title: Biotinylation, a post-translational modification controlled by the rate of protein-protein association.
abstract: Biotin protein ligases catalyze specific covalent linkage of the coenzyme biotin to biotin-dependent carboxylases. The reaction proceeds in two steps, including synthesis of an adenylated intermediate followed by biotin transfer to the carboxylase substrate. In this work specificity in the transfer reaction was investigated using single turnover stopped-flow and quench-flow assays. Cognate and noncognate reactions were measured using the enzymes and minimal biotin acceptor substrates from Escherichia coli, Pyrococcus horikoshii, and Homo sapiens. The kinetic analysis demonstrates that for all enzyme-substrate pairs the bimolecular rate of association of enzyme with substrate limits post-translational biotinylation. In addition, in noncognate reactions the three enzymes displayed a range of selectivities. These results highlight the importance of protein-protein binding kinetics for specific biotin addition to carboxylases and provide one mechanism for determining biotin distribution in metabolism.
authors.affiliation: Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Ingaramo
authors.forename: Dorothy
authors.initials: D
authors.lastname: Beckett
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism*; D019921:Biotinylation / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D011485:Protein Binding / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D043902:Pyrococcus horikoshii / Q000235:genetics / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D029968:Escherichia coli Proteins