title: A dual role for an aspartic acid in glycosylasparaginase autoproteolysis.
abstract: Glycosylasparaginase uses an autoproteolytic processing mechanism, through an N-O acyl shift, to generate a mature/active enzyme from a single-chain precursor. Structures of glycosylasparaginase precursors in complex with a glycine inhibitor have revealed the backbone in the immediate vicinity of the scissile peptide bond to be in a distorted trans conformation, which is believed to be the driving force for the N-O acyl shift to break the peptide bond. Here we report the effects of point mutation D151N. In addition to the loss of the base essential in autoproteolysis, this mutation also eradicates the backbone distortion near the scissile peptide bond. Binding of the glycine inhibitor to the autoproteolytic site of the D151N mutant does not restore the backbone distortion. Therefore, Asp151 plays a dual role, acting as the general base to activate the nucleophile and holding the distorted trans conformation that is critical for initiating an N-O acyl shift.
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Qian
authors.forename: Chudi
authors.initials: C
authors.lastname: Guan
authors.forename: Hwai-Chen
authors.initials: HC
authors.lastname: Guo
mesh_terms: D001224:Aspartic Acid / Q000378:metabolism*; D001227:Aspartylglucosylaminase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011485:Protein Binding; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry
chemical_list: D004792:Enzyme Precursors; D014867:Water; D001224:Aspartic Acid; D001227:Aspartylglucosylaminase; D005998:Glycine