Catalyzes the specific attachment of an amino acid to its cognate tRNA in a two step reaction: the amino acid (AA) is first activated by ATP to form AA-AMP and then transferred to the acceptor end of the tRNA. Exhibits a post-transfer editing activity to hydrolyze mischarged tRNAs. ATP + L-leucine + tRNA(Leu) = AMP + diphosphate + L-leucyl-tRNA(Leu) 5-fluoro-1,3-dihydro-1-hydroxy-1,2-benzoxaborole inhibits LARS1 by forming a covalent adduct with the 3' adenosine of tRNA(Leu) at the editing site, thus locking the enzyme in an inactive conformation. Belongs to the class-I aminoacyl-tRNA synthetase family.