title: Binding of calcium in the EF-hand of Escherichia coli lytic transglycosylase Slt35 is important for stability.
abstract: The Escherichia coli lytic transglycosylase Slt35 contains a single metal ion-binding site that resembles EF-hand calcium-binding sites. The Slt35 EF-hand is only the second observation of such a domain in a prokaryotic protein. Two crystal structures at 2.1 A resolution show that both Ca2+ ions and Na+ ions can bind to the EF-hand domain, but in subtly different configurations. Heat-induced unfolding studies demonstrate that Ca2+ ions are preferentially bound, and that only Ca2+ ions significantly increase the melting temperature of Slt35. This shows that the EF-hand calcium-binding domain is important for the stability of Slt35.
authors.affiliation: BIOSON Research Institute and Laboratory of Biophysical Chemistry, University of Groningen, The Netherlands.
authors.forename: E J
authors.initials: EJ
authors.lastname: van Asselt
authors.forename: B W
authors.initials: BW
authors.lastname: Dijkstra
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D020832:EF Hand Motifs; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology*; D016695:Glycosyltransferases / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation / Q000187:drug effects; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence; D013696:Temperature
chemical_list: D016695:Glycosyltransferases; C021815:murein transglycosylase; D002118:Calcium