Beyond the ABCs—Discovery of Three New Plasmid Types in Rhodobacterales (RepQ, RepY, RepW)

Microorganisms

Jörg Overmann¹  Jörn Petersen¹  Heike M. Freese¹  Victoria Ringel¹ 

[1] Leibniz-Institut DSMZ—Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstraße 7 B, 38124 Braunschweig, Germany;

关键词: cryptic plasmids;    replicase;    plasmid classification;    chromids;    evolution;    phylogenomics;   

DOI  :  10.3390/microorganisms10040738

来源: DOAJ

【 摘 要 】

Copiotrophic marine bacteria of the Roseobacter group (Rhodobacterales, Alphaproteobacteria) are characterized by a multipartite genome organization. We sequenced the genomes of Sulfitobacter indolifex DSM 14862^T and four related plasmid-rich isolates in order to investigate the composition, distribution, and evolution of their extrachromosomal replicons (ECRs). A combination of long-read PacBio and short-read Illumina sequencing was required to establish complete closed genomes that comprised up to twelve ECRs. The ECRs were differentiated in stably evolving chromids and genuine plasmids. Among the chromids, a diagnostic RepABC-8 replicon was detected in four Sulfitobacter species that likely reflects an evolutionary innovation that originated in their common ancestor. Classification of the ECRs showed that the most abundant plasmid system is RepABC, followed by RepA, DnaA-like, and RepB. However, the strains also contained three novel plasmid types that were designated RepQ, RepY, and RepW. We confirmed the functionality of their replicases, investigated the genetic inventory of the mostly cryptic plasmids, and retraced their evolutionary origin. Remarkably, the RepY plasmid of S. pontiacus DSM 110277 is the first high copy-number plasmid discovered in Rhodobacterales.

【 授权许可】

Unknown