trnHGUG

trnHGUG refers to the mitochondrial transfer RNA gene that encodes histidine and uses the anticodon GUG. In many metazoan mitochondrial genomes, this gene is designated as trnH(GUG) and is one of the set of tRNA genes encoded by the mitochondrial DNA. It functions as part of the organelle’s translation system, delivering histidine to ribosomes during protein synthesis.

Structure and function involve the typical tRNA cloverleaf architecture that is matured from a primary transcript. In mitochondria, tRNA genes are usually transcribed as part of long polycistronic transcripts and then processed to yield mature tRNA molecules. The trnH(GUG) tRNA is charged with histidine by histidyl-tRNA synthetase and recognizes histidine codons during mitochondrial translation.

Genomic distribution and context vary across taxa. The trnH(GUG) gene is widespread in animal mitochondrial genomes and is also found in plants and fungi, though its exact location and neighboring genes can differ due to lineage-specific rearrangements. In many species, it is encoded on the heavy strand of the mitochondrial genome.

Evolution and significance: mitochondrial tRNA genes, including trnH(GUG), exhibit evolutionary variation in sequence and gene order that can inform phylogenetic analyses. Mutations within this gene can impact tRNA structure or charging efficiency, potentially affecting mitochondrial protein synthesis and contributing to mitochondrial dysfunction in some organisms. Overall, trnH(GUG) is a compact, essential component of the mitochondrial translation apparatus in species that retain this gene.