title: AdeR protein regulates adeABC expression by binding to a direct-repeat motif in the intercistronic spacer.
abstract: Overexpression of the efflux pump AdeABC is associated with tigecycline resistance of multi-drug resistant Acinetobacter baumannii (MDRAB). A two-component regulatory system, sensor AdeS and regulator AdeR proteins regulate the pump. However, the detailed mechanism of the AdeR protein to enhance the expression of adeABC operon is not well defined. We illustrated the biological characteristics of AdeR proteins by comparing a mutant AdeR protein of a tigecycline resistant MDRAB to the wild AdeR protein. By analyzing a series of deletion constructs, a minimal gene cassette of the intercistronic spacer DNA fragment specifically bound with the adeR protein and resulted in band shifting in electrophoresis mobility shifting assays (EMSA). A conserve direct repeat motif was observed in the intercistronic spacer DNA. We demonstrated the AdeR protein was a direct-repeat-binding protein. Two common residue mutations on the AdeR proteins of tigecycline resistant MDRAB isolates could reduce their binding affinity with the intercistronic spacer. The free intercistronic spacer may then more efficiently support the read-through of the adeABC operon during the co-transcriptional translation in tigecycline resistant MDRAB isolates.
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan; Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Tein-Yao
authors.initials: TY
authors.lastname: Chang
authors.affiliation: Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Pathology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Bo-Jun
authors.initials: BJ
authors.lastname: Huang
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan; Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Jun-Ren
authors.initials: JR
authors.lastname: Sun
authors.affiliation: Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Cherng-Lih
authors.initials: CL
authors.lastname: Perng
authors.affiliation: Infection Control Office, Tri-Service General Hospital, Taipei, Taiwan.
authors.forename: Ming-Chin
authors.initials: MC
authors.lastname: Chan
authors.affiliation: Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Cheng-Ping
authors.initials: CP
authors.lastname: Yu
authors.affiliation: Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Pathology, National Defense Medical Center, Taipei, Taiwan. Electronic address: drche0523@gmail.com.
authors.forename: Tzong-Shi
authors.initials: TS
authors.lastname: Chiueh
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D020816:Amino Acid Motifs; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000235:genetics; D004586:Electrophoresis / Q000379:methods; D017353:Gene Deletion; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives / Q000494:pharmacology; D009154:Mutation; D009876:Operon; D012091:Repetitive Sequences, Nucleic Acid; D017421:Sequence Analysis; D013753:Tetracycline Resistance; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D026901:Membrane Transport Proteins; D000078304:Tigecycline; D008911:Minocycline
keywords: Acinetobacter baumannii; AdeABC efflux pump; AdeR; Two component system