Open AccessFunctional analysis of γ‐carotene ketolase involved in the carotenoid biosynthesis of Deinococcus radiodurans
Author(s) -
Sun Zongtao,
Shen Shaochuan,
Tian Bing,
Wang Hu,
Xu Zhenjian,
Wang Liangyan,
Hua Yuejin
Publication year - 2009
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2009.01794.x
Subject(s) - deinococcus radiodurans , carotenoid , mutant , biosynthesis , carotene , wild type , biochemistry , antioxidant , biology , chemistry , gene , food science
Deinococcus radiodurans strain R1 synthesizes a unique ketocarotenoid product named deinoxanthin. The detailed steps involved in the biosynthesis of deinoxanthin remain unresolved. A carotene ketolase homologue encoded by dr0093 was inactivated by gene mutation to verify its function in the native host D. radiodurans . Analysis of the carotenoids in the resultant mutant R1ΔcrtO demonstrated that dr0093 encodes γ‐carotene ketolase (CrtO) catalysing the introduction of one keto group into the C‐4 position of γ‐carotene derivatives to form ketolated carotenoids. The mutant R1ΔcrtO became more sensitive to H 2 O 2 treatment than the wild‐type strain R1, indicating that the C‐4 keto group is important for the antioxidant activity of carotenoids in D. radiodurans . Carotenoid extracts from mutant R1ΔcrtO exhibited lower 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging activity than those from the wild‐type strain R1. The enhanced antioxidant ability of ketocarotenoids in D. radiodurans might be attributed to its extended conjugated double bonds and relative stability by the C‐4 keto group substitution.