2x31

Publication Abstract from PubMed

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.

ATP-induced conformational dynamics in the AAA+ motor unit of magnesium chelatase.,Lundqvist J, Elmlund H, Wulff RP, Berglund L, Elmlund D, Emanuelsson C, Hebert H, Willows RD, Hansson M, Lindahl M, Al-Karadaghi S Structure. 2010 Mar 10;18(3):354-65. PMID:20223218^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.