| 1. |
- Fodje, Michel, et al.
(author)
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Interplay Between an AAA Module and an Integrin I Domain May Regulate the Function of Magnesium Chelatase
- 2001
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In: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 311:1, s. 111-122
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Journal article (peer-reviewed)abstract
- In chlorophyll biosynthesis, insertion of Mg2+ into protoporphyrin IX is catalysed in an ATP-dependent reaction by a three-subunit (BchI, BchD and BchH) enzyme magnesium chelatase. In this work we present the three-dimensional structure of the ATP-binding subunit BchI. The structure has been solved by the multiple wavelength anomalous dispersion method and refined at 2.1 A resolution to the crystallographic R-factor of 22.2 % (Rfree = 24.5 %). It belongs to the chaperone-like ''ATPase associated with a variety of cellular activities'' (AAA) family of ATPases, with a novel arrangement of domains: the C-terminal helical domain is located behind the nucleotide-binding site, while in other known AAA module structures it is located on the top. Examination by electron microscopy of BchI solutions in the presence of ATP demonstrated that BchI, like other AAA proteins, forms oligomeric ring structures. Analysis of the amino acid sequence of subunit BchD revealed an AAA module at the N-terminal portion of the sequence and an integrin I domain at the C terminus. An acidic, proline-rich region linking these two domains is suggested to contribute to the association of BchI and BchD by binding to a positively charged cleft at the surface of the nucleotide-binding domain of BchI. Analysis of the amino acid sequences of BchI and BchH revealed integrin I domain-binding sequence motifs. These are proposed to bind the integrin I domain of BchD during the functional cycle of magnesium chelatase, linking porphyrin metallation by BchH to ATP hydrolysis by BchI. An integrin I domain and an acidic and proline-rich region have been identified in subunit CobT of cobalt chelatase, clearly demonstrating its homology to BchD. These findings, for the first time, provide an insight into the subunit organisation of magnesium chelatase and the homologous colbalt chelatase.
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| 2. |
- Al-Karadaghi, Salam, et al.
(author)
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Chelatases: distort to select?
- 2006
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In: Trends in Biochemical Sciences. - : Elsevier BV. - 0167-7640 .- 0968-0004. ; 31:3, s. 135-142
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Journal article (other academic/artistic)abstract
- Chelatases catalyze the insertion of a specific metal ion into porphyrins, a key step in the synthesis of metalated tetrapyrroles that are essential for many cellular processes. Despite apparent common structural features among chelatases, no general reaction mechanism accounting for metal ion specificity has been established. We propose that chelatase-induced distortion of the porphyrin substrate not only enhances the reaction rate by decreasing the activation energy of the reaction but also modulates which divalent metal ion is incorporated into the porphyrin ring. We evaluate the recently recognized interaction between ferrochelatase and frataxin as a way to regulate iron delivery to ferrochelatase, and thus iron and heme metabolism. We postulate that the ferrochelatase-frataxin interaction controls the type of metal ion that is delivered to ferrochelatase.
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| 3. |
- Hansson, Mats, et al.
(author)
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Magnesium chelatase: The molecular motor of chlorophyll biosynthesis.
- 2014
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In: Handbook of Porphyrin Science with Applications to Chemistry, Physics, Materials Science, Engineering, Biology and Medicine. Vol 28. Chlorophyll, Photosynthesis and Bio-Inspired Energy. - 1793-9518. - 9789814407793 ; 28, s. 41-84
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Book chapter (peer-reviewed)
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