1snm
ACTIVE SITE MUTANT GLU-43 (RIGHT ARROW) ASP IN STAPHYLOCOCCAL NUCLEASE DISPLAYS NONLOCAL STRUCTURAL CHANGES
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OverviewOverview
The crystal structure of the Glu-43----Asp mutant of staphylococcal, nuclease complexed with Ca2+ and the inhibitor thymidine, 3',5'-bisphosphate (pdTp) has been determined and refined by restrained, least-squares methods to a conventional crystallographic R value of 0.174, at a resolution of 1.74 A. Throughout most of the structure, the, conformation of the backbone atoms of the mutant is similar to that of the, wild-type protein; however, the seemingly conservative mutation Glu----Asp, has significantly perturbed the structure of a loop adjacent to the active, site, as well as giving rise to looser binding of the essential calcium, ion and to a less extensive network of bound water molecules in the active, site. Crystal contacts that extend into the active site have also been, altered by this amino acid substitution. The changes caused by this, mutation are considerably more drastic than would have been predicted and, should serve as caveats to those who would draw conclusions about, structure-function relationships on the basis of site-directed mutagenesis, experiments in the absence of structural data.
About this StructureAbout this Structure
1SNM is a Single protein structure of sequence from Staphylococcus aureus with CA and THP as ligands. Active as Micrococcal nuclease, with EC number 3.1.31.1 Full crystallographic information is available from OCA.
ReferenceReference
Active site mutant Glu-43----Asp in staphylococcal nuclease displays nonlocal structural changes., Loll PJ, Lattman EE, Biochemistry. 1990 Jul 24;29(29):6866-73. PMID:2397218
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