Accession ARO:3000149
DefinitionAn enzyme that confers resistance to fosfomycin in Serratia marcescens by breaking the epoxide ring of the molecule. It depends on the cofactors Manganese (II) and Potassium and uses Glutathione (GSH) as the nucleophilic molecule. In Pseudomonas aeruginosa, FosA catalyzes the conjugation of glutathione to carbon-1 of fosfomycin, rendering it ineffective as an antibacterial drug.
AMR Gene Familyfosfomycin thiol transferase
Drug Classfosfomycin
Resistance Mechanismantibiotic inactivation
ResistomesPseudomonas aeruginosag+wgs, Pseudomonas fluorescenswgs
Classification12 ontology terms | Show
Parent Term(s)2 ontology terms | Show
+ confers_resistance_to_antibiotic fosfomycin [Drug Class]
+ fosfomycin thiol transferase [AMR Gene Family]

Pakhomova S, et al. 2004. Protein Sci 13(5): 1260-1265. Structure of fosfomycin resistance protein FosA from transposon Tn2921. (PMID 15075406)

Beharry Z, et al. 2005. J. Biol. Chem. 280(18):17786-91 Functional analysis of active site residues of the fosfomycin resistance enzyme FosA from Pseudomonas aeruginosa. (PMID 15741169)


Prevalence of FosA among the sequenced genomes, plasmids, and whole-genome shotgun assemblies available at NCBI for 85 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 homolog model (view sequences)

SpeciesNCBI ChromosomeNCBI PlasmidNCBI WGS
Pseudomonas aeruginosa97.66%0%98.54%
Pseudomonas fluorescens22.22%0%92.06%
Pseudomonas putida0%0%2.5%
Show Perfect Only

Detection Models

Model Type: protein homolog model

Model Definition: The protein homolog model is an AMR detection model. Protein homolog models detect a protein sequence based on its similarity to a curated reference sequence. A protein homolog model has only one parameter: a curated BLASTP bitscore cutoff for determining the strength of a match. Protein homolog model matches to reference sequences are categorized on three criteria: perfect, strict and loose. A perfect match is 100% identical to the reference sequence along its entire length; a strict match is not identical but the bitscore of the matched sequence is greater than the curated BLASTP bitscore cutoff. Loose matches are other sequences with a match bitscore less than the curated BLASTP bitscore.

Bit-score Cut-off (blastP): 200

>gb|AAG04518.1|+|fosA [Pseudomonas aeruginosa PAO1]

>gb|AE004091.2|+|1221691-1222098|fosA [Pseudomonas aeruginosa PAO1]