The ancestor of modern Holozoa acquired the CCA-adding enzyme from Alphaproteobacteria by horizontal gene transfer

Transfer RNAs (tRNAs) require the absolutely conserved sequence motif CCA at their 3'-ends, representing the site of aminoacylation. In the majority of organisms, this trinucleotide sequence is not encoded in the genome and thus has to be added post-transcriptionally by the CCA-adding enzyme, a...

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Bibliographic Details
Published in:Nucleic acids research 2015-08, Vol.43 (14), p.6739-6746
Main Authors: Betat, Heike, Mede, Tobias, Tretbar, Sandy, Steiner, Lydia, Stadler, Peter F, Mörl, Mario, Prohaska, Sonja J
Format: Article
Language:English
Subjects:
Alphaproteobacteria - classification
Alphaproteobacteria - genetics
Animals
Choanoflagellata - genetics
Computational Biology
Eukaryota - classification
Eukaryota - genetics
Evolution, Molecular
Gene Transfer, Horizontal
Phylogeny
RNA Nucleotidyltransferases - genetics
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Summary:Transfer RNAs (tRNAs) require the absolutely conserved sequence motif CCA at their 3'-ends, representing the site of aminoacylation. In the majority of organisms, this trinucleotide sequence is not encoded in the genome and thus has to be added post-transcriptionally by the CCA-adding enzyme, a specialized nucleotidyltransferase. In eukaryotic genomes this ubiquitous and highly conserved enzyme family is usually represented by a single gene copy. Analysis of published sequence data allows us to pin down the unusual evolution of eukaryotic CCA-adding enzymes. We show that the CCA-adding enzymes of animals originated from a horizontal gene transfer event in the stem lineage of Holozoa, i.e. Metazoa (animals) and their unicellular relatives, the Choanozoa. The tRNA nucleotidyltransferase, acquired from an α-proteobacterium, replaced the ancestral enzyme in Metazoa. However, in Choanoflagellata, the group of Choanozoa that is closest to Metazoa, both the ancestral and the horizontally transferred CCA-adding enzymes have survived. Furthermore, our data refute a mitochondrial origin of the animal tRNA nucleotidyltransferases.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gkv631