Characterization and evolution of cell division and cell wall synthesis genes in the bacterial phyla Verrucomicrobia, Lentisphaerae, Chlamydiae and Planctomycetes and phylogenetic comparison with rRNA genes

摘要

In the past, studies on the relationships of the bacterial phyla Planctomycetes, Chlamydiae, Lentisphaerae, and\ud\udVerrucomicrobia using different phylogenetic markers have been controversial. Investigations based on 16S\ud\udrRNA sequence analyses suggested a relationship of the four phyla, showing the branching order Planctomycetes,\ud\udChlamydiae, Verrucomicrobia/Lentisphaerae. Phylogenetic analyses of 23S rRNA genes in this study also\ud\udsupport a monophyletic grouping and their branching order—this grouping is significant for understanding\ud\udcell division, since the major bacterial cell division protein FtsZ is absent from members of two of the phyla\ud\udChlamydiae and Planctomycetes. In Verrucomicrobia, knowledge about cell division is mainly restricted to the\ud\udrecent report of ftsZ in the closely related genera Prosthecobacter and Verrucomicrobium. In this study, genes of\ud\udthe conserved division and cell wall (dcw) cluster (ddl, ftsQ, ftsA, and ftsZ) were characterized in all verrucomicrobial\ud\udsubdivisions (1 to 4) with cultivable representatives (1 to 4). Sequence analyses and transcriptional\ud\udanalyses in Verrucomicrobia and genome data analyses in Lentisphaerae suggested that cell division is based on\ud\udFtsZ in all verrucomicrobial subdivisions and possibly also in the sister phylum Lentisphaerae. Comprehensive\ud\udsequence analyses of available genome data for representatives of Verrucomicrobia, Lentisphaerae, Chlamydiae,\ud\udand Planctomycetes strongly indicate that their last common ancestor possessed a conserved, ancestral type of\ud\uddcw gene cluster and an FtsZ-based cell division mechanism. This implies that Planctomycetes and Chlamydiae\ud\udmay have shifted independently to a non-FtsZ-based cell division mechanism after their separate branchings\ud\udfrom their last common ancestor with Verrucomicrobia.