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Characterization of the variability of a 75-kDa membrane protein in Mycoplasma hominis
T Mygind1, S Birkelund, G Christiansen
1Department of Medical Microbiology and Immunology, University of Aahus, DK-8000, Denmark.
Abstract:
The gene p75 encoding a 75-kDa surface-exposed membrane protein P75 was cloned and sequenced from Mycoplasma hominis type strain PG21T. To investigate the intraspecies variability, sequences were obtained from an additional two isolates 7488 and 183, and the three sequences were compared. The nucleotide and amino acid differences were not confined to specific regions of the gene/protein, but when comparing the three sequences, differences were present as single site substitutions or small insertions or deletions of nucleotides/amino acids. The intraspecies variability was further investigated by restriction enzyme analysis with two restriction enzymes (Alul and MboII) of PCR products amplified from p75 from 28 M. hominis isolates. On the basis of band patterns produced by the two restriction enzymes, the isolates could be divided into five and six groups. These groups neither matched categories of the M. hominis vaa gene nor the M. hominis p120 gene classes, indicating that the three genes vary by different mechanisms and possibly indicating horizontal gene transfer. Federation of European Microbiological Societies.
Insights
The Mycoplasma hominis p75 gene shows significant intraspecies variability. Restriction enzyme analysis revealed distinct genetic groups, suggesting different evolutionary mechanisms and potential horizontal gene transfer.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Mycoplasma hominis is a common human pathogen.
- The p75 gene encodes a surface-exposed membrane protein crucial for M. hominis.
- Understanding intraspecies variability is key to pathogen characterization.
Purpose of the Study:
- To clone and sequence the p75 gene from Mycoplasma hominis.
- To investigate the intraspecies genetic variability of the p75 gene.
- To compare the variability of p75 with other M. hominis genes (vaa and p120).
Main Methods:
- Gene cloning and sequencing of p75 from M. hominis isolates.
- Nucleotide and amino acid sequence comparison.
- Polymerase Chain Reaction (PCR) amplification of p75.
- Restriction enzyme analysis (AluI and MboII) of PCR products.
Main Results:
- Sequencing revealed nucleotide and amino acid differences, including substitutions and small indels.
- Restriction enzyme analysis of 28 isolates divided them into five and six distinct groups.
- These genetic groupings did not correlate with M. hominis vaa or p120 gene classes.
Conclusions:
- The p75 gene exhibits considerable intraspecies variability in Mycoplasma hominis.
- The distinct genetic patterns suggest varied evolutionary mechanisms for different genes.
- The findings may indicate horizontal gene transfer events within M. hominis populations.