A recently transferred cluster of bacterial genes in Trichomonas vaginalis--lateral gene transfer and the fate of acquired genes

• Published in: BMC evolutionary biology Vol. 14; no. 1; p. 119
• Main Authors: Strese, Ake, Backlund, Anders, Alsmark, Cecilia
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 05.06.2014; BioMed Central
• Subjects: Acquisitions & mergers; Analysis; Bacteria; Bacteria - classification; Bacteria - genetics; Bacterial genetics; Deoxyribonucleic acid; DNA; Drug resistance; Eukaryotes; Evolution, Molecular; Firmicutes; Gene Transfer, Horizontal; Genes; Genes, Bacterial; Genetic aspects; Genetic engineering; Genome, Protozoan; Genomes; Lateral gene transfer (LGT); Multigene Family; Parasites; Peptoniphilus; Peptoniphilus harei; Phylogenetics; Phylogeny; Physiological aspects; Trichomonas; Trichomonas vaginalis; Trichomonas vaginalis - genetics
• ISSN: 1471-2148; 1471-2148
• DOI: 10.1186/1471-2148-14-119

Lateral Gene Transfer (LGT) has recently gained recognition as an important contributor to some eukaryote proteomes, but the mechanisms of acquisition and fixation in eukaryotic genomes are still uncertain. A previously defined norm for LGTs in microbial eukaryotes states that the majority are genes involved in metabolism, the LGTs are typically localized one by one, surrounded by vertically inherited genes on the chromosome, and phylogenetics shows that a broad collection of bacterial lineages have contributed to the transferome. A unique 34 kbp long fragment with 27 clustered genes (TvLF) of prokaryote origin was identified in the sequenced genome of the protozoan parasite Trichomonas vaginalis. Using a PCR based approach we confirmed the presence of the orthologous fragment in four additional T. vaginalis strains. Detailed sequence analyses unambiguously suggest that TvLF is the result of one single, recent LGT event. The proposed donor is a close relative to the firmicute bacterium Peptoniphilus harei. High nucleotide sequence similarity between T. vaginalis strains, as well as to P. harei, and the absence of homologs in other Trichomonas species, suggests that the transfer event took place after the radiation of the genus Trichomonas. Some genes have undergone pseudogenization and degradation, indicating that they may not be retained in the future. Functional annotations reveal that genes involved in informational processes are particularly prone to degradation. We conclude that, although the majority of eukaryote LGTs are single gene occurrences, they may be acquired in clusters of several genes that are subsequently cleansed of evolutionarily less advantageous genes.