{"title":"The extrachromosomal elements of the Naegleria genus: How little we know","authors":"B.T. Nguyen , N.M. Chapman , S. Tracy , K.M. Drescher","doi":"10.1016/j.plasmid.2021.102567","DOIUrl":null,"url":null,"abstract":"<div><p>There are currently 47 characterized species in the <em>Naegleria</em> genus of free-living amoebae. Each amoeba has thousands of extrachromosomal elements that are closed circular structures comprised of a single ribosomal DNA (rDNA) copy and a large non-rDNA sequence. Despite the presence of putative open reading frames and introns, ribosomal RNA is the only established transcript. A single origin of DNA replication (ori) has been mapped within the non-rDNA sequence for one species (<em>N. gruberi</em>), a finding that strongly indicates that these episomes replicate independently of the cell's chromosomal DNA component. This article reviews that which has been published about these interesting DNA elements and by analyzing available sequence data, discusses the possibility that different phylogenetically related clusters of <em>Naegleria</em> species individually conserve ori structures and suggests where the rRNA promoter and termination sites may be located.</p></div>","PeriodicalId":49689,"journal":{"name":"Plasmid","volume":"115 ","pages":"Article 102567"},"PeriodicalIF":1.8000,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.plasmid.2021.102567","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Plasmid","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0147619X21000147","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GENETICS & HEREDITY","Score":null,"Total":0}
引用次数: 2
Abstract
There are currently 47 characterized species in the Naegleria genus of free-living amoebae. Each amoeba has thousands of extrachromosomal elements that are closed circular structures comprised of a single ribosomal DNA (rDNA) copy and a large non-rDNA sequence. Despite the presence of putative open reading frames and introns, ribosomal RNA is the only established transcript. A single origin of DNA replication (ori) has been mapped within the non-rDNA sequence for one species (N. gruberi), a finding that strongly indicates that these episomes replicate independently of the cell's chromosomal DNA component. This article reviews that which has been published about these interesting DNA elements and by analyzing available sequence data, discusses the possibility that different phylogenetically related clusters of Naegleria species individually conserve ori structures and suggests where the rRNA promoter and termination sites may be located.
期刊介绍：
Plasmid publishes original research on genetic elements in all kingdoms of life with emphasis on maintenance, transmission and evolution of extrachromosomal elements. Objects of interest include plasmids, bacteriophages, mobile genetic elements, organelle DNA, and genomic and pathogenicity islands.
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