Catalyzes the transfer of the alpha-amino group from S-adenosyl-L-methionine (SAM) to 7-keto-8-aminopelargonic acid (KAPA) to form 7,8-diaminopelargonic acid (DAPA). It is the only aminotransferase known to utilize SAM as an amino donor (By similarity). (8S)-8-amino-7-oxononanoate + S-adenosyl-L-methionine = (7R,8S)-7,8-diammoniononanoate + S-adenosyl-4-methylsulfanyl-2-oxobutanoate Cofactor biosynthesis; biotin biosynthesis; 7,8-diaminononanoate from 8-amino-7-oxononanoate (SAM route): step 1/1. Homodimer. Belongs to the class-III pyridoxal-phosphate-dependent aminotransferase family. BioA subfamily.