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Sequence divergence in the ORF6 gene of Mycoplasma pneumonia
K Ruland1, R Himmelreich, R Herrmann
1Zentrum für Molekulare Biologie, University of Heidelberg, Germany.
Abstract:
The ORF6 gene product of Mycoplasma pneumoniae is involved in a yet-unknown manner in the adhesion of the bacterium to its host cell. Part of the ORF6 gene is a repetitive DNA sequence (RepMP5), about 1,900 bp long. Seven additional similar copies of RepMP5 are dispersed on the genome. In the independently isolated strains M. pneumoniae M129 and FH, the RepMP5 copies residing in the ORF6 gene are not identical. Two conserved regions, ranging from nucleotides 1 to 799 and from nucleotide 1795 to the end of the gene, border a variable region, ranging from nucleotides 800 to 1794. This variable region differs in DNA sequence and by 201 bp. Analysis of RepMP5 copies outside the ORF6 gene showed that both M. pneumoniae M129 and M. pneumoniae FH carry a RepMP5 copy on a 6-kbp EcoRI fragment which has the same DNA sequence as the variable region of RepMP5 in the M. pneumoniae FH ORF6 gene. According to these data, a switch from the M. pneumoniae M129 ORF6 gene to the M. pneumoniae FH ORF6 gene could take place by gene conversion.
Insights
Mycoplasma pneumoniae
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- The ORF6 gene product of Mycoplasma pneumoniae plays a role in host cell adhesion.
- The ORF6 gene contains a repetitive DNA sequence, RepMP5, approximately 1,900 bp long.
- Seven additional RepMP5 copies are distributed throughout the Mycoplasma pneumoniae genome.
Purpose of the Study:
- To investigate the variations within the RepMP5 sequences in different strains of Mycoplasma pneumoniae.
- To understand the potential mechanisms of genetic exchange involving the ORF6 gene and RepMP5 sequences.
Main Methods:
- Comparative DNA sequence analysis of the RepMP5 regions within the ORF6 gene of M. pneumoniae strains M129 and FH.
- Analysis of RepMP5 copies located outside the ORF6 gene in both strains.
- Identification of conserved and variable regions within the RepMP5 sequences.
Main Results:
- The RepMP5 copies within the ORF6 gene of M. pneumoniae M129 and FH strains exhibit sequence differences in a variable region (nucleotides 800-1794).
- This variable region differs by 201 bp between the two strains.
- A RepMP5 copy found on a 6-kbp EcoRI fragment outside the ORF6 gene in both strains shares the same sequence as the variable region of the M. pneumoniae FH ORF6 gene.
Conclusions:
- The observed sequence similarities suggest that gene conversion may facilitate the exchange of ORF6 gene sequences between Mycoplasma pneumoniae strains.
- This genetic mechanism could contribute to the variability observed in the RepMP5 regions and potentially influence bacterial adhesion properties.