Elucidation of a Carotenoid Biosynthesis Gene Cluster Encoding a Novel Enzyme, 2,2′-β-Hydroxylase, from Brevundimonas sp. Strain SD212 and Combinatorial Biosynthesis of New or Rare Xanthophylls

Abstract

A carotenoid biosynthesis gene cluster mediating the production of 2-hydroxyastaxanthin was isolated from the marine bacterium Brevundimonas sp. strain SD212 by using a common crtI sequence as the probe DNA. A sequence analysis revealed this cluster to contain 12 open reading frames (ORFs), including the 7 known genes, crtW, crtY, crtI, crtB, crtE, idi, and crtZ. The individual ORFs were functionally analyzed by complementation studies using Escherichia coli that accumulated various carotenoid precursors due to the presence of other bacterial crt genes. In addition to functionally identifying the known crt genes, we found that one (ORF11, named crtG) coded for a novel enzyme, carotenoid 2,2-␤-hydroxylase, which showed intriguingly partial homology with animal sterol-C5-desaturase. When this crtG gene was introduced into E. coli accumulating zeaxanthin and canthaxanthin, the resulting transformants produced their 2-hydroxylated and 2,2-dihydroxylated products which were structurally novel or rare xanthophylls, as determined by their nuclear magnetic resonance and high-performance liquid chromatography/photodiode array detector/atmospheric pressure chemical ionization mass spectrometry spectral data. The new carotenoid produced was suggested to have a strong inhibitory effect on lipid peroxidation.Carotenoid pigments, which are included in a majority of vegetables, a variety of fruits, and a certain part of edible fish and shellfish, have attracted strong attention due to their beneficial effects on human health, e.g., their very likely prevention of chronic diseases such as cancer, cardiovascular ailments, and age-related macular degeneration (7,12,27,36). A number of studies on carotenoids in relation to their health benefits, ranging from basic studies using experimental animals to clinical and epidemiological studies, have revealed that each carotenoid has characteristic individuality. For example, recent epidemiological studies have shown that ␤-cryptoxanthin (3-hydroxy-␤-carotene), among dietary carotenoids, is associated with a reduced risk of lung cancer (24, 56), whereas supplemental ␤-carotene has been observed to have either no effect or even a harmful effect on lung cancer risk (2, 24). Epidemiological and clinical studies have also shown that only lycopene, among dietary carotenoids, was inversely associated with prostate cancer risk (16, 51). Supplemental lutein and zeaxanthin are thought to protect against the development or progression of age-related macular degeneration and other eye diseases from the results of many studies (28,45). Astaxanthin has been shown to inhibit the oxidation of low-density lipoprotein (20).Xanthophylls are modified carotenes with various oxygencontaining functional groups, which constitute a major part of structurally and functionally diverse carotenoid pigments.More than 700 carotenoids have now been isolated from natural sources (8), and evaluating the pharmaceutical potential of various carotenoids with different structures could be an exciting field for medical resea...

A novel carotenoid 1,2-hydratase (CruF) from two species of the non-photosynthetic bacterium Deinococcus

“…A carotenoid 2,29-b-hydroxylase (CrtG) was detected in Brevundimonas sp. strain SD212 (Nishida et al, 2005). Recently, a CrtG was found in the carotenoid biosynthetic pathway of Thermosynechococcus elongatus strain BP-1; this was the first functional identification of CrtG in a cyanobacterium (Iwai et al, (Krubasik & Sandmann, 2000).…”

Differences in Carotenoid Composition among Hymenobacter and Related Strains Support a Tree-Like Model of Carotenoid Evolution

“…Carotenoids are particularly well-known scavengers of reactive oxygen species, such as singlet oxygen (21,35), and in humans contribute both to the maintenance of proper cell function and to disease prevention (21,27,34,35). Carotenoid biosynthesis has been well studied in many microorganisms (10,32), particularly regarding the creation of recombinant biosynthetic pathways leading to the production of novel pigments (29,41) with biotechnologically interesting properties, such as improved antioxidant activity (1,26). These approaches require the identification of novel biosynthetic enzymes having expanded substrate ranges and activities, the discovery of which requires a clear understanding of carotenoid diversity and distribution.…”

Pathway engineering of plants toward astaxanthin production

“…and Brevundimonas sp. (Lee and Kim 2006;Misawa et al 1995a;1995b;Nishida et al 2005;Tao et al 2006a). Their homologous genes have also been isolated from H. pluvialis (Kajiwara et al 1995;Linden 1999;Lotan and Hirschberg 1995).…”