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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
2-3
|
| pubmed:dateCreated |
1996-8-15
|
| pubmed:abstractText |
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:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Jun
|
| pubmed:issn |
0014-5793
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
3
|
| pubmed:volume |
387
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
105-8
|
| pubmed:dateRevised |
2000-12-18
|
| pubmed:meshHeading |
pubmed-meshheading:8674528-Alanine,
pubmed-meshheading:8674528-Base Sequence,
pubmed-meshheading:8674528-Crystallography, X-Ray,
pubmed-meshheading:8674528-DNA, Bacterial,
pubmed-meshheading:8674528-Electrochemistry,
pubmed-meshheading:8674528-Glycine,
pubmed-meshheading:8674528-Molecular Sequence Data,
pubmed-meshheading:8674528-Mutagenesis, Site-Directed,
pubmed-meshheading:8674528-Mycobacterium tuberculosis,
pubmed-meshheading:8674528-Protein Conformation,
pubmed-meshheading:8674528-Protein Denaturation,
pubmed-meshheading:8674528-Spectrometry, Fluorescence,
pubmed-meshheading:8674528-Superoxide Dismutase
|
| pubmed:year |
1996
|
| pubmed:articleTitle |
X-ray structure analysis of an engineered Fe-superoxide dismutase Gly-Ala mutant with significantly reduced stability to denaturant.
|
| pubmed:affiliation |
Department of Crystallography, Birkbeck College, University of London, UK.
|
| pubmed:publicationType |
Journal Article
|