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Identification and sequence analysis of Treponema pallidum tprJ, a member of a polymorphic multigene family
L V Stamm1, S R Greene, H L Bergen
1Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill 27599-7400, USA. lstamm@email.unc.edu
Abstract:
TnphoA mutagenesis was used to identify genes encoding exported proteins in a genomic DNA library of Treponema pallidum, the syphilis agent. The nucleotide sequence of an open reading frame (tprJ) that encodes a 755-amino acid protein with a predicted molecular mass of 81.1 kDa was determined. The deduced amino acid sequence of TprJ has homology to the major surface protein of Treponema denticola, a periodontal pathogen. Southern hybridization and genomic DNA sequence analysis indicate that tprJ is a member of a polymorphic multigene family. RT-PCR data showed that tprJ is expressed in treponemes during syphilitic infection. A putative tprJ gene was sequenced from T. pertenue, the closely related yaws agent. The deduced amino acid sequence of T. pertenue TprJ is 87.3% identical to that of T. pallidum TprJ. This is the first report of significant sequence differences within homologous genes of T. pallidum and T. pertenue.
Insights
Researchers identified the tprJ gene in Treponema pallidum, the syphilis bacterium, revealing its role as an exported protein. This gene family shows significant sequence differences between syphilis and yaws agents.
Area of Science:
- Microbiology
- Genomics
- Molecular Biology
Background:
- Treponema pallidum is the causative agent of syphilis.
- Identifying exported proteins is crucial for understanding bacterial pathogenesis and developing diagnostics/therapeutics.
Purpose of the Study:
- To identify genes encoding exported proteins in Treponema pallidum using TnphoA mutagenesis.
- To characterize the tprJ gene and its product, TprJ.
- To investigate the evolutionary relationship between T. pallidum and T. pertenue homologous genes.
Main Methods:
- TnphoA mutagenesis for gene identification.
- Nucleotide sequencing of the tprJ open reading frame.
- Bioinformatic analysis for amino acid homology and multigene family identification (Southern hybridization, genomic DNA sequence analysis).
- Reverse transcription-polymerase chain reaction (RT-PCR) for gene expression analysis.
- Sequencing of the homologous gene in Treponema pertenue.
Main Results:
- Identification and sequencing of the tprJ gene encoding an 81.1 kDa exported protein.
- TprJ shows homology to the major surface protein of Treponema denticola.
- tprJ belongs to a polymorphic multigene family within T. pallidum.
- tprJ is expressed during syphilitic infection.
- The homologous T. pertenue TprJ protein shares 87.3% identity with T. pallidum TprJ.
Conclusions:
- The tprJ gene encodes a novel exported protein in Treponema pallidum.
- The tprJ gene is part of a polymorphic multigene family and is expressed during infection.
- Significant sequence divergence exists between homologous tprJ genes of T. pallidum and T. pertenue, offering insights into the evolution of these pathogenic treponemes.