Characterization of regioisomeric diterpenoid tails in bacteriochlorophylls produced by geranylgeranyl reductase from Halorhodospira halochloris and Blastochloris viridis

Geranylgeranyl reductase (GGR) encoded by the bchP gene catalyzes the reductions of three unsaturated C = C double bonds (C6 = C7, C10 = C11, and C14 = C15) in a geranylgeranyl (GG) group of the esterifying moiety in 17-propionate residue of bacteriochlorophyll (BChl) molecules. It was recently repo...

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Bibliographic Details
Published in:Photosynthesis research 2022-10, Vol.154 (1), p.1-12
Main Authors: Hirose, Mitsuaki, Tsukatani, Yusuke, Harada, Jiro, Tamiaki, Hitoshi
Format: Article
Language:English
Subjects:
Bacteriochlorophyll
Biochemistry
Biomedical and Life Sciences
Chemical properties
Diterpenes
Enzymes
Hydrogenation
Life Sciences
Olefins
Original Article
Phototrophic bacteria
Plant Genetics and Genomics
Plant Physiology
Plant Sciences
Propionic acid
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Summary:Geranylgeranyl reductase (GGR) encoded by the bchP gene catalyzes the reductions of three unsaturated C = C double bonds (C6 = C7, C10 = C11, and C14 = C15) in a geranylgeranyl (GG) group of the esterifying moiety in 17-propionate residue of bacteriochlorophyll (BChl) molecules. It was recently reported that GGR in Halorhodospira halochloris potentially catalyzes two hydrogenations, yielding BChl with a tetrahydrogeranylgeranyl (THGG) tail. Furthermore, its engineered GGR, in which N -terminal insertion peptides characteristic for H. halochloris were deleted, performed single hydrogenation, producing BChl with a dihydrogeranylgeranyl (DHGG) tail. In some of these enzymatic reactions, it remained unclear in which order the C = C double bond in a GG group was first reduced. In this study, we demonstrated that the (variant) GGR from H. halochloris catalyzed an initial reduction of the C6 = C7 double bond to yield a 6,7-DHGG tail. The intact GGR of H. halochloris catalyzed the further hydrogenation of the C14 = C15 double bonds to give a 6,7,14,15-THGG group, whereas deleting the characteristic peptide region from the GGR suppressed the C14 = C15 reduction. We also verified that in a model bacterium, Blastochloris viridis producing standard BChl- b , the reduction of a GG to phytyl group occurred via 10,11-DHGG and 6,7,10,11-THGG. The high-performance liquid chromatographic elution profiles of BChls- a / b employed in this study are essential for identifying the regioisomeric diterpenoid tails in the BChls of phototrophic bacteria distributed in nature and elucidating GGR enzymatic reactions.
ISSN:0166-8595
1573-5079
DOI:10.1007/s11120-022-00938-3