Mechanisms Governing Precise Protein Biotinylation. Issue 5 (May 2017)

• Record Type: Journal Article
• Authors: Sternicki, Louise M.; Wegener, Kate L.; Bruning, John B.; Booker, Grant W.; Polyak, Steven W.
• Is Part Of: Trends in biochemical sciences. Volume 42:Issue 5(2017)
• Page Start: 383
• Page End: 394
• Publication Date: 2017-05
• Subjects: Biochemistry -- Periodicals; 572
• DOI: 10.1016/j.tibs.2017.02.001
• Languages: English
• ISSNs: 0968-0004

Abstract

Abstract : Protein biotinylation is a key post-translational modification found throughout the living world. The covalent attachment of a biotin cofactor onto specific metabolic enzymes is essential for their activity. This modification is distinctive, in that it is carried out by a single enzyme: biotin protein ligase (BPL), an enzyme that is able to biotinylate multiple target substrates without aberrant-off target biotinylation. BPL achieves this target selectivity by recognizing a sequence motif in the context of a highly conserved tertiary structure. One structural class of BPLs has developed an additional 'substrate verification' mechanism to further enable appropriate protein selection. This is crucial for the precise and selective biotinylation required for efficient biotin management, especially in organisms that are auxotrophic for biotin. Trends: BPL catalyzes the exquisitely precise attachment of biotin onto protein substrate(s). Structural biology has helped to provide powerful new insights into the molecular basis of protein biotinylation. BPL recognizes a consensus AMKM motif in the protein substrate within the context of a flattened β-barrel tertiary structure. This tertiary structure is conserved amongst all biotin-dependent enzymes. This allows one enzyme, BPL, to modify multiple substrates within one organism, and without erroneously biotinylating off-target proteins. Mammalian BPLs can discriminate between protein substrates. This allows these biotin auxotrophs to effectively utilize the precious micronutrient. A unique N-terminal extension on mammalian BPLs enhances catalytic activity by providing stabilizing interactions with substrates. It is proposed that the interactions generated by this domain may allow 'substrate verification' to select appropriate proteins for modification.