2PS3

Structure and metal binding properties of ZnuA, a periplasmic zinc transporter from Escherichia coli

Summary for 2PS3

• Entry DOI: 10.2210/pdb2ps3/pdb
• Related: 2OGW 2OSV 2PRS 2PS0 2PS9
• Descriptor: High-affinity zinc uptake system protein znuA (2 entities in total)
• Functional Keywords: the protein consists of two domains with a typical (beta/alfa)4 fold, metal transport
• Biological source: Escherichia coli
• Cellular location: Periplasm: P39172
• Total number of polymer chains: 2
• Total formula weight: 62354.44

Authors

Yatsunyk, L.A.,Kim, L.R.,Vorontsov, I.I.,Rosenzweig, A.C. (deposition date: 2007-05-04, release date: 2007-06-05, Last modification date: 2024-11-20)

Primary citation

Yatsunyk, L.A.,Easton, J.A.,Kim, L.R.,Sugarbaker, S.A.,Bennett, B.,Breece, R.M.,Vorontsov, I.I.,Tierney, D.L.,Crowder, M.W.,Rosenzweig, A.C.
Structure and metal binding properties of ZnuA, a periplasmic zinc transporter from Escherichia coli.
J.Biol.Inorg.Chem., 13:271-288, 2008

PubMed Abstract: ZnuA is the periplasmic Zn(2+)-binding protein associated with the high-affinity ATP-binding cassette ZnuABC transporter from Escherichia coli. Although several structures of ZnuA and its homologs have been determined, details regarding metal ion stoichiometry, affinity, and specificity as well as the mechanism of metal uptake and transfer remain unclear. The crystal structures of E. coli ZnuA (Eco-ZnuA) in the apo, Zn(2+)-bound, and Co(2+)-bound forms have been determined. ZnZnuA binds at least two metal ions. The first, observed previously in other structures, is coordinated tetrahedrally by Glu59, His60, His143, and His207. Replacement of Zn(2+) with Co(2+) results in almost identical coordination geometry at this site. The second metal binding site involves His224 and several yet to be identified residues from the His-rich loop that is unique to Zn(2+) periplasmic metal binding receptors. Electron paramagnetic resonance and X-ray absorption spectroscopic data on CoZnuA provide additional insight into possible residues involved in this second site. The second site is also detected by metal analysis and circular dichroism (CD) titrations. Eco-ZnuA binds Zn(2+) (estimated K (d) < 20 nM), Co(2+), Ni(2+), Cu(2+), Cu(+), and Cd(2+), but not Mn(2+). Finally, conformational changes upon metal binding observed in the crystal structures together with fluorescence and CD data indicate that only Zn(2+) substantially stabilizes ZnuA and might facilitate recognition of ZnuB and subsequent metal transfer.

PubMed: 18027003
DOI: 10.1007/s00775-007-0320-0

Experimental method

X-RAY DIFFRACTION (2.47 Å)