A disorder to order transition accompanies catalysis in retinaldehyde dehydrogenase type II.
Retinaldehyde dehydrogenase II (RalDH2) converts retinal to the transcriptional regulator retinoic acid in the developing embryo. The x-ray structure of the enzyme revealed an important structural difference between this protein and other aldehyde dehydrogenases of the same enzyme superfamily; a 20-amino acid span in the substrate access channel in retinaldehyde dehydrogenase II is disordered, whereas in other aldehyde dehydrogenases this region forms a well defined wall of the substrate access channel. We asked whether this disordered loop might order during the course of catalysis and provide a means for an enzyme that requires a large substrate access channel to restrict access to the catalytic machinery by smaller compounds that might potentially enter the active site and be metabolized. Our experiments, a combination of kinetic, spectroscopic, and crystallographic techniques, suggest that a disorder to order transition is linked to catalytic activity.
Bordelon
Tee
T
Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Montegudo
Sarah K
SK
Pakhomova
Svetlana
S
Oldham
Michael L
ML
Newcomer
Marcia E
ME
D000445:Aldehyde Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009243:NAD / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D050697:Retinal Dehydrogenase; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013379:Substrate Specificity; D013997:Time Factors; D014158:Transcription, Genetic; D014212:Tretinoin / Q000737:chemistry; D014965:X-Rays
D009243:NAD; C033223:polyhistidine; D006639:Histidine; D014212:Tretinoin; D000445:Aldehyde Oxidoreductases; D050697:Retinal Dehydrogenase