Involved in self-resistance to cladosporin since this product is an inhibitor of lysyl-tRNA synthetase. Cla4 may not be inhibited by cladosporin, thereby imparting cladosporin resistance (PubMed:26783060). When cladosporin biosynthesis is switched on, transcription of cla4 will then be necessary for continued protein synthesis in C.cladosporioides (PubMed:26783060). ATP + L-lysine + tRNA(Lys) = AMP + diphosphate + L-lysyl-tRNA(Lys) Homodimer. Belongs to the class-II aminoacyl-tRNA synthetase family.