Identification of a critical amino acid in the aryl hydrocarbon receptor.

TitleIdentification of a critical amino acid in the aryl hydrocarbon receptor.
Publication TypeJournal Article
Year of Publication2002
AuthorsAndreasen, EA, Tanguay, RL, Peterson, RE, Heideman, W
JournalJ Biol Chem
Date Published2002 Apr 12
KeywordsAmino Acid Sequence, Amino Acid Substitution, Amino Acids, Animals, Base Sequence, COS Cells, DNA Primers, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Oncorhynchus mykiss, Protein Conformation, Receptors, Aryl Hydrocarbon, Sequence Homology, Amino Acid

Two aryl hydrocarbon receptors (rtAHR2alpha and rtAHR2beta) have been identified in the rainbow trout (Oncorhynchus mykiss). These receptors share 98% amino acid identity, yet their functional properties differ. Both rtAHR2alpha and rtAHR2beta bind 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dimerize with rainbow trout ARNTb (rtARNTb), and recognize dioxin response elements in vitro. However, in a transient transfection assay the two proteins show differential ability to recognize enhancers, produce transactivation, and respond to TCDD. To identify the sequence differences that confer the functional differences between rtAHR2alpha and rtAHR2beta, we constructed chimeric rtAHRs, in which segments of one receptor form was replaced with the corresponding part from the other isoform. This approach progressively narrowed the region being examined to a single residue, corresponding to position 111 in rtAHR2beta. Altering this residue in rtAHR2beta from the lysine to glutamate found in rtAHR2alpha produced an rtAHR2beta with the properties of rtAHR2alpha. All other known AHRs resemble rtAHR2alpha and carry glutamate at this position, located at the N terminus of the PAS-A domain. We tested the effect of altering this glutamate in the human and zebrafish AHRs to lysine. This lysine substitution produced AHRs with transactivation properties that were similar to rtAHR2beta. These results identify a critical residue in AHR proteins that has an important impact on transactivation, enhancer site recognition, and regulation by ligand.

Alternate JournalJ. Biol. Chem.
PubMed ID11823471
Grant ListES 10820 / ES / NIEHS NIH HHS / United States
P30 ES 09090 / ES / NIEHS NIH HHS / United States