分类: 生物学 >> 生物物理学 提交时间: 2016-05-11
摘要: Adaptations to hypoxia play an important role in Mycobacterium tuberculosis pathogenesis. Rv0324, which contains an HTH DNA-binding domain and a rhodanese domain, is one of the key transcription regulators in response to hypoxia. M. tuberculosis Rv1674c is a homologue of Rv0324. To understand the interdomain interaction and regulation of the HTH domain and the rhodanese domain, recombinant Rv1674c protein was purified and crystallized by the vapour-diffusion method. The crystals diffracted to 2.25 angstrom resolution. Preliminary diffraction analysis suggests that the crystals belonged to space group P3(1)21 or P3(2)21, with unit-cell parameters a = b = 67.8, c = 174.5 angstrom, alpha = beta = 90, gamma = 120 degrees. The Matthews coefficient was calculated to be 2.44 angstrom(3) Da(-1), assuming that the crystallographic asymmetric unit contains two protein molecules.
分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-12
摘要: The homeostasis of magnesium (Mg2+), an abundant divalent cation indispensable for many biological processes including mitochondrial functions, is underexplored. Previously, two mitochondrial Mg2+ importers, Mrs2 and Lpe10, were characterized for mitochondrial Mg2+ uptake. We now show that mitochondrial Mg2+ homeostasis is accurately controlled through the combined effects of previously known importers and a novel exporter, Mme1 (mitochondrial magnesium exporter 1). Mme1 belongs to the mitochondrial carrier family and was isolated for its mutation that is able to suppress the mrs2 Delta respiration defect. Deletion of MME1 significantly increased steady-state mitochondrial Mg2+ concentration, while overexpression decreased it. Measurements of Mg2+ exit from proteoliposomes reconstituted with purified Mme1 provided definite evidence for Mme1 as an Mg2+ exporter. Our studies identified, for the first time, a mitochondrial Mg2+ exporter that works together with mitochondrial importers to ensure the precise control of mitochondrial Mg2+ homeostasis. (C) 2015 Elsevier B.V. All rights reserved.