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The stability of cytadherence proteins in Mycoplasma pneumoniae requires activity of the protein kinase PrkC.

ABSTRACT: Mycoplasma pneumoniae belongs to the mollicutes, a group of bacteria that have strongly reduced genomes but that are nevertheless capable of independent life. With only three transcription factors, the regulatory features of these bacteria are very limited. Thus, posttranslational regulation might be important for M. pneumoniae. In addition to the highly specific HPr kinase, the M. pneumoniae prkC gene encodes the serine/threonine protein kinase C. In order to study the function(s) of this kinase, we isolated an M. pneumoniae mutant affected in PrkC. This mutation resulted in nonadherent growth and loss of cytotoxicity. Examination of the phosphorylation profile of the prkC mutant suggested that phosphorylation of cytadherence proteins was affected by the loss of this kinase. In contrast, inactivation of the prpC gene affecting the protein phosphatase that antagonizes PrkC-dependent phosphorylation resulted in more intensive phosphorylation of the cytadherence proteins HMW1 and HMW3 of the major adhesin P1 and of the surface protein MPN474. Moreover, loss of PrkC affects not only the phosphorylation state of the cytadherence proteins but also their intracellular accumulation. However, the expression of the corresponding genes was not affected by PrkC, suggesting that PrkC-dependent phosphorylation results in stabilization of the cytadherence proteins. The HMW proteins and P1 are part of the so-called terminal organelle of M. pneumoniae that is involved in gliding motility, cell division, and adhesion to host epithelial tissues. Our observations suggest that the posttranslational modification of cytadherence proteins by PrkC is essential for the development and function of the M. pneumoniae terminal organelle.

SUBMITTER: Schmidl SR

PROVIDER: S-EPMC2798226 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

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The stability of cytadherence proteins in Mycoplasma pneumoniae requires activity of the protein kinase PrkC.

Schmidl Sebastian R SR Gronau Katrin K Hames Claudine C Busse Julia J Becher Dörte D Hecker Michael M Stülke Jörg J

Infection and immunity 20091026 1

Mycoplasma pneumoniae belongs to the mollicutes, a group of bacteria that have strongly reduced genomes but that are nevertheless capable of independent life. With only three transcription factors, the regulatory features of these bacteria are very limited. Thus, posttranslational regulation might be important for M. pneumoniae. In addition to the highly specific HPr kinase, the M. pneumoniae prkC gene encodes the serine/threonine protein kinase C. In order to study the function(s) of this kinas ...[more]

PMID: 19858294

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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

The stability of cytadherence proteins in Mycoplasma pneumoniae requires activity of the protein kinase PrkC.

Publications

The stability of cytadherence proteins in Mycoplasma pneumoniae requires activity of the protein kinase PrkC.

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