Catalysis of the reaction: ATP + UDP-N-acetylmuramoyl-L-alanyl-D-glutamyl-meso-2,6-diaminoheptanedioate + D-alanyl-D-alanine = ADP + phosphate + UDP-N-acetylmuramoyl-L-alanyl-D-glutamyl-6-carboxy-L-lysyl-D-alanyl-D-alanine
Comment
Note that EC:6.3.2.15 was deleted from EC as the reaction is performed by UDP-N-acetylmuramoyl-tripeptide-D-alanyl-D-alanine ligase (EC:6.3.2.10).