Related Experiment Video
Updated: Jun 30, 2026

Combining X-Ray Crystallography with Small Angle X-Ray Scattering to Model Unstructured Regions of Nsa1 from S. Cerevisiae
Published on: January 10, 2018
The structure of urease activation complexes examined by flexibility analysis, mutagenesis, and small-angle X-ray
Soledad Quiroz-Valenzuela1, Sai Chetan K Sukuru, Robert P Hausinger
1Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
Abstract:
Conformational changes of Klebsiella aerogenes urease apoprotein (UreABC)(3) induced upon binding of the UreD and UreF accessory proteins were examined by a combination of flexibility analysis, mutagenesis, and small-angle X-ray scattering (SAXS). ProFlex analysis of urease provided evidence that the major domain of UreB can move in a hinge-like motion to account for prior chemical cross-linking results. Rigidification of the UreB hinge region, accomplished through a G11P mutation, reduced the extent of urease activation, in part by decreasing the nickel content of the mutant enzyme, and by sequestering a portion of the urease apoprotein in a novel activation complex that includes all of the accessory proteins. SAXS analyses of urease, (UreABC-UreD)(3), and (UreABC-UreDF)(3) confirm that UreD and UreF bind near UreB at the periphery of the (UreAC)(3) structure. This study supports an activation model in which a domain-shifted UreB conformation in (UreABC-UreDF)(3) allows CO(2) and nickel ions to gain access to the nascent active site.
Related Concept Videos
Ligand Binding and Linkage
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Enzymes
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Induced-fit Model
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Introduction to Mechanisms of Enzyme Catalysis

