1zw8

From Proteopedia

---

Revision as of 05:34, 21 November 2007

proteopedia linkproteopedia link

spinqualitylabelsall models 1zw8 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Solution structure of a ZAP1 zinc-responsive domain provides insights into metalloregulatory transcriptional repression in Saccharomyces cerevisiae

Overview

The Zap1 transcription factor controls expression of genes that regulate, zinc homeostasis in Saccharomyces cerevisiae. The solution structure of, two zinc fingers (zf1-2(CA3)) derived from a zinc-responsive domain of, Zap1 (zf1-2) has been determined. Under zinc-limiting conditions, zinc, finger 2 (zf2) from this domain has been shown to be a constitutive, transcriptional activator. Moreover, repression of zf2 function in, zinc-replete cells required zinc coordination to both canonical finger 1, (zf1) and zf2 metal sites, suggesting zf1-zf2 cooperativity underlies Zap1, metalloregulation. A structural basis for this cooperativity is identified, here. Favorable inter-helical contacts in zf1-2(CA3) extend the individual, finger hydrophobic cores through the zf1-zf2 interface. Tryptophan, residues at position 5 in each finger provide numerous non-helical, inter-finger contacts reminiscent of those observed in GLI1 zinc fingers 1, and 2. The molecular mechanism for zf1-dependent repression of zf2, transcriptional activation is explored further using NMR and CD titration, studies. While zf1 independently forms a betabetaalpha solution structure, the majority of zf2 ensemble solution states do not adopt the canonical, betabetaalpha zinc finger fold without zf1-zf2 interactions. Cooperative, effects on Zn(II) affinities stemming from these finger-finger, interactions are observed also in calorimetric studies, in which the, 160(+/-20)nM (zf1) and 250(+/-40)nM (zf2) K(d) values for each individual, finger increased substantially in the context of the zf1-2 protein, (apparent K(dzf1-2WT)=4.6(+/-1.2)nM). On the basis of the above, observations, we propose a mechanism for Zap1 transcriptional regulation, in which zf1-zf2 interactions stabilize the betabetaalpha folded, "repressed state" of the zf2 activation domain in the presence of cellular, Zn(II) excess. Moreover, in contrast to earlier reports of <<1 labile zinc, ion/Escherichia coli cell, the zf1-zf2 zinc affinities determined, calorimetrically are consistent with Zn(II) levels >>1 labile zinc, ion/eukaryotic cell.

About this Structure

1ZW8 is a Single protein structure of sequence from Saccharomyces cerevisiae with ZN as ligand. Full crystallographic information is available from OCA.

Reference

Solution structure of a Zap1 zinc-responsive domain provides insights into metalloregulatory transcriptional repression in Saccharomyces cerevisiae., Wang Z, Feng LS, Matskevich V, Venkataraman K, Parasuram P, Laity JH, J Mol Biol. 2006 Apr 7;357(4):1167-83. Epub 2006 Jan 24. PMID:16483601

Page seeded by OCA on Wed Nov 21 07:42:01 2007