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Query: UMLS:C0026936 (Mycoplasma)
 14,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoclonal antibodies (MAbs) previously shown to recognize distinct epitopes selectively expressed on the surface of some Mycoplasma hyorhinis strains were used to define two discrete sets of lipid-modified membrane surface proteins showing marked size variation within this species. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis of Triton X-114 phase-fractionated proteins from six isolates of M. hyorhinis defined a set of amphiphilic integral membrane proteins of 23, 50, and 55 kilodaltons (kDa) recognized on respective isolates by one MAb and a second set of integral proteins of 88, 120, and 100 to 150 kDa recognized by another MAb. The first group of proteins all contained a common, amphiphilic 18-kDa limit tryptic polypeptide bearing the epitope. The size- and strain-variant surface antigens identified by the MAbs were shown to be lipid-modified proteins. Phase fractionation of [3H]palmitate-labeled organisms revealed numerous 3H-labeled proteins in all isolates, which partitioned exclusively into the hydrophobic phase. These proteins generally showed pronounced size variation among isolates and included the antigen variants recognized by the two MAbs, as demonstrated directly by immunoprecipitation of correspondingly sized 3H-labeled proteins from each isolate. A third MAb recognized an invariant, lipid-associated surface protein of 70 kDa on all M. hyorhinis isolates. Covalent modification of lipid-associated proteins was confirmed by identifying 3H-labeled methyl palmitate after acid methanolysis of Triton X-114 phase proteins derived from [3H]palmitate-labeled organisms. However, removal of covalently bound lipid from chloroform-methanol-extracted proteins by alkaline hydroxylamine was selective; complete removal was observed with only a few proteins, possibly including the 120-kDa form of one antigen variant. This suggested potential differences in the nature of covalent linkage among lipid-modified M. hyorhinis surface antigens. Intraspecies antigen variants described here in M. hyorhinis share some characteristics with size-variant antigens reported in phylogenetically related gram-positive eubacteria and may contribute to phenotypic diversification and differences in pathogenicity of mycoplasmas.
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PMID:Lipid-modified surface protein antigens expressing size variation within the species Mycoplasma hyorhinis. 246 38

Surface protein antigens of Mycoplasma hyopneumoniae were identified by direct antibody-surface binding or by radioimmunoprecipitation of surface 125I-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, 14C-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 identification 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 O-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.
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PMID:Major membrane surface proteins of Mycoplasma hyopneumoniae selectively modified by covalently bound lipid. 368 Jan 70

Three strains of Mycoplasma, M. laidlawii A and B, and Mycoplasma sp. A60549, were grown in broth containing sodium acetate-1-C(14). The methyl esters of the phospholipid fatty acids of harvested radioactive cells were prepared and identified by comparison of their mobilities to known radioactive fatty acid methyl esters by use of a modified reversed-phase partition-thin layer chromatographic technique. No radioactive methyl oleate or methyl linoleate was detected. Compounds migrating as radioactive methyl myristate, stearate, palmitate, and, with less certainty, laurate and octanoate were detected. The qualitative findings for all three organisms appeared similar. M. laidlawii B synthesized a radioactive substance, presumably a saturated fatty acid detected as the methyl ester derivative, which migrated in a position intermediate to methyl myristate-1-C(14) and methyl palmitate-1-C(14). This work indicates that M. laidlawii A and B and Mycoplasma sp. A60549 are capable, in a complex medium containing fatty acids, of synthesizing saturated but not unsaturated fatty acids entirely or in part from acetate.
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PMID:Synthesis of saturated long chain fatty acids from sodium acetate-1-C14 by Mycoplasma. 602 May 66

The major unidentified polar lipid (compound X), recently demonstrated in the cell membrane of Mycoplasma fermentans, was purified by preparative silicic acid column chromatography. Chemical analyses of acid-hydrolyzed compound X revealed that, in addition to fatty acids, it contains glycerol, choline and phosphate in a molar ratio of approximately 1:1:2, and an amino acid that has a retention time similar to that of homoserine. The methylated fatty acid fraction of compound X was subjected to gas-liquid chromatography and revealed methyl palmitate and methyl stearate in a 4.6:1 molar ratio. The structure of compound X was further analyzed by combining mass spectrometry, 31P-NMR and 1H-NMR. The positive and negative fast atom bombardment spectra showed a major component of M(r) 1048 and a minor component of M(r) 1076. Two different phosphate groups were identified in each of the components by 31P-NMR. Fast atom bombardment, tandem mass spectrometry, negative and positive chemical ionization mass spectrometry together with mass spectra analyses of the water-soluble and ether-soluble products obtained by methanolysis has shown that, in addition to palmitic and stearic acid residues, the presence of glycerol, ribitol, cholinephosphate and homoserinephosphate residues. It is suggested that the apparent structure of compound X is either a phosphatidylcholine attached via a phosphotriester bond to a ribitolphosphohomoserine moiety or a phosphatidylhomoserine attached via a phosphotriester bond to a ribitolphosphocholine moiety. The major molecular species is the dipalmitoylderivative (M(r) 1048), whereas the minor molecular species is a stearoyl palmitoyl derivative (M(r) 1076).
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PMID:An unusual polar lipid from the cell membrane of Mycoplasma fermentans. 786 52