Summary of novel dinB alleles.

a Nucleotide changes are represented in the context of the codon in which they reside. Numbers refer to the first and last base in the codon, with position 1 representing the A in the ATG encoding the first amino acid of Pol IV (i.e., 1ATG3).b Allele numbers were assigned by the E. coli Genetic Stock Center (CGSC) at Yale.c The number of times that each mutation was identified is indicated.d Proposed functions for Pol IV residues are based largely on structural insights from Bunting et al. [32], Sharma et al. [53], Boudsocq et al. [54] and Ling et al. [55].e When expressed at high levels from a T7 promoter, recombinant Pol IV mutant proteins were either soluble (+), or poorly soluble and/or extensively proteolyzed (–), as indicated.f One of the three A44D clones identified contained an additional silent mutation at I74 (220ATC222→220ATT222). This allele was not further characterized.g The 937GGG939→GGC substitution present in plasmid pJH154 represents a silent mutation at position G313.h The Pol IV-R75L mutant was expressed as a soluble full-length protein from the T7 promoter, but was inconsistently detected following expression in Pol IVCD from the arabinose promoter of plasmid pDB22, suggesting Pol IVCD-R75L was misfolded.Summary of novel dinB alleles.