title: Surface localized glyceraldehyde-3-phosphate dehydrogenase of Mycoplasma genitalium binds mucin.
abstract: Mycoplasma genitalium is the smallest known self-replicating cell. It was first isolated from urethral specimens in individuals with non-gonococcal urethritis and, more recently, from respiratory and synovial sites. Our laboratory has been interested in defining the mechanisms by which M. genitalium adheres to and colonizes host cell surfaces. In order to determine potential targets of adherence, we examined the interaction of M. genitalium with a primary component of the mucosal epithelial lining, mucin (Mn). Three Mn-binding proteins (MnBPs) of M. genitalium were isolated by affinity chromatography. One of these proteins was identified by N-terminal sequencing as glyceraldehyde-3-phosphate dehy-drogenase (GAPDH). Antiserum raised against recombinant GAPDH blocked binding of intact biosynthetically labelled mycoplasmas to mucin by approximately 70%. Whole cell radioimmunoprecipitation indicated that GAPDH was surface-accessible and surface localization of GAPDH was further verified by membrane fractionation and immunoelectron microscopy. The role of GAPDH as an adhesin to Mn not only provides insights into the organism's mechanisms of adherence and colonization but also into its ability to maximize its limited genome.
authors.affiliation: Department of Microbiology and Immunology, 7703 Floyd Curl Drive, The University of Texas Health Science Center at San Antonio, 78229-3900, USA.
authors.forename: René A
authors.initials: RA
authors.lastname: Alvarez
authors.forename: Mark W
authors.initials: MW
authors.lastname: Blaylock
authors.forename: Joel B
authors.initials: JB
authors.lastname: Baseman
mesh_terms: D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D009077:Mucins / Q000378:metabolism*; D009174:Mycoplasma / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D009175:Mycoplasma Infections / Q000382:microbiology; D011233:Precipitin Tests; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D009077:Mucins; D011994:Recombinant Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases