Trindade Marla
Institute for Microbial Biotechnology and Metagenomics, University of the Western Cape, Cape Town, South Africa.
Centre for HIV & STIs, National Institute of Communicable Diseases, Sandringham, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, South Africa.
Plasmid. 2018 Jun;98:56-62. doi: 10.1016/j.plasmid.2018.09.008. Epub 2018 Sep 18.
The vaginal mucosa is dominated by Gram positive, rod shaped lactobacilli which serve as a natural barrier against infection. In both healthy- and bacterial vaginosis (BV)-infected women Lactobacillus crispatus and Lactobacillus jensenii have been found to be the predominant Lactobacillus species. Many studies have been conducted to assess factors influencing lactobacilli dominance in the vaginal microbiome. In the present study two plasmids, pLc4 and pLc17, isolated from vaginal Lactobacillus strains of both healthy and BV-infected women were characterized. The smaller plasmid, pLc4 (4224 bp), was detected in both L. crispatus and L. jensenii strains, while pLc17 was only detected in L. crispatus. Based on its nucleotide sequence pLc4 appears highly novel, with its replication protein having 44% identity to the replication initiation protein of pSMQ173b_03. Phylogenetic analysis with other Rolling Circle Replication plasmids confirmed that pLc4 shows a low degree of similarity to these plasmids. Plasmid pLc17 (16,663 bp) appears to carry both a RCR replicon and a theta replicon, which is rare in naturally occurring plasmids. pLc4 was maintained at a high copy number of 29, while pLc17 appears to be a medium copy number plasmid maintained at 11 copies per chromosome. While sequence analysis is a valuable tool to study cryptic plasmids, further function-based analysis will be required in order to fully elucidate the role of these plasmids within the vaginal milieu.
阴道黏膜以革兰氏阳性、杆状的乳酸杆菌为主，它们是抵御感染的天然屏障。在健康女性和患有细菌性阴道病（BV）的女性中，卷曲乳酸杆菌和詹氏乳酸杆菌均被发现是主要的乳酸杆菌种类。已经开展了许多研究来评估影响阴道微生物群中乳酸杆菌优势地位的因素。在本研究中，对从健康女性和BV感染女性的阴道乳酸杆菌菌株中分离出的两个质粒pLc4和pLc17进行了表征。较小的质粒pLc4（4224 bp）在卷曲乳酸杆菌和詹氏乳酸杆菌菌株中均被检测到，而pLc17仅在卷曲乳酸杆菌中被检测到。基于其核苷酸序列，pLc4显得非常新颖，其复制蛋白与pSMQ173b_03的复制起始蛋白具有44%的同一性。与其他滚环复制质粒的系统发育分析证实，pLc4与这些质粒的相似性较低。质粒pLc17（16,663 bp）似乎携带一个滚环复制子和一个θ复制子，这在天然质粒中很少见。pLc4以29的高拷贝数维持，而pLc17似乎是一个中等拷贝数的质粒，每条染色体维持11个拷贝。虽然序列分析是研究隐蔽质粒的一种有价值的工具，但为了充分阐明这些质粒在阴道环境中的作用，还需要进一步基于功能的分析。
