{"doi":"10.1128/mbio.02955-25","title":"<i>Mycobacterium tuberculosis</i> growth arrest on propionate at acidic pH is suppressed by mutations in <i>phoPR</i> and pyrazinamide treatment","abstract":"ABSTRACT Mycobacterium tuberculosis (Mtb) arrests its growth at acidic pH when grown on specific single carbon sources, including propionate. However, Mtb grows well on propionate at pH 7.0, supporting that propionate can support growth as a sole carbon source. To understand the basis of the propionate-driven growth arrest at acidic pH, we performed a forward genetic selection for mutants that enable growth on propionate at pH 5.7. All the selected mutants had insertions in the two-component regulatory genes phoR or phoP . We hypothesized that growth arrest at acidic pH is caused by PhoPR diverting carbon from central carbon metabolism toward lipid anabolism and that when PhoPR is inactivated, growth is promoted through metabolizing propionate by the methylcitrate cycle (MCC) into pyruvate, a permissive carbon source for growth at acidic pH. Using chemical inhibition and mutants of the MCC pathway, we demonstrate that the enhanced growth is dependent on the MCC. Furthermore, stimulating lipid synthesis via the methylmalonyl-CoA pathway by adding vitamin B12 restricts growth in the ΔphoPR mutant. Conversely, restricting lipid anabolism by inhibiting the triacylglycerol synthase tgs1 enhances the growth of the ΔphoPR mutant. Notably, CoA pools increased in the ΔphoPR mutant grown on propionate, directly supporting our model. Given the role of CoA metabolism in pyrazinamide sensitivity, we examined Mtb sensitivity to pyrazinamide on propionate at acidic pH and, surprisingly, observed that pyrazinamide treatment of wild-type Mtb suppresses growth arrest on propionate at acidic pH. In contrast, the Δ phoPR mutant has enhanced sensitivity to pyrazinamide. Together, these findings support that propionate-driven growth arrest at acidic pH is caused by metabolic remodeling that is regulated by PhoPR and is associated with pyrazinamide sensitivity. IMPORTANCE When grown on certain single carbon sources, such as propionate, Mycobacterium tuberculosis (Mtb) arrests its growth at acidic pH and establishes a state of non-replicating persistence. To understand the genetic basis of this growth restriction, a genetic selection was performed to identify mutants unable to arrest growth at acidic pH with propionate as a sole carbon source. The selection exclusively identified mutants in the PhoPR two-component regulatory system, which functions to modulate cell envelope lipids and redox homeostasis through the upregulation of lipid synthesis at acidic pH. Using genetic and chemical inhibition studies, we demonstrate that PhoPR arrests growth at acidic pH by diverting carbon away from the methyl citrate cycle toward lipid anabolism. Surprisingly, treatment of Mtb with pyrazinamide at acidic pH on propionate also enabled growth. Therefore, this study defines new mechanisms by which Mtb integrates environmental signaling to regulate growth, metabolism, and drug susceptibility. These findings are relevant to pathogenesis, as PhoPR is essential for growth in macrophages and animals, environments with varying pH and carbon source availability, depending on immune pressures. These data suggest that drug susceptibility may be impacted by enhanced growth and metabolic capacity of Mtb in acidic and propionate-rich environments, such as within the macrophage or the granuloma.","journal":"mBio","year":2025,"id":549022,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9618,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":765306,"name":"Shelby J. Dechow","orcid":null,"position":1,"is_corresponding":false},{"id":1090999,"name":"Bassel J. Abdalla","orcid":null,"position":2,"is_corresponding":false},{"id":312550,"name":"Robert B. Abramovitch","orcid":"0000-0002-4119-4169","position":3,"is_corresponding":false},{"id":1090998,"name":"Heather M. Murdoch","orcid":null,"position":0,"is_corresponding":true}],"reference_count":48,"raw_metadata":null,"created_at":"2026-07-19T02:54:03.053965Z","pmid":"41313006","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}