| First Author | Palczewski G | Year | 2014 |
| Journal | FASEB J | Volume | 28 |
| Issue | 10 | Pages | 4457-69 |
| PubMed ID | 25002123 | Mgi Jnum | J:217571 |
| Mgi Id | MGI:5614547 | Doi | 10.1096/fj.14-252411 |
| Citation | Palczewski G, et al. (2014) Evidence for compartmentalization of mammalian carotenoid metabolism. FASEB J 28(10):4457-69 |
| abstractText | The critical role of retinoids (vitamin A and its derivatives) for vision, reproduction, and survival has been well established. Vitamin A is produced from dietary carotenoids such as beta-carotene by centric cleavage via the enzyme BCO1. The biochemical and molecular identification of a second structurally related beta-carotene metabolizing enzyme, BCO2, has led to a prolonged debate about its relevance in vitamin A biology. While BCO1 cleaves provitamin A carotenoids, BCO2 is more promiscuous and also metabolizes nonprovitamin A carotenoids such as zeaxanthin into long-chain apo-carotenoids. Herein we demonstrate, in cell lines, that human BCO2 is associated with the inner mitochondrial membrane. Different human BCO2 isoforms possess cleavable N-terminal leader sequences critical for mitochondrial import. Subfractionation of murine hepatic mitochondria confirmed the localization of BCO2 to the inner mitochondrial membrane. Studies in BCO2-knockout mice revealed that zeaxanthin accumulates in the inner mitochondrial membrane; in contrast, beta-carotene is retained predominantly in the cytoplasm. Thus, we provide evidence for a compartmentalization of carotenoid metabolism that prevents competition between BCO1 and BCO2 for the provitamin and the production of noncanonical beta-carotene metabolites. |
