title: Flexibility of truncated and full-length glucansucrase GTF180 enzymes from Lactobacillus reuteri 180.
abstract: Glucansucrase enzymes synthesize high-molecular-mass extracellular α-glucan polysaccharides from sucrose. Previously, the crystal structure of truncated glucansucrase glucosyltransferase (GTF)180-ΔN from Lactobacillus reuteri 180 (lacking the N-terminal domain) revealed an elongated overall structure with two remote domains (IV and V) extending away from the core. By contrast, a new crystal form of the α-1,6/α-1,3 specific glucansucrase GTF180-ΔN shows an approximate 120(o) rotation of domain V about a hinge located between domains IV and V, giving a much more compact structure than before. Positional variability of domain V in solution is confirmed by small angle X-ray scattering experiments and rigid-body ensemble calculations. In addition, small angle X-ray scattering measurements of full-length GTF180 also provide the first structural data for a full-length glucansucrase, showing that the enzyme has an almost symmetric boomerang-like molecular shape, with a bend likely located between domains IV and V. The ~ 700-residue N-terminal domain, which is not present in the crystal structures, extends away from domain V and the catalytic core of the enzyme. We conclude that, as a result of the hinge region, in solution, GTF180-ΔN (and likely also the full-length GTF180) shows conformational flexibility; this may be a general feature of GH70 glucansucrases.
  
  
  METHODS
  • Structural data for GTF180-ΔN II have been deposited in the Protein Data Bank under accession code 4AYG.
authors.affiliation: Laboratory of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, The Netherlands.
authors.forename: Tjaard
authors.initials: T
authors.lastname: Pijning
authors.forename: Andreja
authors.initials: A
authors.lastname: Vujičić-Žagar
authors.forename: Slavko
authors.initials: S
authors.lastname: Kralj
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: Bauke W
authors.initials: BW
authors.lastname: Dijkstra
mesh_terms: D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D016695:Glycosyltransferases / Q000737:chemistry / Q000378:metabolism*; D052200:Limosilactobacillus reuteri / Q000201:enzymology*; D008958:Models, Molecular; D011487:Protein Conformation; D053838:Scattering, Small Angle
chemical_list: D016695:Glycosyltransferases; C033837:alternansucrase
keywords: GTF180; SAXS; crystal structure; glucansucrase; rigid-body ensemble calculations