Extended Data Figure 6. Changes in base pairing partially explain the consequences on fitness of single mutations.

a, A single mutation can either lose or restore a canonical Watson-Crick base pairing (WC bp) depending on the background context. b, Percentage of deleterious or beneficial single mutations (at FDR<0.1) that restore or lose a canonical WC bp in any base pairing position of the tRNA. From total of 4,300 mutations that restore WC bp, 721 are beneficial and 498 deleterious. 13,195 mutations result in the lost of a canonical WC pair (n = 6,806 mutations that create a Wobble bp and n = 6,389 that completely break the bp interaction), of these 3,030 and 721 have significant deleterious and beneficial effects respectively. WC – Watson-Crick, W – Wobble and L – lost bp. c, Same as b but split by mutation identity. d, Distribution of the effects of mutations in the tRNA Acceptor stem that break a base pairing (left, n = 1,356 single mutations with background fitness >-0.15) have more deleterious effects when the neighbour base pairing positions are composed of one or more Wobble interactions (n = 921), instead of all canonical WC pairings (n = 435, average fitness effect difference = 0.028, Welch two-sided t-test p-value shown). The context of the base pairing of the stem is illustrated at the right.