Abstract
Dictyostelium discoideum, the model organism for the evolutionary supergroup of Amoebozoa, is a social amoeba that, upon starvation, undergoes transition from a unicellular to a multicellular organism. In its genome, we identified two genes encoding for tRNA nucleotidyltransferases. Such pairs of tRNA nucleotidyltransferases usually represent collaborating partial activities catalyzing CC- and A-addition to the tRNA 3′-end, respectively. In D. discoideum, however, both enzymes exhibit identical activities, representing bona-fide CCA-adding enzymes. Detailed characterization of the corresponding activities revealed that both enzymes seem to be essential and are regulated inversely during different developmental stages of D. discoideum. Intriguingly, this is the first description of two functionally equivalent CCA-adding enzymes using the same set of tRNAs and showing a similar distribution within the cell. This situation seems to be a common feature in Dictyostelia, as other members of this phylum carry similar pairs of tRNA nucleotidyltransferase genes in their genome.
Highlights
Transfer RNA nucleotidyltransferases belong to the polymerase β superfamily [1,2,3]
Motif C is discussed as a spring element involved in the structural reorganization of the catalytic core required for high fidelity polymerization [20,21], while motif E likely contributes to the stabilization of the NTP binding pocket and might interact with the Transfer RNA (tRNA) primer [11]
The existence of two genes cca1 and cca2 encoding for putative tRNA nucleotidyltransferases in Dictyostelium discoideum was described [22,44]. To clarify whether this situation represents a common feature in the group of Dictyostelia, we analyzed annotated genomes of Acytostelium subglobosum, Cavenderia fasciculata, Dictyostelium discoideum, Dictyostelium purpureum, Heterostelium album and Tieghemostelium lacteum
Summary
Transfer RNA (tRNA) nucleotidyltransferases belong to the polymerase β superfamily [1,2,3] They are responsible for synthesis, maintenance and repair of the CCA sequence at the 3 -end of tRNAs [3,4], which is essential for the attachment of amino acids, recognition by elongation factors and correct positioning of the aminoacyl-tRNA in the ribosome [5,6]. Our data show for the first time that this organism relies on the presence of two enzymes with bona-fide CCA-adding activity Both enzyme versions are not separated into a nuclear/cytosolic and a mitochondrial form and do not show significant differences in tRNA substrate preference within the life cycle of D. discoideum, they both seem to be essential. This might hint at the participation of both CCA-adding activities in the fine-tuning of the complex developmental cycle, as was shown for a remarkable number of other isoenzymes in D. discoideum [37,38,39,40,41,42,43]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
