1l6w

From Proteopedia

Revision as of 18:12, 20 November 2007

Fructose-6-phosphate aldolase

Overview

Fructose-6-phosphate aldolase from Escherichia coli is a member of a small, enzyme subfamily (MipB/TalC family) that belongs to the class I aldolases., The three-dimensional structure of this enzyme has been determined at 1.93, A resolution by single isomorphous replacement and tenfold, non-crystallographic symmetry averaging and refined to an R-factor of, 19.9% (R(free) 21.3%). The subunit folds into an alpha/beta barrel, with, the catalytic lysine residue on barrel strand beta 4. It is very similar, in overall structure to that of bacterial and mammalian transaldolases, although more compact due to extensive deletions of additional secondary, structural elements. The enzyme forms a decamer of identical subunits with, point group symmetry 52. Five subunits are arranged as a pentamer, and two, ring-like pentamers pack like a doughnut to form the decamer. A major, interaction within the pentamer is through the C-terminal helix from one, monomer, which runs across the active site of the neighbouring subunit. In, classical transaldolases, this helix folds back and covers the active site, of the same subunit and is involved in dimer formation. The inter-subunit, helix swapping appears to be a major determinant for the formation of, pentamers rather than dimers while at the same time preserving importing, interactions of this helix with the active site of the enzyme. The active, site lysine residue is covalently modified, by forming a carbinolamine, with glyceraldehyde from the crystallisation mixture. The catalytic, machinery is very similar to that of transaldolase, which together with, the overall structural similarity suggests that enzymes of the MipB/TALC, subfamily are evolutionary related to the transaldolase family.

About this Structure

1L6W is a Single protein structure of sequence from Escherichia coli with GOL as ligand. Full crystallographic information is available from OCA.

Reference

Crystal structure of decameric fructose-6-phosphate aldolase from Escherichia coli reveals inter-subunit helix swapping as a structural basis for assembly differences in the transaldolase family., Thorell S, Schurmann M, Sprenger GA, Schneider G, J Mol Biol. 2002 May 24;319(1):161-71. PMID:12051943

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