Switching a conflicted bacterial DTD-tRNA code is essential for the emergence of mitochondria

Abstract

Optimization of DTD-tRNA code and mito-tRNA(Gly) discriminator base is important for emergence of mitochondria.

“Superwobbling” and tRNA-34 Wobble and tRNA-37 Anticodon Loop Modifications in Evolution and Devolution of the Genetic Code

“…Escherichia coli, however, appears to be a reasonable model, albeit with several differences from the endosymbiont that became the mitochondria. We support the hypothesis that eukaryotic mitochondria were derived from an α-proteobacterial endosymbiont within an Asgard Archaea [11,51]. Eukaryotes, however, arose as a complex set of genetic fusions of multiple Archaea and multiple Bacteria.…”

“…It appears to us that eukaryogenesis was tortured, involving many endosymbiotic and other large horizontal gene transfer events, only some of which resulted in identified eukaryotic organelles. Apparently, contributions were made to the process by many archaeal and many bacterial genes and, also, the genetic fusions were balanced by many compensating eukaryotic innovations [11]. The FECA to LECA bottleneck is reflected in the evolution of aaRS enzymes through eukaryo-genesis (Table 1) [51].…”

“…In the eukaryotic cytosol, the genetic code reflects the fusion of an Asgard Archaea and the α-proteobacterial endosymbiont that became the mitochondria [6,[8][9][10][11] (Figure 6). A major feature in evolution of the eukaryotic cytosol is the expansion of the A34→I34 strategy (beige shading in Figure 6).…”

“…The story is tangled because of 1) (sometimes multiple) horizontal gene transfers; 2) multiple archaeal and bacterial contributions to the eukaryotic genetic make-up; 3) eukaryotic genetic innovations; and 4) coevolution of cytosolic and mitochondrial tRNAs and aaRS enzymes. A recent paper describes molecular events associated with eukaryogenesis [11]. Generally, cytosolic tRNAs are thought to have archaeal origins and mitochondrial tRNAs probably have an α-proteobacterial origin.…”

“…Phylogenetics indicates pathways of evolution of Archaea, ancient Bacteria, derived Bacteria and Eukarya [5,6]. Evolution of the mitochondria from a bacterial endosymbiont is fundamental to understand evolution of Eukarya [7][8][9][10][11]. Superwobbling indicates the importance of ancient wobble U34 methylation-based modifications at the 5-carbon position.…”