1m5h
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(New page: 200px<br /><applet load="1m5h" size="450" color="white" frame="true" align="right" spinBox="true" caption="1m5h, resolution 2.00Å" /> '''Formylmethanofuran:t...)
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Revision as of 19:02, 20 November 2007
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Formylmethanofuran:tetrahydromethanopterin formyltransferase from Archaeoglobus fulgidus
Overview
Formyltransferase catalyzes the reversible formation of formylmethanofuran, from N(5)-formyltetrahydromethanopterin and methanofuran, a reaction, involved in the C1 metabolism of methanogenic and sulfate-reducing, archaea. The crystal structure of the homotetrameric enzyme from, Methanopyrus kandleri (growth temperature optimum 98 degrees C) has, recently been solved at 1.65 A resolution. We report here the crystal, structures of the formyltransferase from Methanosarcina barkeri (growth, temperature optimum 37 degrees C) and from Archaeoglobus fulgidus (growth, temperature optimum 83 degrees C) at 1.9 A and 2.0 A resolution, respectively. Comparison of the structures of the three enzymes revealed, very similar folds. The most striking difference found was the negative, surface charge, which was -32 for the M. kandleri enzyme, only -8 for the, M. barkeri enzyme, and -11 for the A. fulgidus enzyme. The hydrophobic, surface fraction was 50% for the M. kandleri enzyme, 56% for the M., barkeri enzyme, and 57% for the A. fulgidus enzyme. These differences most, likely reflect the adaptation of the enzyme to different cytoplasmic, concentrations of potassium cyclic 2,3-diphosphoglycerate, which are very, high in M. kandleri (>1 M) and relatively low in M. barkeri and A., fulgidus. Formyltransferase is in a monomer/dimer/tetramer equilibrium, that is dependent on the salt concentration. Only the dimers and tetramers, are active, and only the tetramers are thermostable. The enzyme from M., kandleri is a tetramer, which is active and thermostable only at high, concentrations of potassium phosphate (>1 M) or potassium cyclic, 2,3-diphosphoglycerate. Conversely, the enzyme from M. barkeri and A., fulgidus already showed these properties, activity and stability, at much, lower concentrations of these strong salting-out salts.
About this Structure
1M5H is a Single protein structure of sequence from Archaeoglobus fulgidus with K as ligand. Active as Formylmethanofuran--tetrahydromethanopterin N-formyltransferase, with EC number 2.3.1.101 Full crystallographic information is available from OCA.
Reference
Crystal structures and enzymatic properties of three formyltransferases from archaea: environmental adaptation and evolutionary relationship., Mamat B, Roth A, Grimm C, Ermler U, Tziatzios C, Schubert D, Thauer RK, Shima S, Protein Sci. 2002 Sep;11(9):2168-78. PMID:12192072
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