Dataset Information

Carotenoid ?-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.

ABSTRACT: Marine bacteria belonging to genera Paracoccus and Brevundimonas of the ?-Proteobacteria class can produce C??-type dicyclic carotenoids containing two ?-end groups (? rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid ?-ring 4(4')-ketolase (4(4')-oxygenase; CrtW) and hydroxylated by carotenoid ?-ring 3(3')-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid ?-ring 2(2')-hydroxylase (CrtG). This review focuses on these carotenoid ?-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., ?-ring(s)-2(2')-hydroxylated carotenoids).

SUBMITTER: Misawa N

PROVIDER: S-EPMC3111180 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Carotenoid β-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.

Misawa Norihiko N

Marine drugs 20110506 5

Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C₄₀-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4')-ketolase (4(4')-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3')-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for c ...[more]

PMID: 21673887

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Project description:The siderophore synthetic system in Shewanella species is able to synthesize dozens of macrocyclic siderophores in vitro with synthetic precursors. In vivo, however, although three siderophores are produced naturally in Shewanella algae B516, which carries a lysine decarboxylase (AvbA) specific for siderophore synthesis, only one siderophore can be detected from many other Shewanella species. In this study, we examined a siderophore-overproducing mutant of Shewanella oneidensis which lacks an AvbA counterpart, and we found that it can also produce these three siderophores. We identified both SpeC and SpeF as promiscuous decarboxylases for both lysine and ornithine to synthesize the siderophore precursors cadaverine and putrescine, respectively. Intriguingly, putrescine is mainly synthesized from arginine through an arginine decarboxylation pathway in a constitutive manner, not liable to the concentrations of iron and siderophores. Our results provide further evidence that the substrate availability plays a determining role in siderophore production. Furthermore, we provide evidence to suggest that under iron starvation conditions, cells allocate more putrescine for siderophore biosynthesis by downregulating the expression of the enzyme that transforms putrescine into spermidine. Overall, this study provides another example of the great flexibility of bacterial metabolism that is honed by evolution to better fit living environments of these bacteria.IMPORTANCE The simultaneous production of multiple siderophores is considered a general strategy for microorganisms to rapidly adapt to their ever-changing environments. In this study, we show that some Shewanella spp. may downscale their capability for siderophore synthesis to facilitate adaptation. Although S. oneidensis lacks an enzyme specifically synthesizing cadaverine, it can produce it by using promiscuous ornithine decarboxylases. Despite this ability, this bacterium predominately produces the primary siderophore while restraining the production of secondary siderophores by regulating substrate availability. In addition to using the arginine decarboxylase (ADC) pathway for putrescine synthesis, cells optimize the putrescine pool for siderophore production. Our work provides an insight into the coordinated synthesis of multiple siderophores by harnessing promiscuous enzymes in bacteria and underscores the importance of substrate pools for the biosynthesis of natural products.

Dataset Information

Carotenoid ?-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.

Publications

Carotenoid β-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.

Similar Datasets

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