title: Insights into open/closed conformations of the catalytically active human guanylate kinase as investigated by small-angle X-ray scattering.
abstract: Bio-catalysis is the outcome of a subtle interplay between internal motions in enzymes and chemical kinetics. Small-angle X-ray scattering (SAXS) investigation of an enzyme's internal motions during catalysis offers an integral view of the protein's structural plasticity, dynamics, and function, which is useful for understanding allosteric effects and developing novel medicines. Guanylate kinase (GMPK) is an essential enzyme involved in the guanine nucleotide metabolism of unicellular and multicellular organisms. It is also required for the intracellular activation of numerous antiviral and anticancer purine nucleoside analog prodrugs. Catalytically active recombinant human GMPK (hGMPK) was purified for the first time and changes in the size and shape of open/closed hGMPK were tracked by SAXS. The binding of substrates (GMP + AMPPNP or Ap5G or GMP + ADP) resulted in the compaction of size and shape of hGMPK. The structural changes between open and completely closed hGMPK conformation were confirmed by observing differences in the hGMPK secondary structures with circular dichroism spectroscopy.
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
authors.forename: Rohit
authors.initials: R
authors.lastname: Jain
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
authors.forename: Nazimuddin
authors.initials: N
authors.lastname: Khan
authors.affiliation: Paul Scherrer Institute, 5232, Villingen, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Menzel
authors.affiliation: Paul Scherrer Institute, 5232, Villingen, Switzerland.
authors.forename: Ivan
authors.initials: I
authors.lastname: Rajkovic
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany. mkonrad@mpibpc.mpg.de.
authors.forename: Manfred
authors.initials: M
authors.lastname: Konrad
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany. stecher@mpibpc.mpg.de.|Institute for X-ray Physics at University of Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany. stecher@mpibpc.mpg.de.|FS-SCS at DESY, Notkestraße 85, 22607, Hamburg, Germany. stecher@mpibpc.mpg.de.
authors.forename: Simone
authors.initials: S
authors.lastname: Techert
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D006162:Guanylate Cyclase / Q000737:chemistry*; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D006162:Guanylate Cyclase
keywords: Enzyme; Guanylate kinase (GMPK); Nucleotide kinase; Protein conformations; Small-angle X-ray scattering (SAXS)