The Genome of Erysipelothrix rhusiopathiae, the Causative Agent of Swine Erysipelas, Reveals New Insights into the Evolution of Firmicutes and the Organism's Intracellular Adaptations

Abstract

Erysipelothrix rhusiopathiae is a Gram-positive bacterium that represents a new class, Erysipelotrichia, in the phylum Firmicutes. The organism is a facultative intracellular pathogen that causes swine erysipelas, as well as a variety of diseases in many animals. Here, we report the first complete genome sequence analysis of a member of the class Erysipelotrichia. The E. rhusiopathiae genome (1,787,941 bp) is one of the smallest genomes in the phylum Firmicutes. Phylogenetic analyses based on the 16S rRNA gene and 31 universal protein families suggest that E. rhusiopathiae is phylogenetically close to Mollicutes, which comprises Mycoplasma species. Genome analyses show that the overall features of the E. rhusiopathiae genome are similar to those of other Gram-positive bacteria; it possesses a complete set of peptidoglycan biosynthesis genes, two-component regulatory systems, and various cell wall-associated virulence factors, including a capsule and adhesins. However, it lacks many orthologous genes for the biosynthesis of wall teichoic acids (WTA) and lipoteichoic acids (LTA) and the dltABCD operon, which is responsible for D-alanine incorporation into WTA and LTA, suggesting that the organism has an atypical cell wall. In addition, like Mollicutes, its genome shows a complete loss of fatty acid biosynthesis pathways and lacks the genes for the biosynthesis of many amino acids, cofactors, and vitamins, indicating reductive genome evolution. The genome encodes nine antioxidant factors and nine phospholipases, which facilitate intracellular survival in phagocytes. Thus, the E. rhusiopathiae genome represents evolutionary traits of both Firmicutes and Mollicutes and provides new insights into its evolutionary adaptations for intracellular survival.

Capsular Polysaccharide of Erysipelothrix rhusiopathiae, the Causative Agent of Swine Erysipelas, and Its Modification with Phosphorylcholine

“…Recently, we sequenced the genome of E. rhusiopathiae and reported that E. rhusiopathiae is phylogenetically related to Mollicutes (Mycoplasma species) (17). Based on genomic phylogenetic trees, we proposed that E. rhusiopathiae and other Erysipelotrichia strains may be separate from Firmicutes and classified as a distinct phylum (17).…”

Characterization and Identification of a Novel Candidate Vaccine Protein through Systematic Analysis of Extracellular Proteins of Erysipelothrix rhusiopathiae

“…ACLK 00000000.2), was obtained from the National Center for Biotechnology Information (NCBI) database (http://www.ncbi.nlm.nih.gov/genomes /MICROBES/microbial_taxtree.html) and compared to the sequence of Fujisawa (accession no. AP012027) (2). ATCC 19414 strain-specific coding sequences (CDS) with a putative choline-binding domain (the GW module) at the C terminus were identified.…”

“…E. rhusiopathiae has been referred to as the "walled relative" of mycoplasma (1), and E. rhusiopathiae is phylogenetically close to Mollicutes (a class that includes the genus Mycoplasma); the genomic features of this organism represent evolutionary traits of both Firmicutes and Mollicutes (2,3).…”

“…E. rhusio-pathiae lacks many orthologous genes for the biosynthesis of wall teichoic acids (WTA) and LTA, as well as the dltABCD operon, which is responsible for the incorporation of D-alanine into WTA and LTA (2). Furthermore, recent analysis of the capsular polysaccharide of E. rhusiopathiae indicated that this bacterium indeed has a complex, heterogeneous capsule that is modified by phosphocholine (22).…”

“…The E. rhusiopathiae strain Fujisawa possesses at least 24 surface proteins that contain either an LPXTG motif or a GW repeat (2). Protective antigens are present in E. rhusiopathiae culture supernatants (23)(24)(25)(26)(27); however, the nature of these protective antigens is entirely unknown.…”