Absence of the cbb₃ Terminal Oxidase Reveals an Active Oxygen-Dependent Cyclase Involved in Bacteriochlorophyll Biosynthesis in Rhodobacter sphaeroides

Chen, Guangyu E, Canniffe, Daniel P ORCID: 0000-0002-5022-0437, Martin, Elizabeth C and Hunter, C Neil (2016) Absence of the cbb₃ Terminal Oxidase Reveals an Active Oxygen-Dependent Cyclase Involved in Bacteriochlorophyll Biosynthesis in Rhodobacter sphaeroides JOURNAL OF BACTERIOLOGY, 198 (15). pp. 2056-2063. ISSN 0021-9193, 1098-5530

Text Absence of the cbb3 Terminal Oxidase Reveals an Active Oxygen-Dependent Cyclase Involved in Bacteriochlorophyll Biosynthesis in Rhodobacter sphaeroides.pdf - Published version Download (1MB)

Abstract

The characteristic green color associated with chlorophyll pigments results from the formation of an isocyclic fifth ring on the tetrapyrrole macrocycle during the biosynthesis of these important molecules. This reaction is catalyzed by two unrelated cyclase enzymes employing different chemistries. Oxygenic phototrophs such as plants and cyanobacteria utilize an oxygen-dependent enzyme, the major component of which is a diiron protein named AcsF, while BchE, an oxygen-sensitive [4Fe-4S] cluster protein, dominates in phototrophs inhabiting anoxic environments, such as the purple phototrophic bacterium Rhodobacter sphaeroides.We identify a potential acsF in this organism and assay for activity of the encoded protein in a strain lacking bchE under various aeration regimes. Initially, cells lacking bchE did not demonstrate AcsF activity under any condition tested. However, on removal of a gene encoding a subunit of the cbb3-type respiratory terminal oxidase, cells cultured under regimes ranging from oxic to micro-oxic exhibited cyclase activity, confirming the activity of the oxygen-dependent enzyme in this model organism. Potential reasons for the utilization of an oxygen-dependent enzyme in anoxygenic phototrophs are discussed.

Item Type:	Article
Uncontrolled Keywords:	Rhodobacter sphaeroides, Bacteriochlorophylls, Electron Transport Complex IV, Gene Expression Regulation, Bacterial, Gene Expression Regulation, Enzymologic, Gene Deletion, Molecular Structure, Amino Acid Sequence, Mutation
Depositing User:	Symplectic Admin
Date Deposited:	17 Jan 2019 08:24
Last Modified:	16 Jun 2026 14:21
DOI:	10.1128/JB.00121-16
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3031334
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