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Molecular cloning and characterization of an adherence-related operon of Mycoplasma genitalium
S P Reddy1, W G Rasmussen, J B Baseman
1Department of Microbiology, University of Texas Health Science Center at San Antonio 78284-7758, USA.
Abstract:
Adhesins and adhesin-related accessory proteins of pathogenic mycoplasmas are required for cytadherence and the subsequent development of disease pathology. The classic example has been Mycoplasma pneumoniae, which causes primary atypical pneumonia in humans. Mutants of M. pneumoniae defective in adhesins (P1 and P30) or in adherence-accessory proteins (HMW1 through HMW4) are unable to colonize host tissues and are avirulent. Mycoplasma genitalium, implicated in nongonococcal, nonchlamydial urethritis, pneumonia, arthritis, and AIDS progression, was found to encode a 140-kDa adhesin that shared both DNA and protein sequence similarities with P1, a major adhesin of M. pneumoniae. In this report, we show that M. genitalium possesses additional homolog sequences to well-characterized adherence-related genes and proteins of M. pneumoniae. The M. genitalium homologs are designated P32 and P69 and correspond to P30 and HMW3 of M. pneumoniae, respectively (J. B. Baseman, p. 243-259, in S. Rottem and I. Kahane, ed., Subcellular biochemistry, vol. 20. Mycoplasma cell membranes, 1993, and D. C. Krause, D. K. Leith, R. M. Wilson, and J. B. Baseman, Infect. Immun. 35:809-817, 1982). Interestingly, the operon-like organizations of P32 and P69 in the M. genitalium genome are similar to the organizations of P30 and HMW3 genes of M. pneumoniae, suggesting that the conservation of these adherence-related genes and proteins might have occurred through horizontal gene transfer events originating from an ancestral gene family.
Insights
Pathogenic mycoplasmas use adhesins for host cell attachment and disease. Mycoplasma genitalium shares adherence genes with Mycoplasma pneumoniae, suggesting horizontal gene transfer.
Area of Science:
- Microbiology
- Molecular Biology
- Pathogenesis
Background:
- Adhesins and related proteins are crucial for pathogenic mycoplasmas' cytadherence and disease development.
- Mycoplasma pneumoniae causes pneumonia, with adhesins (P1, P30) and accessory proteins (HMW1-4) essential for virulence.
- Mycoplasma genitalium is linked to various diseases, including urethritis and pneumonia.
Purpose of the Study:
- To investigate adherence-related genes and proteins in Mycoplasma genitalium.
- To compare these genes with those found in Mycoplasma pneumoniae.
- To explore the evolutionary origins of these conserved adherence factors.
Main Methods:
- Sequence analysis of Mycoplasma genitalium genome.
- Identification of homologs to Mycoplasma pneumoniae adherence-related genes.
- Comparison of gene organization and sequence similarity.
Main Results:
- Mycoplasma genitalium encodes a 140-kDa adhesin similar to M. pneumoniae P1.
- Homologs designated P32 and P69 in M. genitalium correspond to M. pneumoniae P30 and HMW3.
- The operon-like organization of P32 and P69 in M. genitalium mirrors that of P30 and HMW3 in M. pneumoniae.
Conclusions:
- Mycoplasma genitalium possesses adherence-related genes homologous to those of Mycoplasma pneumoniae.
- The conserved gene organization suggests potential horizontal gene transfer events.
- These findings shed light on the evolution and conservation of mycoplasma virulence factors.