Highly dynamic genomic loci drive the synthesis of two types of capsular or secreted polysaccharides within the Mycoplasma mycoides cluster.
Mycoplasmas of the Mycoplasma mycoides cluster are all ruminant pathogens. Mycoplasma mycoides subsp. mycoides is responsible for contagious bovine pleuropneumonia and is known to produce capsular polysaccharide (CPS) and exopolysaccharide (EPS). Previous studies have strongly suggested a role for Mycoplasma mycoides subsp. mycoides polysaccharides in pathogenicity. Mycoplasma mycoides subsp. mycoides-secreted EPS was recently characterized as a β(1→6)-galactofuranose homopolymer (galactan) identical to the capsular product. Here, we extended the characterization of secreted polysaccharides to all other members of the M. mycoides cluster: M. capricolum subsp. capripneumoniae, M. capricolum subsp. capricolum, M. leachii, and M. mycoides subsp. capri (including the LC and Capri serovars). Extracted EPS was characterized by nuclear magnetic resonance, resulting in the identification of a homopolymer of β(1→2)-glucopyranose (glucan) in M. capricolum subsp. capripneumoniae and M. leachii. Monoclonal antibodies specific for this glucan and for the Mycoplasma mycoides subsp. mycoides-secreted galactan were used to detect the two polysaccharides. While M. mycoides subsp. capri strains of serovar LC produced only capsular galactan, no polysaccharide could be detected in strains of serovar Capri. All strains of M. capricolum subsp. capripneumoniae and M. leachii produced glucan CPS and EPS, whereas glucan production and localization varied among M. capricolum subsp. capricolum strains. Genes associated with polysaccharide synthesis and forming a biosynthetic pathway were predicted in all cluster members. These genes were organized in clusters within two loci representing genetic variability hot spots. Phylogenetic analysis showed that some of these genes, notably galE and glf, were acquired via horizontal gene transfer. These findings call for a reassessment of the specificity of the serological tests based on mycoplasma polysaccharides.
CIRAD, UMR CMAEE, Montpellier, France INRA, UMR1309 CMAEE, Montpellier, France.
Clothilde
C
Bertin
Unité Biologie des Plantes et Innovation, EA 3900, Université de Picardie Jules Verne, Amiens, France.
Corinne
C
Pau-Roblot
Unité Biologie des Plantes et Innovation, EA 3900, Université de Picardie Jules Verne, Amiens, France.
Josiane
J
Courtois
CIRAD, UMR CMAEE, Montpellier, France INRA, UMR1309 CMAEE, Montpellier, France.
Lucía
L
Manso-Silván
Agence Nationale de Sécurité Sanitaire, Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Lyon, France Université de Lyon, VetAgro Sup, UMR Mycoplasmoses des Ruminants, Marcy-L'étoile, France.
Florence
F
Tardy
Agence Nationale de Sécurité Sanitaire, Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Lyon, France Université de Lyon, VetAgro Sup, UMR Mycoplasmoses des Ruminants, Marcy-L'étoile, France.
François
F
Poumarat
INRA, UMR 1225, IHAP, Toulouse, France Université de Toulouse, INP, ENVT, UMR1225, IHAP, Toulouse, France.
Christine
C
Citti
INRA, UMR 1332 de Biologie du Fruit et Pathologie, Villenave d'Ornon, France Université de Bordeaux, UMR 1332 de Biologie du Fruit et Pathologie, Villenave d'Ornon, France.
Pascal
P
Sirand-Pugnet
Agence Nationale de Sécurité Sanitaire, Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Lyon, France Université de Lyon, VetAgro Sup, UMR Mycoplasmoses des Ruminants, Marcy-L'étoile, France.
Patrice
P
Gaurivaud
CIRAD, UMR CMAEE, Montpellier, France INRA, UMR1309 CMAEE, Montpellier, France thiaucourt@cirad.fr.
François
F
Thiaucourt
D000818:Animals; D002417:Cattle; D016000:Cluster Analysis; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D056426:Genetic Loci; D016680:Genome, Bacterial; D009682:Magnetic Resonance Spectroscopy; D009176:Mycoplasma mycoides / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D017385:Sequence Homology
D011135:Polysaccharides, Bacterial