Mg-protoporphyrin IX monomethyl ester cyclase from Rhodobacter capsulatus: radical SAM-dependent synthesis of the isocyclic ring of bacteriochlorophylls
- ,
- Milan Wiesselmann,
- Stefanie Hebecker,
- José M Borrero-de Acuña,
- Manfred Nimtz,
- Lothar Jänsch
- Institute of Microbiology, Technische Universität Braunschweig,
- Cellular Proteome Research, Helmholtz Centre for Infection Research,
- Cellular Proteome Research, Helmholtz Centre for Infection Research,,
- Braunschweig Centre of Integrated Systems Biology,
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Journal Article
Article
Peer-reviewAbstract
During bacteriochlorophyll a biosynthesis, the oxygen-independent conversion of Mg-protoporphyrin IX monomethyl ester (Mg-PME) to protochlorophyllide (Pchlide) is catalyzed by the anaerobic Mg-PME cyclase termed BchE. Bioinformatics analyses in combination with pigment studies of cobalamin-requiring Rhodobacter capsulatus mutants indicated an unusual radical S-adenosylmethionine (SAM) and cobalamin-dependent BchE catalysis. However, in vitro biosynthesis of the isocyclic ring moiety of bacteriochlorophyll using purified recombinant BchE has never been demonstrated. We established a spectroscopic in vitro activity assay which was subsequently validated by HPLC analyses and H218O isotope label transfer onto the carbonyl-group (C-131-oxo) of the isocyclic ring of Pchlide. The reaction product was further converted to chlorophyllide in the presence of light-dependent Pchlide reductase.
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Scholarship:
Journal Article
Article
Peer-reviewOriginal language
American EnglishJournal (Volume, Issue Number)
Biochemical Journal (Volume 477)Publication milestones
- Published - 12/2020
Publication status
Published - 12/2020
Publication IDs
- Scopus: 85098472201
- PubMed: 33211085
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