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On the evolution of the single-subunit RNA polymerases
N Cermakian1, T M Ikeda, P Miramontes
1Département de biochimie, Université de Montréal, Canada.
Journal of Molecular Evolution
|February 21, 1998
Summary
Scientists identified three distinct groups of single-subunit RNA polymerase (ssRNAP) genes in eukaryotes, suggesting a shared ancestry. These phage-like RNAP genes likely originated from DNA polymerases or reverse transcriptases.
Area of Science:
- Molecular Biology
- Genomics
- Evolutionary Biology
Background:
- Eukaryotic genomes contain genes similar to bacteriophage T7's single-subunit RNA polymerase (ssRNAP).
- These ssRNAP genes are found in nuclear genomes, mitochondrial plasmids, and bacteriophages.
Purpose of the Study:
- To investigate the evolutionary origins and relationships of ssRNAP genes.
- To determine the phylogenetic distribution and ancestral state of ssRNAP genes.
Main Methods:
- Sequence alignment of ssRNAP genes from various sources.
- Construction of unrooted phylogenetic trees to infer evolutionary relationships.
Main Results:
- ssRNAP sequences clustered into three distinct groups: phage-encoded, nucleus-encoded, and plasmid-encoded.
- Phylogenetic analysis indicated a common ancestor for these three ssRNAP subfamilies.
- The evolutionary divergence order of these groups could not be determined.
Conclusions:
- The ancestral ssRNAP gene likely arose from duplication and divergence of DNA polymerase or reverse transcriptase genes.
- The origin of the ancestral ssRNAP gene may be linked to the endosymbiotic event that introduced mitochondria into eukaryotic cells.