Conversion of the lycopene monocyclase of Myxococcus xanthus into a bicyclase

Iniesta, Antonio A.; Cervantes, María; Murillo, Francisco J.

doi:10.1007/s00253-008-1481-7

Cited by 14 publications

(13 citation statements)

References 48 publications

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“…A heterodimeric enzyme composed of CrtYc and CrtYd likely carries out these serial cyclizations, much like Myxococcus xanthus, ␤-cyclase genes [36% and 33% identity, trihelical transmembrane topology, PxE(E/D) catalytic motif] ( Fig. S2) (34)(35)(36)(37). The symmetric cleavage of ␤-carotene by a ␤-carotene oxygenase, Blh, would then form retinal (step 6).…”

Section: Resultsmentioning

confidence: 99%

acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively Synthesized Retinal

Dwulit-Smith

Hamilton

Stevenson

et al. 2018

Appl Environ Microbiol

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Freshwater lakes harbor complex microbial communities, but these ecosystems are often dominated by acIActinobacteria. Members of this cosmopolitan lineage are proposed to bolster heterotrophic growth using phototrophy because their genomes encode actino-opsins (actR). This model has been difficult to validate experimentally because acIActinobacteriaare not consistently culturable. Based primarily on genomes from single cells and metagenomes, we provide a detailed biosynthetic route for members of acI clades A and B to synthesize retinal and its carotenoid precursors. Consequently, acI cells should be able to natively assemble light-driven actinorhodopsins (holo-ActR) to pump protons, unlike many bacteria that encode opsins but may need to exogenously obtain retinal because they lack retinal machinery. Moreover, we show that all acI clades contain genes for a secondary branch of the carotenoid pathway, implying synthesis of a complex carotenoid. Transcription analysis of acIActinobacteriain a eutrophic lake shows that all retinal and carotenoid pathway operons are transcribed and thatactRis among the most highly transcribed of all acI genes. Furthermore, heterologous expression of acI retinal pathway genes showed that lycopene, retinal, and ActR can be made using the genes encoded in these organisms. Model cells producing ActR and the key acI retinal-producing β-carotene oxygenase formed holo-ActR and acidified solution during illumination. Taken together, our results prove that acIActinobacteriacontaining both ActR and acI retinal production machinery have the capacity to natively synthesize a green light-dependent outward proton-pumping rhodopsin.IMPORTANCEMicrobes play critical roles in determining the quality of freshwater ecosystems, which are vital to human civilization. Because acIActinobacteriaare ubiquitous and abundant in freshwater lakes, clarifying their ecophysiology is a major step in determining the contributions that they make to nitrogen and carbon cycling. Without accurate knowledge of these cycles, freshwater systems cannot be incorporated into climate change models, ecosystem imbalances cannot be predicted, and policy for service disruption cannot be planned. Our work fills major gaps in microbial light utilization, secondary metabolite production, and energy cycling in freshwater habitats.

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Section: Resultsmentioning

confidence: 99%

acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively Synthesized Retinal

Dwulit-Smith

Hamilton

Stevenson

et al. 2018

Appl Environ Microbiol

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“…Carotenoids are a large class of yellow, orange, and red lipophilic molecules synthesized by all photosynthetic organisms (Cuttriss et al, 2011), aphids (Moran and Jarvik, 2010), and various bacteria and fungi (Velayos et al, 2000;Iniesta et al, 2008). In plants, carotenoids play multiple roles, such as photosynthetic light harvesting and protection against light and heat stress , and as precursors to hormones that mediate stress and developmental signaling (Auldridge et al, 2006;Messing et al, 2010;Walter et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Plastid Localization of the Key Carotenoid Enzyme Phytoene Synthase Is Altered by Isozyme, Allelic Variation, and Activity

et al. 2012

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Plant carotenoids have unique physiological roles related to specific plastid suborganellar locations. Carotenoid metabolic engineering could enhance plant adaptation to climate change and improve food security and nutritional value. However, lack of fundamental knowledge on carotenoid pathway localization limits targeted engineering. Phytoene synthase (PSY), a major rate-controlling carotenoid enzyme, is represented by multiple isozymes residing at unknown plastid sites. In maize (Zea mays), the three isozymes were transiently expressed and found either in plastoglobuli or in stroma and thylakoid membranes. PSY1, with one to two residue modifications of naturally occurring functional variants, exhibited altered localization, associated with distorted plastid shape and formation of a fibril phenotype. Mutating the active site of the enzyme reversed this phenotype. Discovery of differential PSY locations, linked with activity and isozyme type, advances the engineering potential for modifying carotenoid biosynthesis.

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“…A heterodimeric enzyme composed of acI-CrtYc and acI-CrtYd likely carries out these serial cyclizations, much like Myxococcus xanthus β-cyclase genes (36% and 33% identity, trihelical transmembrane topology, PxE(E/D) catalytic motif) (Fig. S2) (29-32). The symmetric cleavage of β-carotene by a β-carotene oxygenase, acI-Blh, would then form retinal (Step 6).…”

Section: Resultsmentioning

confidence: 99%

“…2, 3, 4). Homologs of these gene products were found in Myxococcus xanthus and confirmed to synthesize a mix of γ-carotene and β-carotene (29). Therefore, we propose that acI can also synthesize these chromophores.…”

Section: Discussionmentioning

confidence: 99%

acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively-synthesized Retinal

Dwulit-Smith

Hamilton

Stevenson

et al. 2018

Preprint

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18Freshwater lakes harbor complex microbial communities, but these ecosystems are often dominated by acI 19Actinobacteria from three clades (acI-A, acI-B, acI-C). Members of this cosmopolitan lineage are proposed 20 to bolster heterotrophic growth using phototrophy because their genomes encode actino-opsins (actR). 21This model has been difficult to experimentally validate because acI are not consistently culturable. In this 22 study, using genomes from single cells and metagenomes, we provide a detailed biosynthetic route for 23 many acI-A and -B members to synthesize retinal and its carotenoid precursors. Accordingly, these acI 24 should be able to natively assemble light-driven actinorhodopsins (holo-ActR) to pump protons, in contrast 25 to acI-C members and other bacteria that encode opsins but lack retinal-production machinery. Moreover, 26we show that all acI clades contain genes for a complex carotenoid pathway that starts with retinal 27 precursors. Transcription analysis of acI in a eutrophic lake shows that all retinal and carotenoid pathway 28 operons are transcribed and that actR is among the most highly-transcribed of all acI genes. Furthermore, 29 heterologous expression of retinal pathway genes shows that lycopene, retinal, and ActR can be made. 30Model cells producing ActR and the key acI retinal-producing β-carotene oxygenase formed acI-holo-ActR 31 and acidified solution during illumination. Our results prove that acI containing both ActR and retinal-32 production enzymes have the capacity to natively synthesize a green light-dependent outward proton-33 pumping rhodopsin. 35 IMPORTANCE 36Microbes play critical roles in determining the quality of freshwater ecosystems that are vital to human 37 civilization. Because acI Actinobacteria are ubiquitous and abundant in freshwater lakes, clarifying their 38 ecophysiology is a major step in determining the contributions that they make to nitrogen and carbon 39 cycling. Without accurate knowledge of these cycles, freshwater systems cannot be incorporated into 40 climate change models, ecosystem imbalances cannot be predicted, and policy for service disruption 41 cannot be planned. Our work fills major gaps in microbial light utilization, secondary metabolite production, 42and energy cycling in freshwater habitats.

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Conversion of the lycopene monocyclase of Myxococcus xanthus into a bicyclase

Cited by 14 publications

References 48 publications

acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively Synthesized Retinal

acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively Synthesized Retinal

Plastid Localization of the Key Carotenoid Enzyme Phytoene Synthase Is Altered by Isozyme, Allelic Variation, and Activity

acI Actinobacteria Assemble a Functional Actinorhodopsin with Natively-synthesized Retinal

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