1GN6

G152A mutant of Mycobacterium tuberculosis iron-superoxide dismutase.

Summary for 1GN6

• Entry DOI: 10.2210/pdb1gn6/pdb
• Related: 1GN2 1GN3 1GN4 1IDS
• Descriptor: SUPEROXIDE DISMUTASE, FE (III) ION (3 entities in total)
• Functional Keywords: oxidoreductase
• Biological source: MYCOBACTERIUM TUBERCULOSIS
• Total number of polymer chains: 4
• Total formula weight: 92522.94

Authors

Bunting, K.A.,Cooper, J.B.,Saward, S.,Erskine, P.T.,Badasso, M.O.,Wood, S.P.,Zhang, Y.,Young, D.B. (deposition date: 2001-10-03, release date: 2001-10-05, Last modification date: 2024-05-08)

Primary citation

Cooper, J.B.,Saward, S.,Erskine, P.T.,Badasso, M.O.,Wood, S.P.,Zhang, Y.,Young, D.B.
X-Ray Structure Analysis of an Engineered Fe-Superoxide Dismutase Gly-Ala Mutant with Significantly Reduced Stability to Denaturant
FEBS Lett., 387:105-, 1996

PubMed Abstract: 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.

PubMed: 8674528
DOI: 10.1016/0014-5793(96)00490-5

Experimental method

X-RAY DIFFRACTION (2.9 Å)