Novel Codon-Anticodon Recognition Patterns in Mycoplasma capricolum

Abstract

The tRNA anticodon list for an extremely AT-rich bacterium, Mycoplasma capricolum, is unique and may be characterized by (1) removal of all the non-obligate CNN anticodons, (2) the presence of UNN (U, unmodified) anticodons in all family boxes, except arginine family box, (3) appearance of anticodon AGU for threonine colon ACU, (4) removal of GNN anticodons from family boxes, (5) occurrence of arginine anticodon ICG as in other bacteria and yet probable disappearance of anticodon CCG from arginine family box that would have resulted in CGG colon unassigned, and (6) development of anticodon *UCA that has led to the use of the universal stop colon UGA as a tryptophan colon. The above-mentioned deviation of the genetic code in Mycoplasma from the codes in other eubacteria, such as in E. coli and B. subtilis, may be explained by strong AT-directional mutation pressure that has been exerted to the Mycoplasma genome.