Analysis of complete genome sequence of Neorickettsia risticii: causative agent of Potomac horse fever.
Abstract: Neorickettsia risticii is an obligate intracellular bacterium of the trematodes and mammals. Horses develop Potomac horse fever (PHF) when they ingest aquatic insects containing encysted N. risticii-infected trematodes. The complete genome sequence of N. risticii Illinois consists of a single circular chromosome of 879 977 bp and encodes 38 RNA species and 898 proteins. Although N. risticii has limited ability to synthesize amino acids and lacks many metabolic pathways, it is capable of making major vitamins, cofactors and nucleotides. Comparison with its closely related human pathogen N. sennetsu showed that 758 (88.2%) of protein-coding genes are conserved between N. risticii and N. sennetsu. Four-way comparison of genes among N. risticii and other Anaplasmataceae showed that most genes are either shared among Anaplasmataceae (525 orthologs that generally associated with housekeeping functions), or specific to each genome (>200 genes that are mostly hypothetical proteins). Genes potentially involved in the pathogenesis of N. risticii were identified, including those encoding putative outer membrane proteins, two-component systems and a type IV secretion system (T4SS). The bipolar localization of T4SS pilus protein VirB2 on the bacterial surface was demonstrated for the first time in obligate intracellular bacteria. These data provide insights toward genomic potential of N. risticii and intracellular parasitism, and facilitate our understanding of PHF pathogenesis.
Publication Date: 2009-08-06 PubMed ID: 19661282PubMed Central: PMC2764437DOI: 10.1093/nar/gkp642Google Scholar: Lookup
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Summary
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This research investigates the complete genome sequence of Neorickettsia risticii, a bacterium that causes Potomac horse fever in horses. The study provides insights into the genomic potential of N. risticii and its function as an intracellular parasite, contributing to a better understanding of the pathogenesis of Potomac horse fever.
Introduction to Neorickettsia risticii
- Neorickettsia risticii is an obligate intracellular bacterium. Essentially, it cannot survive outside a host cell.
- Horses are vulnerable to Potomac horse fever (PHF) when they ingest aquatic insects that carry N. ristici-infected trematodes.
Genomic Analysis of N. risticii
- The complete genome sequence of the N. risticii Illinois strain was discovered to have a single circular chromosome consisting of 879,977 base pairs (bp).
- The genome encodes 38 RNA species and 898 proteins.
- Interestingly, while N. risticii has limited abilities for amino acid synthesis and lacks many metabolic pathways, it can manufacture major vitamins, cofactors, and nucleotides.
Comparative Genomic Analysis
- When compared to a closely related human pathogen, N. sennetsu, it was found that 88.2% or 758 of protein-coding genes are conserved across both species.
- A four-way comparison of genes among N. risticii and other Anaplasmataceae, a family of bacteria, showed that most genes are either common to Anaplasmataceae, or unique to each genome.
Identification of Pathogenesis-Related Genes
- The study managed to identify genes that are potentially implicated in the pathogenesis of N. risticii. These include genes for putative outer membrane proteins, two-component systems, and a type IV secretion system (T4SS).
- This research also demonstrated for the first time, the bipolar localization of the T4SS pilus protein VirB2 on the bacterial surface in intracellular bacteria.
Conclusion
- The comprehensive genome analysis of N. risticii provides valuable insights into its genomic potential and capacity as an intracellular parasite. This can further our understanding of PHF pathogenesis, aiding in the development of effective therapeutic interventions.
Cite This Article
APA
Lin M, Zhang C, Gibson K, Rikihisa Y.
(2009).
Analysis of complete genome sequence of Neorickettsia risticii: causative agent of Potomac horse fever.
Nucleic Acids Res, 37(18), 6076-6091.
https://doi.org/10.1093/nar/gkp642 Publication
Researcher Affiliations
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.
MeSH Terms
- Anaplasmataceae / genetics
- Anaplasmataceae Infections / microbiology
- Bacterial Outer Membrane Proteins / genetics
- Bacterial Proteins / genetics
- Base Sequence
- Cell Wall / chemistry
- DNA Repair
- Genome, Bacterial
- Molecular Sequence Data
- Neorickettsia risticii / genetics
- Neorickettsia risticii / metabolism
- Neorickettsia risticii / pathogenicity
- Sequence Analysis, DNA
- Transcription, Genetic
Grant Funding
- R01 AI 47885 / NIAID NIH HHS
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