Catalyzes 2 different reactions between oxygen and the acireductone 1,2-dihydroxy-3-keto-5-methylthiopentene (DHK-MTPene) depending upon the metal bound in the active site (PubMed:26858196). Fe-containing acireductone dioxygenase (Fe-ARD) produces formate and 2-keto-4-methylthiobutyrate (KMTB), the alpha-ketoacid precursor of methionine in the methionine recycle pathway (PubMed:26858196). Ni-containing acireductone dioxygenase (Ni-ARD) produces methylthiopropionate, carbon monoxide and formate, and does not lie on the methionine recycle pathway (PubMed:26858196). Also down-regulates cell migration mediated by MMP14 (By similarity). 1,2-dihydroxy-5-(methylsulfanyl)pent-1-en-3-one + O2 = 4-methylsulfanyl-2-oxobutanoate + formate + 2 H(+) 1,2-dihydroxy-5-(methylsulfanyl)pent-1-en-3-one + O2 = 3-(methylsulfanyl)propanoate + CO + formate + 2 H(+) Binds either 1 Fe or Ni cation per monomer (PubMed:26858196). Iron-binding promotes an acireductone dioxygenase reaction producing 2-keto-4-methylthiobutyrate, while nickel-binding promotes an acireductone dioxygenase reaction producing 3-(methylsulfanyl)propanoate (PubMed:26858196). kcat is 114.3 sec(-1) with 1,2-dihydroxy-5-(methylsulfanyl)pent-1-en-3-one as substrate (using iron as cofactor) (PubMed:26858196). kcat is 7.55 sec(-1) with 1,2-dihydroxy-5-(methylsulfanyl)pent-1-en-3-one as substrate (using cobalt as cofactor) (PubMed:26858196). kcat is 17.7 sec(-1) with 1,2-dihydroxy-5-(methylsulfanyl)pent-1-en-3-one as substrate (using nickel as cofactor) (PubMed:26858196). Amino-acid biosynthesis; L-methionine biosynthesis via salvage pathway; L-methionine from S-methyl-5-thio-alpha-D-ribose 1-phosphate: step 5/6. Monomer. Interacts with MMP14. Localizes to the plasma membrane when complexed to MMP14. Belongs to the acireductone dioxygenase (ARD) family.