Signature motifs identify an Acinetobacter Cif virulence factor with epoxide hydrolase activity.
Endocytic recycling of the cystic fibrosis transmembrane conductance regulator (CFTR) is blocked by the CFTR inhibitory factor (Cif). Originally discovered in Pseudomonas aeruginosa, Cif is a secreted epoxide hydrolase that is transcriptionally regulated by CifR, an epoxide-sensitive repressor. In this report, we investigate a homologous protein found in strains of the emerging nosocomial pathogens Acinetobacter nosocomialis and Acinetobacter baumannii ("aCif"). Like Cif, aCif is an epoxide hydrolase that carries an N-terminal secretion signal and can be purified from culture supernatants. When applied directly to polarized airway epithelial cells, mature aCif triggers a reduction in CFTR abundance at the apical membrane. Biochemical and crystallographic studies reveal a dimeric assembly with a stereochemically conserved active site, confirming our motif-based identification of candidate Cif-like pathogenic EH sequences. Furthermore, cif expression is transcriptionally repressed by a CifR homolog ("aCifR") and is induced in the presence of epoxides. Overall, this Acinetobacter protein recapitulates the essential attributes of the Pseudomonas Cif system and thus may facilitate airway colonization in nosocomial lung infections.
From the Departments of Biochemistry and.
Christopher D
CD
Bahl
Kelli L
KL
Hvorecny
Andrew A
AA
Bridges
Alicia E
AE
Ballok
Jennifer M
JM
Bomberger
Kyle C
KC
Cady
George A
GA
O'Toole
Dean R
DR
Madden
D000150:Acinetobacter / Q000201:enzymology* / Q000235:genetics; D040981:Acinetobacter baumannii / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D004705:Endocytosis; D004851:Epoxide Hydrolases / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014158:Transcription, Genetic; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D037521:Virulence Factors; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D004851:Epoxide Hydrolases
Airway Infection; CFTR; Enzyme Catalysis; Epoxide Hydrolase; Gene Transcription; Mutagenesis Site Specific; Protein Conformation; Substrate Specificity; X-ray Crystallography