Complete Biosynthetic Pathway of the C₅₀Carotenoid Bacterioruberin from Lycopene in the Extremely Halophilic Archaeon Haloarcula japonica

Abstract

Haloarcula japonica, an extremely halophilic archaeon that requires high concentrations of NaCl for growth, accumulates the C 50 carotenoid bacterioruberin (BR). By homology analysis, a gene cluster, including c0507, c0506, and c0505, was found and predicted to be involved in the synthesis of bacterioruberin. To elucidate the function of the encoded enzymes, we constructed Ha. japonica mutants of these genes and analyzed carotenoids produced by the mutants. Our research showed that c0507, c0506, and c0505 encoded a carotenoid 3,4-desaturase (CrtD), a bifunctional lycopene elongase and 1,2-hydratase (LyeJ), and a C 50 carotenoid 2؆,3؆-hydratase (CruF), respectively. The above three carotenoid biosynthetic enzymes catalyze the reactions that convert lycopene to bacterioruberin in Ha. japonica. This is the first identification of functional CrtD and CruF in archaea and elucidation of the complete biosynthetic pathway of bacterioruberin from lycopene. IMPORTANCEHaloarcula japonica, an extremely halophilic archaeon, accumulates the C 50 carotenoid bacterioruberin (BR). In this study, we have identified three BR biosynthetic enzymes and have elucidated their functions. Among them, two enzymes were found in an archaeon for the first time. Our results revealed the biosynthetic pathway responsible for production of BR in Ha. japonica and provide a basis for investigating carotenoid biosynthetic pathways in other extremely halophilic archaea. Elucidation of the carotenoid biosynthetic pathway in Ha. japonica may also prove useful for producing the C 50 carotenoid BR efficiently by employing genetically modified haloarchaeal strains.

Characterization of a bacterioruberin‐producing Haloarchaea isolated from the marshlands of the Odiel river in the southwest of Spain

“…The biosynthetic pathway for bacterioruberin proceeds from lycopene through a pathway only recently elucidated in the halophilic archaeon Haloarcula japonica, which involves the enzymes 3,4‐desarutrase (CrtD), lycopene elongase and 1,2‐hydratase (LyeJ) and C50 carotenoid 2″, 3″‐hydratase (CruF). Ortologous to some of these genes have been found in the genome of other related archaea .…”

Pink‐ and orange‐pigmented Planctomycetes produce saproxanthin‐type carotenoids including a rare C 45 carotenoid

“…). The responsible enzyme might be a homologue of the lycopene elongase LyeJ, which was identified in the bacterioruberin pathway of the archaeon Haloarcula japonica (Yang et al ., ). As the natural substrate of LyeJ is lycopene, the exact order in which elongase, hydratase and cyclase catalyze modification reactions at the end group for ultimately yielding 2′‐isopentenylsaproxanthin remains to be elucidated.…”

Carotenoid profile produced by Bacillus licheniformis Rt4M10 isolated from grapevines grown in high altitude and their antioxidant activity

“…Identification of carotenoids was achieved by matching retention times and comparing UV-visible fine spectra with authentic standard. Due to the lack of bacterial standards for some carotenoids, these compounds were tentatively identified by retention factor, the localisation of the maximum absorption wavelength (k max ) and degree of spectral vibrational fine structure (Table 1) according to various researchers (Weber et al, 2007;Mandelli et al, 2012;Steiger et al, 2012;Aschoff et al, 2015;Yang et al, 2015). Standard curves for the quantification of carotenoids were acquired by plotting amount (ng) against area obtained by triplicate according to the peak area ratios with b-apo-8 0 -carotenal.…”