Structure/function studies on a S-adenosyl-L-methionine-dependent uroporphyrinogen III C methyltransferase (SUMT), a key regulatory enzyme of tetrapyrrole biosynthesis

Vevodova, J. and Graham, R.M. and Raux, E. and Schubert, H.L. and Roper, D.I. and Brindley, A.A. and Ian Scott, A. and Roessner, C.A. and Stamford, N.P. and Elizabeth Stroupe, M. and Getzoff, E.D. and Warren, M.J. and Wilson, K.S. (2004) Structure/function studies on a S-adenosyl-L-methionine-dependent uroporphyrinogen III C methyltransferase (SUMT), a key regulatory enzyme of tetrapyrrole biosynthesis. Journal of Molecular Biology, 344 (2). pp. 419-33. ISSN 0022-2836 . (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1016/j.jmb.2004.09.020

Abstract

The crystallographic structure of the Pseudomonas denitrificans S-adenosyl-L-methionine-dependent uroporphyrinogen III methyltransferase (SUMT), which is encoded by the cobA gene, has been solved by molecular replacement to 2.7A resolution. SUMT is a branchpoint enzyme that plays a key role in the biosynthesis of modified tetrapyrroles by controlling flux to compounds such as vitamin B(12) and sirohaem, and catalysing the transformation of uroporphyrinogen III into precorrin-2. The overall topology of the enzyme is similar to that of the SUMT module of sirohaem synthase (CysG) and the cobalt-precorrin-4 methyltransferase CbiF and, as with the latter structures, SUMT has the product S-adenosyl-L-homocysteine bound in the crystal. The roles of a number of residues within the SUMT structure are discussed with respect to their conservation either across the broader family of cobalamin biosynthetic methyltransferases or within the sub-group of SUMT members. The D47N, L49A, F106A, T130A, Y183A and M184A variants of SUMT were generated by mutagenesis of the cobA gene, and tested for SAM binding and enzymatic activity. Of these variants, only D47N and L49A bound the co-substrate S-adenosyl-L-methionine. Consequently, all the mutants were severely restricted in their capacity to synthesise precorrin-2, although both the D47N and L49A variants produced significant quantities of precorrin-1, the monomethylated derivative of uroporphyrinogen III. The activity of these variants is interpreted with respect to the structure of the enzyme.

Item Type: Article
Additional information: 0022-2836 (Print) Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.
Uncontrolled keywords: Amino Acid Sequence Amino Acid Substitution Bacterial Proteins/*chemistry/genetics/*metabolism Binding Sites Catalysis Crystallography, X-Ray Dimerization *Gene Expression Regulation, Enzymologic Genes, Bacterial Hydrogen Bonding Ligands Methyltransferases/*chemistry/genetics/*metabolism Models, Molecular Molecular Sequence Data Molecular Structure Mutagenesis, Site-Directed Protein Conformation Protein Folding Protein Structure, Secondary Protein Structure, Tertiary Protein Subunits/chemistry Pseudomonas Infections/enzymology Sequence Homology, Amino Acid Structure-Activity Relationship Substrate Specificity Tetrapyrroles/*biosynthesis Variation (Genetics)
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Martin Warren
Date Deposited: 07 Oct 2009 08:14
Last Modified: 14 Jan 2010 14:42
Resource URI: http://kar.kent.ac.uk/id/eprint/11045 (The current URI for this page, for reference purposes)
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