The chlamydiae species are distinct from all other Bacteria phylogenetically and in terms of unique division cycle. In earlier studies, a number of examples of genes which have been laterally transferred between Chlamydiae and other organisms have been identified [1-4]. One well-studied example of lateral gene transfer (LGT) is provided by ATP/ADP translocases, which are only found in the chlamydiae, the plant/plastid genomes and the rickettsiae [1,5-7]. The ATP/ADP translocases are required by these intracellular organisms (or organelles) to import host-derived ATP across their cell membrane [5] and their phylogenetic studies indicate that this protein was laterally transferred from chlamydiae to the other groups [1,5].
Two interesting examples of LGTs between a subset of actinobacteria and the chlamydiae were recently discovered by the application of shared presence of prominent conserved indels in two important proteins, serine hydroxymethyltransferase (GlyA) and UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) [8,9]. In phylogenetic trees based on GlyA and MurA proteins, the chlamydiae species branched with high affinity with the actinobacterial species containing the inserts, providing strong evidence that the genes for these proteins containing the inserts have been laterally transferred from an actinobacteria to the chlamydiae. Of particular interest in this case is the observation that the identified inserts in MurA as well as GlyA are present in all Chlamydiales species and they formed a strongly supported subclade within Actinobacteria [8]. These results strongly indicate that the postulated LGT transfer events are very ancient and they likely occurred from an actinobacteria to a common ancestor of the Chlamydiales species.
The phylogenomics analysis of chlamydial proteins has also identified two interesting proteins, whose homologs in addition to various chlamydiae are only found in kinetoplastid protozoa (Trypanosoma and Leishmania) [10]. The genes for these proteins have likely been laterally transferred from chlamydiae to an ancestor of the Trypanosoma and Leishmania [10].
- GlyA:
- MurA
- 16 aa Conserved Insert in MurA common to Chlamydiae and a Subset of Actinobacteria
- Phylogenetic Tree based on MurA protein Sequences
- Proteins uniquely found in Chlamydiae and Protozoa (Trypnaosoma/Leishmania)
Selected References :
Chlamydiae Website: http://www.chlamydiae.com
1. Brinkman, F. S., Blanchard, J. L., Cherkasov, A., Av-Gay, Y., Brunham, R. C., Fernandez, R. C., Finlay, B. B., Otto, S. P., Ouellette, B. F., Keeling, P. J., Rose, A. M., Hancock, R. E., Jones, S. J., and Greberg, H. (2002). Evidence that plant-like genes in Chlamydia species reflect an ancestral relationship between Chlamydiaceae, cyanobacteria, and the chloroplast. Genome Res 12, 1159-1167.
2. Royo, J., Gimez, E., and Hueros, G. (2000). CMP-KDO synthetase: a plant gene borrowed from gram-negative eubacteria. Trends Genet. 16, 432-433.
3. Ortutay, C., Gaspari, Z., Toth, G., Jager, E., Vida, G., Orosz, L., and Vellai, T. (2003). Speciation in Chlamydia: genomewide phylogenetic analyses identified a reliable set of acquired genes. J Mol Evol 57, 672-680.
4. Li, T., Graham, D. E., Stathopoulos, C., Haney, P. J., Kim, H. S., Vothknecht, U., Kitabatake, M., Hong, K. W., Eggertsson, G., Curnow, A. W., Lin, W., Celic, I., Whitman, W., and Soll, D. (1999). Cysteinyl-tRNA formation: the last puzzle of aminoacyl-tRNA synthesis. FEBS Lett. 462, 302-306.
5. Schmitz-Esser, S., Linka, N., Collingro, A., Beier, C. L., Neuhaus, H. E., Wagner, M., and Horn, M. (2004). ATP/ADP translocases: a common feature of obligate intracellular amoebal symbionts related to Chlamydiae and Rickettsiae. J Bacteriol 186, 683-691.
6. Wolf, Y. I., Aravind, L., and Koonin, E. V. (1999). Rickettsiae and Chlamydiae: evidence of horizontal gene transfer and gene exchange. Trends Genet. 15, 173-175.
7. Zomorodipour, A. and Andersson, S. G. (1999). Obligate intracellular parasites: Rickettsia prowazekii and Chlamydia trachomatis. FEBS Lett. 452, 11-15.
8. Griffiths, E. and Gupta, R. S. (2006). Lateral transfers of serine hydroxymethyl transferase (glyA) and UDP-N-acetylglucosamine enolpyruvyl transferase (murA) genes from free-living Actinobacteria to the parasitic chlamydiae. J.Mol.Evol. 63, 283-296.
9. Griffiths, E. and Gupta, R. S. (2002). Protein signatures distinctive of chlamydial species: Horizontal transfer of cell wall biosynthesis genes glmU from Archaebacteria to Chlamydiae, and murA between Chlamydiae and Streptomyces. Microbiology 148, 2541-2549.
10. Gupta, R. S. and Griffiths, E. (2006). Chlamydiae-specific proteins and indels: novel tools for studies. Trends Microbiol.
Citation for this webpage:
Bacterial (Prokaryotic) Phylogeny Webpage (March 2007). http://www.bacterialphylogeny.com/index.html