{"title":"Fluorescent protein sensors illuminate cellular pH changes in Enterobacter cloacae: unravelling the mechanisms of TolC-dependent acid survival.","authors":"Sanchari Chowdhury, Harapriya Mohapatra","doi":"10.1093/femsle/fnag070","DOIUrl":null,"url":null,"abstract":"<p><p>TolC is the outer membrane component of the tripartite RND efflux pump AcrAB-TolC. The underlying mechanism of TolC-dependent acid survival at physiological pH remains unclear. The present study aimed at understanding mechanism of TolC mediated acid survival in logarithmic phase culture of Enterobacter cloacae subsp. cloacae ATCC 13047 not preconditioned to acidic pH. Of the three distinct loci encoding tolC and tolC like proteins, only ECL_04 363 (hereafter referred to as EctolC2) exhibited 86% identity with TolC protein from E. coli K12; deletion of which compromised survival at pH 4.0. Tracking the periplasmic and cytoplasmic pH changes with fluorescent protein sensors indicated deletion of EctolC2 resulted in sustained cytoplasmic acidification and loss of pH homeostasis causing cell death. Exogenous supplementation of lysine significantly rescued acid induced lethality in EcΔtolC2 mutants. ΔmarRAB mutants exhibited slower death rate compared to Δrob mutants; underpinning role of the latter in upregulating EctolC2 at early time point of growth at pH 4.0. Results of the study construe that EctolC2 provides reinforcement to the outer membrane preventing extreme acidification of the periplasm and thereby restoring cytoplasmic pH homeostasis. This study provides significant insight into mechanism of TolC dependent acid survival in E. cloacae.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0000,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Fems Microbiology Letters","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1093/femsle/fnag070","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MICROBIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
TolC is the outer membrane component of the tripartite RND efflux pump AcrAB-TolC. The underlying mechanism of TolC-dependent acid survival at physiological pH remains unclear. The present study aimed at understanding mechanism of TolC mediated acid survival in logarithmic phase culture of Enterobacter cloacae subsp. cloacae ATCC 13047 not preconditioned to acidic pH. Of the three distinct loci encoding tolC and tolC like proteins, only ECL_04 363 (hereafter referred to as EctolC2) exhibited 86% identity with TolC protein from E. coli K12; deletion of which compromised survival at pH 4.0. Tracking the periplasmic and cytoplasmic pH changes with fluorescent protein sensors indicated deletion of EctolC2 resulted in sustained cytoplasmic acidification and loss of pH homeostasis causing cell death. Exogenous supplementation of lysine significantly rescued acid induced lethality in EcΔtolC2 mutants. ΔmarRAB mutants exhibited slower death rate compared to Δrob mutants; underpinning role of the latter in upregulating EctolC2 at early time point of growth at pH 4.0. Results of the study construe that EctolC2 provides reinforcement to the outer membrane preventing extreme acidification of the periplasm and thereby restoring cytoplasmic pH homeostasis. This study provides significant insight into mechanism of TolC dependent acid survival in E. cloacae.
期刊介绍：
FEMS Microbiology Letters gives priority to concise papers that merit rapid publication by virtue of their originality, general interest and contribution to new developments in microbiology. All aspects of microbiology, including virology, are covered.
2019 Impact Factor: 1.987, Journal Citation Reports (Source Clarivate, 2020)
Ranking: 98/135 (Microbiology)
The journal is divided into eight Sections:
Physiology and Biochemistry (including genetics, molecular biology and ‘omic’ studies)
Food Microbiology (from food production and biotechnology to spoilage and food borne pathogens)
Biotechnology and Synthetic Biology
Pathogens and Pathogenicity (including medical, veterinary, plant and insect pathogens – particularly those relating to food security – with the exception of viruses)
Environmental Microbiology (including ecophysiology, ecogenomics and meta-omic studies)
Virology (viruses infecting any organism, including Bacteria and Archaea)
Taxonomy and Systematics (for publication of novel taxa, taxonomic reclassifications and reviews of a taxonomic nature)
Professional Development (including education, training, CPD, research assessment frameworks, research and publication metrics, best-practice, careers and history of microbiology)
If you are unsure which Section is most appropriate for your manuscript, for example in the case of transdisciplinary studies, we recommend that you contact the Editor-In-Chief by email prior to submission. Our scope includes any type of microorganism - all members of the Bacteria and the Archaea and microbial members of the Eukarya (yeasts, filamentous fungi, microbial algae, protozoa, oomycetes, myxomycetes, etc.) as well as all viruses.
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