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1gn6

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Revision as of 17:47, 30 March 2008 by OCA (Talk | contribs)
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PDB ID 1gn6

Drag the structure with the mouse to rotate
, resolution 2.9Å
Sites:
Ligands:
Activity: Superoxide dismutase, with EC number 1.15.1.1
Resources: FirstGlance, OCA, PDBsum, RCSB
Coordinates: save as pdb, mmCIF, xml



G152A MUTANT OF MYCOBACTERIUM TUBERCULOSIS IRON-SUPEROXIDE DISMUTASE.


Overview

We have refined the X-ray structure of a site-directed G152A mutant of the iron-dependent superoxide dismutase from Mycobacterium tuberculosis at 2.9 angstroms resolution. The mutation which replaces a glycine residue in a surface loop with alanine was designed to alter the conformation of this loop region which has previously been shown to play a crucial structural role in quaternary interactions within the SOD tetramer. Gly-152 was targeted as it has dihedral angles (phi = 83.1 degrees, psi = -0.3 degrees) close to the left-handed alpha-helical conformation which is rarely adopted by other amino acids except asparagine. Gly-152 was replaced by alanine as it has similar size and polarity, yet has a very low tendency to adopt similar conformations. X-ray data collection on crystals of this mutant at 2.9 angstroms resolution and subsequent least-squares refinement to an R-value of 0.169 clearly establish that the loop conformation is unaffected. Fluorescence studies of guanidine hydrochloride denaturation establish that the mutant is 4 kcal/mol less stable than the wild-type enzyme. Our results indicate that strict conformational constraints imposed upon a region of polypeptide, due for example to interactions with a neighbouring subunit, may force an alanine residue to adopt this sterically hindered conformation with a consequent reduction in stability of the folded conformation.

About this Structure

1GN6 is a Single protein structure of sequence from Mycobacterium tuberculosis. Full crystallographic information is available from OCA.

Reference

X-ray structure analysis of an engineered Fe-superoxide dismutase Gly-Ala mutant with significantly reduced stability to denaturant., Cooper JB, Saward S, Erskine PT, Badasso MO, Wood SP, Zhang Y, Young D, FEBS Lett. 1996 Jun 3;387(2-3):105-8. PMID:8674528

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