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.

Citation

Tee Bordelon, Sarah K Montegudo, Svetlana Pakhomova, Michael L Oldham, Marcia E Newcomer. A disorder to order transition accompanies catalysis in retinaldehyde dehydrogenase type II. The Journal of biological chemistry. 2004 Oct 08;279(41):43085-91

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PMID: 15299009

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