Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/119242
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- Title
- BchJ and BchM interact in a 1 : 1 ratio with the magnesium chelatase BchH subunit of Rhodobacter capsulatus
- Related
- Febs journal, Vol. 277, No. 22 (2010), p.4709-4721
- DOI
- 10.1111/j.1742-4658.2010.07877.x
- Publisher
- Wiley-Blackwell
- Date
- 2010
- FoR/RFCD Code(s)
-
110100 Medical Biochemistry and Metabolomics
060100 Biochemistry and Cell Biology
- Author/Creator
- Sawicki, Artur
- Author/Creator
- Willows, Robert D
- Description
- Substrate channeling between the enzymatic steps in the (bacterio)chlorophyll biosynthetic pathway catalyzed by magnesium chelatase (BchI/ChlI, BchD/ChlD and BchH/ChlH subunits) and S-adenosyl-l-methionine:magnesium-protoporphyrin IX O-methyltransferase (BchM/ChlM) has been suggested. This involves delivery of magnesium-protoporphyrin IX from the BchH/ChlH subunit of magnesium chelatase to BchM/ChlM. Stimulation of BchM/ChlM activity by BchH/ChlH has previously been shown, and physical interaction of the two proteins has been demonstrated. In plants and cyanobacteria, there is an added layer of complexity, as Gun4 serves as a porphyrin (protoporphyrin IX and magnesium-protoporphyrin IX) carrier, but this protein does not exist in anoxygenic photosynthetic bacteria. BchJ may play a similar role to Gun4 in Rhodobacter, as it has no currently assigned function in the established pathway. Purified recombinant Rhodobacter capsulatus BchJ and BchM were found to cause a shift in the equilibrium amount of Mg-protoporphyrin IX formed in a magnesium chelatase assay. Analysis of this shift revealed that it was always in a 1 : 1 ratio with either of these proteins and the BchH subunit of the magnesium chelatase. The establishment of the new equilibrium was faster with BchM than with BchJ in a coupled magnesium chelatase assay. BchJ bound magnesium-protoporphyrin IX or formed a ternary complex with BchH and magnesium-protoporphyrin IX. These results suggest that BchJ may play a role as a general magnesium porphyrin carrier, similar to one of the roles of GUN4 in oxygenic organisms.
- Description
- 13 page(s)
- Subject Keyword
- 110100 Medical Biochemistry and Metabolomics
- Subject Keyword
- 060100 Biochemistry and Cell Biology
- Subject Keyword
- bacteriochlorophyll biosynthesis
- Subject Keyword
- BchJ
- Subject Keyword
- BchM
- Subject Keyword
- magnesium chelatase
- Subject Keyword
- O-methyltransferase
- Resource Type
- journal article
- Organisation
- Macquarie University. Dept. of Chemistry and Biomolecular Sciences
- Identifier
- http://hdl.handle.net/1959.14/119242
- Identifier
- ISSN:1742-464X
- Identifier
- mq-rm-2010003622
- Language
- eng
- Reviewed
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