Major membrane surface proteins of Mycoplasma hyopneumoniae selectively modified by covalently bound lipid

Abstract

Surface protein antigens of Mycoplasma hyopneumoniae were identified by direct antibody-surface binding or by radioimmunoprecipitation of surface '25I-labeled proteins with a series of monoclonal antibodies (MAbs). Surface proteins p70, p65, p50, and p44 were shown to be integral membrane components by selective partitioning into the hydrophobic phase during Triton X-114 (TX-114)-phase fractionation, whereas p41 was concomitantly identified as a surface protein exclusively partitioning into the aqueous phase. Radioimmunoprecipitation of TX-114-phase proteins from cells labeled with [35S]methionine, "4C-amino acids, or [3H] palmitic acid showed that proteins p65, p50, and p44 were abundant and (with one other hydrophobic protein, p60) were selectively labeled with lipid. Covalent lipid attachment was established by high-performance liquid chromatography identffication of [3H]methyl palmitate after acid methanolysis of delipidated proteins. An additional, unidentified methanolysis product suggested conversion of palmitate to another form of lipid also attached to these proteins. Alkaline hydroxylamine treatment of labeled proteins indicated linkage of lipids by amide or stable 0-linked ester bonds. Proteins p65, p50, and p44 were highly immunogenic in the natural host as measured by immunoblots of TX-114-phase proteins with antisera from swine inoculated with whole organisms. These proteins were antigenically and structurally unrelated, since hyperimmune mouse antibodies to individual gel-purified proteins were monospecific and gave distinct proteolytic epitope maps. Intraspecies size variants of one surface antigen of M. hyopneumoniae were revealed by a MAb to p70 (defined in strain J, ATCC 25934), which recognized a larger p73 component on strain VPP11 (ATCC 25617). In addition, MAb to internal, aqueous-phase protein p82 of strain J failed to bind an analogous antigen in strain VPP11. These studies establish that a highly restricted set of distinct, lipid-modified hydrophobic membrane proteins are major surface antigens of M. hyopneumoniae and that structural variants of surface antigens occur within this species.

The Vlp system of Mycoplasma hyorhinis: combinatorial expression of distinct size variant lipoproteins generating high-frequency surface antigenic variation

“…This more easily observed morphotype (28) TX-114 phase partitioning of radiolabeled mycoplasma proteins. TX-114 (Boehringer GmbH, Mannheim, Germany) phase partitioning was performed by the procedure of Bordier (4), as adapted to mycoplasmas and described in detail elsewhere (7,27,28,44). Briefly, metabolically labeled mycoplasmas from 0.5 ml of original culture were solubilized at 4°C for 1 to 2 h in 200 ,lI of PBS containing 1% (wt/vol) TX-114 and 0.5 mM phenylmethylsulfonyl fluoride.…”

“…SDS-PAGE was performed by the method of Laemmli (23) with 8% 0.75-mm gels containing 3% urea (36). Samples were treated at 100°C for 5 min under reducing conditions (27,44). Gels containing radiolabeled proteins were stained with Coomassie blue (44) and fluorographed by a variation of the technique of Bonner and Laskey (3) as described elsewhere (7,44).…”

“…Gels containing radiolabeled proteins were stained with Coomassie blue (44) and fluorographed by a variation of the technique of Bonner and Laskey (3) as described elsewhere (7,44). Relative molecular masses were calculated from standard markers (44). For immunoblotting, SDS-PAGEseparated proteins were electrophoretically transferred to nitrocellulose membrane filters and immunostained as described above for colony blots, using MAbs to VlpB and VlpC (as described above) or MAb to VlpB/C as undiluted hybridoma culture fluid.…”

“…Samples were treated at 100°C for 5 min under reducing conditions (27,44). Gels containing radiolabeled proteins were stained with Coomassie blue (44) and fluorographed by a variation of the technique of Bonner and Laskey (3) as described elsewhere (7,44). Relative molecular masses were calculated from standard markers (44).…”

The Genome Sequence ofMycoplasma hyopneumoniaeStrain 232, the Agent of Swine Mycoplasmosis

“…The cellular adhesin that mediates specific attachment to swine cilia was not identified until the mid-1990s (66), and only recently has the molecular basis of adherence been studied (18)(19)(20)34). There are many aspects of adherence and interaction with host cells that remain largely unexplored (33,40,65), and even the surface architecture of this mycoplasma species has not been fully evaluated (48,51,59,60; T. A. Burnett, S. J. Cordwell, S. J. Geary, M. F. Walker, F. C. Minion, and S. P. Djordjevic, Abstr. 14th Congr.…”