title: Crystallization and preliminary X-ray analysis of the ergothioneine-biosynthetic methyltransferase EgtD.
abstract: Ergothioneine is an amino-acid betaine derivative of histidine that was discovered more than one century ago. Despite significant research pointing to a function in oxidative stress defence, the exact mechanisms of action of ergothioneine remain elusive. Although both humans and bacterial pathogens such as Mycobacterium tuberculosis seem to depend on ergothioneine, humans are devoid of the corresponding biosynthetic enzymes. Therefore, its biosynthesis may emerge as potential drug target in the development of novel therapeutics against tuberculosis. The recent identification of ergothioneine-biosynthetic genes in M. smegmatis enables a more systematic study of its biology. The pathway is initiated by EgtD, a SAM-dependent methyltransferase that catalyzes a trimethylation reaction of histidine to give N(α),N(α),N(α)-trimethylhistidine. Here, the recombinant production, purification and crystallization of EgtD are reported. Crystals of native EgtD diffracted to 2.35 Å resolution at a synchrotron beamline, whereas crystals of seleno-L-methionine-labelled protein diffracted to 1.75 Å resolution and produced a significant anomalous signal to 2.77 Å resolution at the K edge. All of the crystals belonged to space group P212121, with two EgtD monomers in the asymmetric unit.
authors.affiliation: Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
authors.forename: Allegra
authors.initials: A
authors.lastname: Vit
authors.affiliation: Department of Chemistry, University of Basel, St Johanns-Ring 19, 4056 Basel, Switzerland.
authors.forename: Laëtitia
authors.initials: L
authors.lastname: Misson
authors.affiliation: Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
authors.forename: Wulf
authors.initials: W
authors.lastname: Blankenfeldt
authors.affiliation: Department of Chemistry, University of Basel, St Johanns-Ring 19, 4056 Basel, Switzerland.
authors.forename: Florian Peter
authors.initials: FP
authors.lastname: Seebeck
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D004880:Ergothioneine / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D008780:Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000201:enzymology* / Q000235:genetics
chemical_list: D004880:Ergothioneine; D008780:Methyltransferases
keywords: biosynthesis; ergothioneine; mycobacteria; selenium SAD