Abstract.
Many eukaryotic nuclear genomes as well as mitochondrial plasmids contain genes displaying evident sequence similarity to those encoding the single-subunit RNA polymerase (ssRNAP) of bacteriophage T7 and its relatives. We have collected and aligned these ssRNAP sequences and have constructed unrooted phylogenetic trees that demonstrate the separation of ssRNAPs into three well-defined and nonoverlapping clusters (phage-encoded, nucleus-encoded, and plasmid-encoded). Our analyses indicate that these three subfamiles of T7-like RNAPs shared a common ancestor; however, the order in which the groups diverged cannot be inferred from available data. On the basis of structural similarities and mutational data, we suggest that the ancestral ssRNAP gene may have arisen via duplication and divergence of a DNA polymerase or reverse transcriptase gene. Considering the current phylogenetic distribution of ssRNAP sequences, we further suggest that the origin of the ancestral ssRNAP gene closely paralleled in time the introduction of mitochondria into eukaryotic cells through a eubacterial endosymbiosis.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Author information
Authors and Affiliations
Additional information
Received: 28 April 1997 / Accepted: 11 August 1997
Rights and permissions
About this article
Cite this article
Cermakian, N., Ikeda, T., Miramontes, P. et al. On the Evolution of the Single-Subunit RNA Polymerases. J Mol Evol 45, 671–681 (1997). https://doi.org/10.1007/PL00006271
Issue Date:
DOI: https://doi.org/10.1007/PL00006271