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Mycoplasma pneumoniae protein P30 is required for cytadherence and associated with proper cell development.

ABSTRACT: The attachment organelle of Mycoplasma pneumoniae is a polar, tapered cell extension containing an intracytoplasmic, electron-dense core. This terminal structure is the leading end in gliding motility, and its duplication is thought to precede cell division, raising the possibility that mutations affecting cytadherence also confer a defect in motility or cell development. Mycoplasma surface protein P30 is associated with the attachment organelle, and P30 mutants II-3 and II-7 do not cytadhere. In this study, the recombinant wild-type but not the mutant II-3 p30 allele restored cytadherence when transformed into P30 mutants by recombinant transposon delivery. The mutations associated with loss of P30 in mutant II-3 and reacquisition of P30 in cytadhering revertants thereof were identified by nucleotide sequencing of the p30 gene. Morphological abnormalities that included ovoid or multilobed cells having a poorly defined tip structure were associated with loss of P30. Digital image analysis confirmed quantitatively the morphological differences noted visually. Transformation of the P30 mutants with the wild-type p30 allele restored a normal morphology, as determined both visually and by digital image analysis, suggesting that P30 plays a role in mycoplasma cell development. Finally, the P30 mutants localized the adhesin protein P1 to the terminal organelle, indicating that P30 is not involved in P1 trafficking but may be required for its receptor-binding function.

SUBMITTER: Romero-Arroyo CE

PROVIDER: S-EPMC93483 | biostudies-literature | 1999 Feb

REPOSITORIES: biostudies-literature

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Mycoplasma pneumoniae protein P30 is required for cytadherence and associated with proper cell development.

Romero-Arroyo C E CE Jordan J J Peacock S J SJ Willby M J MJ Farmer M A MA Krause D C DC

Journal of bacteriology 19990201 4

The attachment organelle of Mycoplasma pneumoniae is a polar, tapered cell extension containing an intracytoplasmic, electron-dense core. This terminal structure is the leading end in gliding motility, and its duplication is thought to precede cell division, raising the possibility that mutations affecting cytadherence also confer a defect in motility or cell development. Mycoplasma surface protein P30 is associated with the attachment organelle, and P30 mutants II-3 and II-7 do not cytadhere. I ...[more]

PMID: 9973332

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Project description:The gene for a 30-kDa immunodominant antigen, P30, of Mycoplasma agalactiae was cloned from type strain PG2 and expressed in Escherichia coli. P30 is encoded on a monocistronic operon determined by two -10 boxes and a possible -35 region constituting the potential promoter, and a transcription termination site. The gene for the 266-amino-acid protein is preceded by a polypurine-rich region designed as the consensus sequence for a ribosome-binding site. Analysis of the amino acid sequence of P30 revealed the presence of a recognition site for a prokaryotic signal peptidase II at amino acid (aa) 24, indicating that P30 is a transmembrane protein. Moreover, Triton X-114 phase partitioning of M. agalactiae PG2 total antigen revealed that P30 is strongly hydrophobic and hence a possible membrane component. Immunoblot analysis using the monospecific polyclonal anti-P30-His serum indicated that P30 is specific to M. agalactiae. Furthermore, PCR amplification with specific primers for p30 and Southern blot analysis revealed the presence of the gene in all M. agalactiae strains tested and its absence in the other mycoplasma species. Among 27 strains of M. agalactiae studied, 20 strains belonging to the common serotypes A to D, including PG2, expressed P30 or part of it as detected by the monospecific polyclonal anti-P30 antibodies. The other seven strains belonging to the rarely isolated serotypes E to H were negative for P30. The p30 gene was sequenced in 15 strains of M. agalactiae, 10 of which expressed P30 or at least part of it and 5 of which did not express P30. The negative strains carried mutations in both -10 boxes of the promoters. These mutations seem to be responsible for the lack of P30 expression in these strains. Analysis of sera from sheep that were experimentally infected with M. agalactiae revealed that P30 induced a strong and persistent immune response which was still very high two months after infection. In contrast, currently used enzyme-linked immunosorbent assay serology gave only low titers.

Project description:The Mycoplasma pneumoniae hmw3 gene was sequenced and its gene product was characterized with the goal of elucidating the functional role of HMW3 as an accessory component in cytadherence. A total of 2,016 bp of the hmw3 locus was sequenced, revealing an open reading frame large enough to encode a 672-amino-acid protein with a molecular weight of 73,725. No consensuslike ribosome binding or promoter sequences were identified. However, hmw3 was flanked by upstream and downstream open reading frames. Gene identity was confirmed by comparing the deduced amino acid sequence with the amino acid sequence obtained directly from N-terminal amino acid sequencing of HMW3. Analysis of the deduced amino acid sequence indicated an acidic pI (4.4), an unusual distribution of charged residues, a high degree of hydrophilicity, and a high proline content for HMW3. M. pneumoniae protein profiles obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) following culturing in the presence of [3H]Pro were consistent with the high Pro content predicted for HMW3 and indicated the same for cytadherence accessory protein HMW1. A discrepancy existed between the predicted size of HMW3 (Mr, 73,725) and the size of HMW3 obtained by SDS-PAGE (Mr, 140,000). Variable electrophoretic mobility in SDS-PAGE was observed at different acrylamide concentrations for HMW3, indicating that anomalous migration might account for the size discrepancy. The relative mobility of HMW3 was enhanced only slightly in the presence of magnesium acetate, suggesting that the unusual charge distribution might only be partially responsible for the anomalous migration. Secondary structure predictions were dominated by beta-sheets and nonrepetitive turns or coils, suggesting a probable extended, rigid conformation for HMW3. Finally, an unusual, highly acidic domain (residues 180 to 280) which might have particular functional significance relative to the role of HMW3 as a cytadherence accessory protein was identified.

Dataset Information

Mycoplasma pneumoniae protein P30 is required for cytadherence and associated with proper cell development.

Publications

Mycoplasma pneumoniae protein P30 is required for cytadherence and associated with proper cell development.

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