Download MendeleyATP-Induced Conformational Dynamics in the Aaa+ Motor Unit of Magnesium Chelatase.
Lundqvist, J., Elmlund, H., Wulff, R.P., Berglund, L., Elmlund, D., Emanuelsson, C., Hebert, H., Willows, R.D., Hansson, M., Lindahl, M., Al-Karadaghi, S.(2010) Structure 18: 354
- PubMed: 20223218
- DOI: https://doi.org/10.1016/j.str.2010.01.001
- Primary Citation of Related Structures:
2X31 - PubMed Abstract:
Mg-chelatase catalyzes the first committed step of the chlorophyll biosynthetic pathway, the ATP-dependent insertion of Mg(2+) into protoporphyrin IX (PPIX). Here we report the reconstruction using single-particle cryo-electron microscopy of the complex between subunits BchD and BchI of Rhodobacter capsulatus Mg-chelatase in the presence of ADP, the nonhydrolyzable ATP analog AMPPNP, and ATP at 7.5 A, 14 A, and 13 A resolution, respectively. We show that the two AAA+ modules of the subunits form a unique complex of 3 dimers related by a three-fold axis. The reconstructions demonstrate substantial differences between the conformations of the complex in the presence of ATP and ADP, and suggest that the C-terminal integrin-I domains of the BchD subunits play a central role in transmitting conformational changes of BchI to BchD. Based on these data a model for the function of magnesium chelatase is proposed.
Organizational Affiliation:
Department of Molecular Biophysics, Centre for Molecular Protein Science, Lund University, Lund, Sweden. joakim@crc.dk
