T-armless tRNAs and elongated elongation factor Tu

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• Transfer RNAs (tRNAs) typically possess a conserved secondary structure including a T arm, D arm, anticodon arm, and acceptor stem.
• Certain mitochondrial tRNAs, particularly in nematodes and some animals, lack the T arm, posing a challenge for canonical protein synthesis.
• Canonical elongation factor Tu (EF-Tu) binding relies on the T arm of tRNA.

Purpose of the Study:

• To investigate the mechanism by which T-armless mitochondrial tRNAs are utilized in translation.
• To elucidate the role of a unique EF-Tu variant (EF-Tu1) in nematode mitochondrial translation.
• To explore the evolutionary origins of T-armless tRNAs and their associated proteins.

Main Methods:

• Biochemical analysis of mitochondrial tRNAs and EF-Tu from various nematode species.
• Sequence analysis of nuclear and mitochondrial DNA in arthropods.
• Structural analysis of EF-Tu1 from Caenorhabditis elegans.

Main Results:

• Mitochondria of Caenorhabditis elegans possess a unique EF-Tu (EF-Tu1) with a C-terminal extension.
• EF-Tu1 appears to recognize the D-arm of truncated tRNAs, bypassing the need for a T arm.
• Evidence suggests T-armless tRNAs may have evolved through EF-Tu gene duplication events.

Conclusions:

• The discovery of EF-Tu1's D-arm recognition mechanism explains translation with T-armless tRNAs.
• T-armless tRNAs likely arose from EF-Tu gene duplication, highlighting RNA-protein co-evolution.
• These findings offer significant insights into the adaptability of the translation machinery.