title: Characterization of benzoxaborole-based antifungal resistance mutations demonstrates that editing depends on electrostatic stabilization of the leucyl-tRNA synthetase editing cap.
abstract: The broad-spectrum benzoxaborole antifungal AN2690 blocks protein synthesis by inhibiting leucyl-tRNA synthetase (LeuRS) via a novel oxaborole tRNA trapping mechanism in the editing site. Herein, one set of resistance mutations is at Asp487 outside the LeuRS hydrolytic editing pocket, in a region of unknown function. It is located within a eukaryote/archaea specific insert I4, which forms part of a cap over a benzoxaborole-AMP that is bound in the LeuRS CP1 domain editing active site. Mutational and biochemical analysis at Asp487 identified a salt bridge between Asp487 and Arg316 in the hinge region of the I4 cap of yeast LeuRS that is critical for tRNA deacylation. We hypothesize that this electrostatic interaction stabilizes the cap during binding of the editing substrate for hydrolysis.
authors.affiliation: Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Jaya
authors.initials: J
authors.lastname: Sarkar
authors.forename: Weimin
authors.initials: W
authors.lastname: Mao
authors.forename: Tommie L
authors.initials: TL
authors.lastname: Lincecum
authors.forename: M R K
authors.initials: MR
authors.lastname: Alley
authors.forename: Susan A
authors.initials: SA
authors.lastname: Martinis
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D001896:Boron Compounds / Q000737:chemistry / Q000378:metabolism*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry / Q000378:metabolism*; D004252:DNA Mutational Analysis; D025141:Drug Resistance, Fungal / Q000235:genetics*; D007935:Leucine-tRNA Ligase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017434:Protein Structure, Tertiary; D012315:RNA Caps / Q000737:chemistry*; D017393:RNA Editing; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D055672:Static Electricity
chemical_list: D000935:Antifungal Agents; D001896:Boron Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D012315:RNA Caps; D007935:Leucine-tRNA Ligase; C512998:tavaborole