Kinetic basis for linking the first two enzymes of chlorophyll biosynthesis

Shepherd, Mark and McLean, Samantha and Hunter, C. Neil (2005) Kinetic basis for linking the first two enzymes of chlorophyll biosynthesis. FEBS Journal, 272 (17). pp. 4532-4539. ISSN 1742464X. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Purified recombinant proteins from Synechocystis PCC6803 were used to show that the magnesium chelatase ChlH subunit stimulates magnesium protoporphyrin methyltransferase (ChlM) activity. Steady-state kinetics demonstrate that ChlH does not significantly alter the K(m) for the tetrapyrrole substrate. However, quenched-flow analysis reveals that ChlH dramatically accelerates the formation and breakdown of an intermediate in the catalytic cycle of ChlM. In light of the profound effect that ChlH has on the methyltransferase catalytic intermediate, the pre steady-state analysis in the current study suggests that ChlH is directly involved in the reaction chemistry. The kinetic coupling between the chelatase and methyltransferase has important implications for regulation of chlorophyll biosynthesis and for the availability of magnesium protoporphyrin for plastid-to-nucleus signalling.

Item Type: Article
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Mark Shepherd
Date Deposited: 01 Sep 2011 16:06
Last Modified: 24 Apr 2014 08:06
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