{"doi":"10.1128/jb.00045-20","title":"Characterization of RelA in<i>Acinetobacter baumannii</i>","abstract":"ABSTRACT In response to nutrient depletion, the RelA and SpoT proteins generate the signaling molecule (p)ppGpp, which then controls a number of downstream effectors to modulate cell physiology. In Acinetobacter baumannii strain AB5075, a relA ortholog ( ABUW_3302 ) was identified by a transposon insertion that conferred an unusual colony phenotype. An in-frame deletion in relA (Δ relA ) failed to produce detectable levels of ppGpp when amino acid starvation was induced with serine hydroxamate. The Δ relA mutant was blocked from switching from the virulent opaque colony variant (VIR-O) to the avirulent translucent colony variant (AV-T), but the rate of AV-T to VIR-O switching was unchanged. In addition, the Δ relA mutation resulted in a pronounced hypermotile phenotype on 0.35% agar plates. This hypermotility was dependent on the activation of a LysR regulator ABUW_1132, which was required for expression of AbaR, a LuxR family quorum-sensing regulator. In the Δ relA mutant, ABUW_1132 was also required for the increased expression of an operon composed of the ABUW_3766-ABUW_3773 genes required for production of the surfactant-like lipopeptide acinetin 505. Additional phenotypes identified in the Δ relA mutant included (i) cell elongation at high density, (ii) reduced formation of persister cells tolerant to colistin and rifampin, and (iii) decreased virulence in a Galleria mellonella model. IMPORTANCE Acinetobacter baumannii is a pathogen of worldwide importance. Due to the increasing prevalence of antibiotic resistance, these infections are becoming increasingly difficult to treat. New therapies are required to combat multidrug-resistant isolates. The role of RelA in A. baumannii is largely unknown. This study demonstrates that like in other bacteria, RelA controls a variety of functions, including virulence. Strategies to inhibit the activity of RelA and the resulting production of ppGpp could inhibit virulence and may represent a new therapeutic approach.","journal":"Journal of Bacteriology","year":2020,"id":99823,"datarank":1.1260185155885925,"base_score":3.4011973816621555,"endowment":3.4011973816621555,"self_citation_contribution":0.5101796072493234,"citation_network_contribution":0.6158389083392691,"self_endowment_contribution":0.5101796072493234,"citer_contribution":0.6158389083392691,"corpus_percentile":null,"corpus_rank":null,"citation_count":29,"citer_count":27,"citers_with_citation_signal":25,"citers_with_endowment":25,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9551,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":491456,"name":"Aimee R. P. Tierney","orcid":null,"position":1,"is_corresponding":false},{"id":480598,"name":"Ju-Sim Kim","orcid":"0000-0001-7926-9560","position":2,"is_corresponding":false},{"id":480599,"name":"Andrés Vázquez‐Torres","orcid":"0000-0002-6181-4185","position":3,"is_corresponding":false},{"id":272343,"name":"Philip N. Rather","orcid":"0000-0001-9674-6250","position":4,"is_corresponding":false},{"id":490737,"name":"María Pérez−Varela","orcid":"0000-0003-0990-4041","position":0,"is_corresponding":true}],"reference_count":64,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T22:38:09.754371Z","pmid":"32229531","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":[]}