title: Life on arginine for Mycoplasma hominis: clues from its minimal genome and comparison with other human urogenital mycoplasmas.
abstract: Mycoplasma hominis is an opportunistic human mycoplasma. Two other pathogenic human species, M. genitalium and Ureaplasma parvum, reside within the same natural niche as M. hominis: the urogenital tract. These three species have overlapping, but distinct, pathogenic roles. They have minimal genomes and, thus, reduced metabolic capabilities characterized by distinct energy-generating pathways. Analysis of the M. hominis PG21 genome sequence revealed that it is the second smallest genome among self-replicating free living organisms (665,445 bp, 537 coding sequences (CDSs)). Five clusters of genes were predicted to have undergone horizontal gene transfer (HGT) between M. hominis and the phylogenetically distant U. parvum species. We reconstructed M. hominis metabolic pathways from the predicted genes, with particular emphasis on energy-generating pathways. The Embden-Meyerhoff-Parnas pathway was incomplete, with a single enzyme absent. We identified the three proteins constituting the arginine dihydrolase pathway. This pathway was found essential to promote growth in vivo. The predicted presence of dimethylarginine dimethylaminohydrolase suggested that arginine catabolism is more complex than initially described. This enzyme may have been acquired by HGT from non-mollicute bacteria. Comparison of the three minimal mollicute genomes showed that 247 CDSs were common to all three genomes, whereas 220 CDSs were specific to M. hominis, 172 CDSs were specific to M. genitalium, and 280 CDSs were specific to U. parvum. Within these species-specific genes, two major sets of genes could be identified: one including genes involved in various energy-generating pathways, depending on the energy source used (glucose, urea, or arginine) and another involved in cytadherence and virulence. Therefore, a minimal mycoplasma cell, not including cytadherence and virulence-related genes, could be envisaged containing a core genome (247 genes), plus a set of genes required for providing energy. For M. hominis, this set would include 247+9 genes, resulting in a theoretical minimal genome of 256 genes.
authors.affiliation: Université de Bordeaux, Laboratoire de Bactériologie EA 3671, Bordeaux, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Pereyre
authors.forename: Pascal
authors.initials: P
authors.lastname: Sirand-Pugnet
authors.forename: Laure
authors.initials: L
authors.lastname: Beven
authors.forename: Alain
authors.initials: A
authors.lastname: Charron
authors.forename: Hélène
authors.initials: H
authors.lastname: Renaudin
authors.forename: Aurélien
authors.initials: A
authors.lastname: Barré
authors.forename: Philippe
authors.initials: P
authors.lastname: Avenaud
authors.forename: Daniel
authors.initials: D
authors.lastname: Jacob
authors.forename: Arnaud
authors.initials: A
authors.lastname: Couloux
authors.forename: Valérie
authors.initials: V
authors.lastname: Barbe
authors.forename: Antoine
authors.initials: A
authors.lastname: de Daruvar
authors.forename: Alain
authors.initials: A
authors.lastname: Blanchard
authors.forename: Cécile
authors.initials: C
authors.lastname: Bébéar
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism*; D050260:Carbohydrate Metabolism / Q000235:genetics; D002448:Cell Adhesion / Q000235:genetics; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D006801:Humans; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D045704:Mycoplasma genitalium / Q000235:genetics / Q000378:metabolism; D019535:Mycoplasma hominis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014509:Ureaplasma / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000235:genetics
chemical_list: D001120:Arginine