Filling the Gap in Vitamin A Research

Abstract

Vitamin A and its derivatives (retinoids) are essential components in vision; they contribute to pattern forma- tion during development and exert multiple effects on cell differentiation with important clinical implications. It has been known for 50 years that the key step in the formation of vitaminAis the oxidative cleavage of -car- otene; however, this enzymatic step has resisted molec- ular analysis. A novel approach enabled us to clone and identify a -carotene dioxygenase from Drosophila melanogaster, expressing it into the background of a -carotene (provitamin A)-synthesizing and -accumulat- ing Escherichia coli strain. The carotene-cleaving en- zyme, identified here for the first time on the molecular level, is the basis of the numerous branches of vitamin A action and links plant and animal carotene metabolism.