An extreme mutational hotspot in nlpD depends on transcriptional induction of rpoS.

ABSTRACT: Mutation rate varies within and between genomes. Within genomes, tracts of nucleotides, including short sequence repeats and palindromes, can cause localised elevation of mutation rate. Additional mechanisms remain poorly understood. Here we report an instance of extreme mutational bias in Pseudomonas fluorescens SBW25 associated with a single base-pair change in nlpD. These mutants frequently evolve in static microcosms, and have a cell-chaining (CC) phenotype. Analysis of 153 replicate populations revealed 137 independent instances of a C565T loss-of-function mutation at codon 189 (CAG to TAG (Q189*)). Fitness measures of alternative nlpD mutants did not explain the deterministic evolution of C565T mutants. Recognising that transcription can be mutagenic, and that codon 189 overlaps with

SUBMITTER: Farr AD 

PROVIDER: S-EPMC11838912 | biostudies-literature | 2025 Jan

REPOSITORIES: biostudies-literature