title: Identification of two glycosylated components of Mycoplasma penetrans: a surface-exposed capsular polysaccharide and a glycolipid fraction.
abstract: Among the wall-less mycoplasmas only a few species have been identified with a capsule at their cell surface. Mycoplasma penetrans is a recently identified mycoplasma with unique morphology, isolated from HIV-infected patients. Using transmission electron microscopy, it was found that M. penetrans is surrounded by capsular material 11 nm (strain GTU-54-6A1) to 30 nm (strain HF-2) thick, which can be stained with ruthenium red and labelled with cationized ferritin. The polysaccharide composition of this capsule was indicated by its staining with periodic acid-thiocarbohydrazide silver proteinate and the abolition of ruthenium red staining of the cell surface by neuraminidase treatment. In addition, proteinase K treatment of the M. penetrans cells resulted in removal of the capsule, suggesting that polypeptides may contribute in anchoring it to the membrane or in its stability. Two different types of glycosylated material were detected in mycoplasma extracts by SDS-PAGE and periodic acid-Schiff staining. The first component was a high-molecular-mass material, which was heat- and proteinase-K-labile and which probably constitutes the capsular polymer. The other component was a low-molecular-mass glycolipid fraction, which was proteinase-K-, heat- and EDTA-resistant. The identification of a capsule at the M. penetrans cell surface is of particular interest for a mycoplasma which has been shown to adhere to various host cells and to penetrate into their intracellular compartments. The capsule may have significance in the pathogenesis of disease associated with infection by this organism.
authors.affiliation: Unité d'Oncologie Virale28, rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Neyrolles
authors.affiliation: Unité d'Oncologie Virale28, rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Brenner
authors.affiliation: Unité d'Oncologie Virale28, rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Prevost
authors.affiliation: Laboratoire des Aspergillus Institut Pasteur, 28, rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Fontaine
authors.affiliation: Unité d'Oncologie Virale28, rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Montagnier
authors.affiliation: Unité d'Oncologie Virale28, rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Blanchard
mesh_terms: D016667:Bacterial Capsules / Q000032:analysis* / Q000737:chemistry / Q000648:ultrastructure; D004396:Coloring Agents; D004591:Electrophoresis, Polyacrylamide Gel; D019286:Endopeptidase K / Q000378:metabolism; D005293:Ferritins; D006001:Glycoconjugates / Q000032:analysis; D006017:Glycolipids / Q000032:analysis*; D006801:Humans; D008854:Microscopy, Electron; D018661:Mycoplasma penetrans / Q000737:chemistry* / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure*; D010503:Periodic Acid-Schiff Reaction; D012430:Ruthenium Red
chemical_list: D004396:Coloring Agents; D006001:Glycoconjugates; D006017:Glycolipids; D012430:Ruthenium Red; D005293:Ferritins; D019286:Endopeptidase K