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. The disease is caused by variants affecting the gene represented in this entry. Belongs to the class-I aminoacyl-tRNA synthetase family. Extended N-terminus.