This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1g15
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1g15" size="450" color="white" frame="true" align="right" spinBox="true" caption="1g15, resolution 1.9Å" /> '''CO-CRYSTAL OF E. COLI...)
Next diff →
Revision as of 13:29, 20 November 2007
|
CO-CRYSTAL OF E. COLI RNASE HI WITH TWO MN2+ IONS BOUND IN THE THE ACTIVE SITE
Overview
Ribonuclease H (RNase H) selectively degrades the RNA strand of RNA.DNA, hybrids in a divalent cation-dependent manner. Previous structural studies, revealed a single Mg(2+) ion-binding site in Escherichia coli RNase HI. In, the crystal structure of the related RNase H domain of human, immunodeficiency virus reverse transcriptase, however, two Mn(2+) ions, were observed suggesting a different mode of metal binding. E. coli RNase, HI shows catalytic activity in the presence of Mg(2+) or Mn(2+) ions, but, these two metals show strikingly different optimal concentrations. Mg(2+), ions are required in millimolar concentrations, but Mn(2+) ions are only, required in micromolar quantities. Based upon the metal dependence of E., coli RNase HI activity, we proposed an activation/attenuation model in, which one metal is required for catalysis, and binding of a second metal, is inhibitory. We have now solved the co-crystal structure of E. coli, RNase HI with Mn(2+) ions at 1.9-A resolution. Two octahedrally, coordinated Mn(2+) ions are seen to bind to the enzyme-active site., Residues Asp-10, Glu-48, and Asp-70 make direct (inner sphere), coordination contacts to the first (activating) metal, whereas residues, Asp-10 and Asp-134 make direct contacts to the second (attenuating) metal., This structure is consistent with biochemical evidence suggesting that two, metal ions may bind RNase H but liganding a second ion inhibits RNase H, activity.
About this Structure
1G15 is a Single protein structure of sequence from Escherichia coli with MN as ligand. Active as Ribonuclease H, with EC number 3.1.26.4 Full crystallographic information is available from OCA.
Reference
Co-crystal of Escherichia coli RNase HI with Mn2+ ions reveals two divalent metals bound in the active site., Goedken ER, Marqusee S, J Biol Chem. 2001 Mar 9;276(10):7266-71. Epub 2000 Nov 16. PMID:11083878
Page seeded by OCA on Tue Nov 20 15:36:44 2007
