Sequestration of SerRS through LLPS Impairs Localized Translation and Contributes to Antibiotic Persistence

Antibiotic-tolerant persisters contribute to the emergence of resistance, posing a significant challenge to the efficacy of antibiotic therapies. Despite extensive research, the mechanisms underlying persistence remain inadequately understood. By tracking the evolution of exponential-phase bacterial populations subjected to intermittent high-dose ertapenem exposure, we characterized the evolved strains in terms of tolerance. Mutant strains, harboring mutations in the seryl-tRNA synthetase gene (serS), exhibited abrupt growth arrest upon serine depletion during exponential growth, resembling the persistence phenotype induced by serine hydroxamate (SHX). Under serine starvation, the mutated SerRS protein was sequestrated into liquid-liquid phase separation (LLPS)-driven condensates, disrupting their composition and impairing localized translation. This event precipitated growth arrest and dormancy in the SerST strain, triggering persistence. Our findings reveal an unrecognized role for aminoacyl-tRNA synthetases (aaRSs) in modulating bacterial condensates and provide insights into the molecular mechanisms underlying bacterial persistence. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=165 SRC="FIGDIR/small/630848v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@1a69521org.highwire.dtl.DTLVardef@188b087org.highwire.dtl.DTLVardef@fd897forg.highwire.dtl.DTLVardef@14e1b6a_HPS_FORMAT_FIGEXP M_FIG SerRS Recruitment Disrupts Localized Translation in DeaD-marked Condensates. Upon serine starvation, SerRST partitions into LLPS-driven DeaD-marked condensates, impairing their localized translation activity and suggesting mechanisms underlying persistence arising during exponential phase. These evolutionarily conserved condensates orchestrate a robust translation program to enable stress responses and instruct cell fate decisions in bacterial populations. C_FIG