title: Chalcone isomerase family and fold: no longer unique to plants.
abstract: Chalcone isomerase, an enzyme in the isoflavonoid pathway in plants, catalyzes the cyclization of chalcone into (2S)-naringenin. Chalcone isomerase sequence family and three-dimensional fold appeared to be unique to plants and has been proposed as a plant-specific gene marker. Using sensitive methods of sequence comparison and fold recognition, we have identified genes homologous to chalcone isomerase in all completely sequenced fungi, in slime molds, and in many gammaproteobacteria. The residues directly involved in the enzyme's catalytic function are among the best conserved across species, indicating that the newly discovered homologs are enzymatically active. At the same time, fungal and bacterial species that have chalcone isomerase-like genes tend to lack the orthologs of the upstream enzyme chalcone synthase, suggesting a novel variation of the pathway in these species.
authors.affiliation: Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA. arm@stowers-institute.org
authors.forename: Michael
authors.initials: M
authors.lastname: Gensheimer
authors.forename: Arcady
authors.initials: A
authors.lastname: Mushegian
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D005658:Fungi / Q000201:enzymology*; D020563:Gammaproteobacteria / Q000201:enzymology*; D019753:Intramolecular Lyases / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology*; D017510:Protein Folding; D017386:Sequence Homology, Amino Acid
chemical_list: D019753:Intramolecular Lyases; C019865:chalcone isomerase