Accession ARO:3000818
DefinitionNalC is a repressor of PA3720-PA3719, which are positive regulators of MexAB-OprM. Thus, nalC mutants confer multidrug resistance.
AMR Gene Familyresistance-nodulation-cell division (RND) antibiotic efflux pump
Drug Classpeptide antibiotic, diaminopyrimidine antibiotic, penam, sulfonamide antibiotic, cephalosporin, carbapenem, phenicol antibiotic, tetracycline antibiotic, monobactam, fluoroquinolone antibiotic, macrolide antibiotic, aminocoumarin antibiotic, cephamycin, penem
Resistance Mechanismantibiotic efflux
Efflux Componentefflux pump complex or subunit conferring antibiotic resistance
Efflux Regulatorprotein(s) and two-component regulatory system modulating antibiotic efflux
Classification50 ontology terms | Show
+ process or component of antibiotic biology or chemistry
+ antibiotic molecule
+ peptide antibiotic [Drug Class]
+ mechanism of antibiotic resistance
+ beta-lactam antibiotic
+ lipopeptide antibiotic
+ resistance-modifying agents
+ diaminopyrimidine antibiotic [Drug Class]
+ penam [Drug Class]
+ polymyxin antibiotic
+ cephem
+ sulfonamide antibiotic [Drug Class]
+ determinant of antibiotic resistance
+ beta-lactamase inhibitor
+ antibiotic efflux [Resistance Mechanism]
+ cephalosporin [Drug Class]
+ antibiotic mixture
+ clavulanic acid [Adjuvant]
+ carbapenem [Drug Class]
+ colistin
+ phenicol antibiotic [Drug Class]
+ tetracycline antibiotic [Drug Class]
+ trimethoprim [Antibiotic]
+ monobactam [Drug Class]
+ fluoroquinolone antibiotic [Drug Class]
+ amoxicillin [Antibiotic]
+ macrolide antibiotic [Drug Class]
+ efflux pump complex or subunit conferring antibiotic resistance [Efflux Component]
+ sulfamethoxazole [Antibiotic]
+ aminocoumarin antibiotic [Drug Class]
+ trimethoprim-sulfamethoxazole [Antibiotic]
+ cephamycin [Drug Class]
+ ciprofloxacin [Antibiotic]
+ ceftazidime [Antibiotic]
+ aztreonam [Antibiotic]
+ chloramphenicol [Antibiotic]
+ ceftriaxone [Antibiotic]
+ tetracycline [Antibiotic]
+ azithromycin [Antibiotic]
+ penem [Drug Class]
+ resistance-nodulation-cell division (RND) antibiotic efflux pump [AMR Gene Family]
+ panipenem [Antibiotic]
+ meropenem [Antibiotic]
+ novobiocin [Antibiotic]
+ colistin B [Antibiotic]
+ ampicillin [Antibiotic]
+ colistin A [Antibiotic]
+ amoxicillin-clavulanic acid [Antibiotic]
+ erythromycin [Antibiotic]
+ MexAB-OprM
Parent Term(s)3 ontology terms | Show

Cao L, et al. 2004. Mol Microbiol 53(5): 1423-1436. MexAB-OprM hyperexpression in NalC-type multidrug-resistant Pseudomonas aeruginosa: identification and characterization of the nalC gene encoding a repressor of PA3720-PA3719. (PMID 15387820)

Pan YP, et al. 2016. Arch. Microbiol. 198(6):565-71 Overexpression of MexAB-OprM efflux pump in carbapenem-resistant Pseudomonas aeruginosa. (PMID 27060003)

Braz VS, et al. 2016. FEMS Microbiol. Lett. : Mutations in NalC induce MexAB-OprM overexpression resulting in high level of aztreonam resistance in environmental isolates of Pseudomonas aeruginosa. (PMID 27412168)


Prevalence of nalC among the sequenced genomes, plasmids, and whole-genome shotgun assemblies available at NCBI for 88 important pathogens (see methodological details and complete list of analyzed pathogens). Values reflect percentage of genomes, plasmids, or whole-genome shotgun assemblies that have at least one hit to the AMR detection model. Default view includes percentages calculated based on Perfect plus Strict RGI hits. Select the checkbox to view percentages based on only Perfect matches to AMR reference sequences curated in CARD (note: this excludes resistance via mutation as references in protein variant models are often wild-type, sensitive sequences).

Prevalence: protein overexpression model (view sequences)

SpeciesNCBI ChromosomeNCBI PlasmidNCBI WGS
Acinetobacter baumannii0%0%0.02%
Acinetobacter nosocomialis0%0%1.1%
Enterobacter cloacae0%0%0%
Morganella morganii0%0%0%
Providencia rettgeri0%0%0%
Pseudomonas aeruginosa96.93%0%98.83%
Pseudomonas fluorescens3.85%0%0%
Serratia marcescens0%0%0.18%
Stenotrophomonas maltophilia0%0%0.53%
Show Perfect Only

Detection Models

Model Type: protein overexpression model

Model Definition: This model detects protein overexpression based on the presence of mutations. The detection of the protein without an associated mutation indicates that the protein is likely to be expressed at low or basal levels. The detection of the protein with the mutation indicates that the protein is likely overexpressed. This model reflects how certain proteins are functional with and without mutations. For example, efflux pump subunits and regulators are functional with mutations and without mutations. Without mutations, efflux pump subunits and regulators are usually expressed at a low level. When an efflux pump regulator has a mutation, it can cause the overexpression of the efflux pump it is responsible for regulating, leading to resistance to specific drugs. Protein overexpression models have two parameters: a curated BLASTP cutoff, and a curated set of mutations (single resistance variants, frameshift mutations, indels, etc.) shown clinically to confer resistance. This model type is a combination of the protein homolog and protein variant model. A detected hit can be categorized as Perfect, Strict, or Loose with no mutation(s) or as Strict or Loose with mutation(s).


  • discovered in clinical, agricultural, or environmental isolates
  • discovered via laboratory selection experiments

Bit-score Cut-off (blastP): 400

PMID: 27060003G71E S209R
PMID: 27412168R97G A186T

>gb|AAG07108.1|+|nalC [Pseudomonas aeruginosa PAO1]

>gb|AE004091.2|+|4166518-4167159|nalC [Pseudomonas aeruginosa PAO1]