Uses 5-methylthioribulose-1-phosphate to yield 2-(methylthio)acetaldehyde and dihydroxyacetone phosphate (PubMed:29133429, PubMed:31950558). Can also use 5-deoxyribulose 1-phosphate to yield acetaldehyde and dihydroxyacetone phosphate (PubMed:31950558). Part of a bifunctional DHAP-shunt salvage pathway for SAM by-products (PubMed:31950558). S-methyl-5-thio-D-ribulose 1-phosphate = 2-(methylsulfanyl)acetaldehyde + dihydroxyacetone phosphate 5-deoxy-D-ribulose 1-phosphate = acetaldehyde + dihydroxyacetone phosphate Binds 1 cobalt ion per subunit (By similarity). Can also use Ni(2+) (PubMed:31950558). kcat is 0.94 sec(-1) with 5-methylthioribulose-1-phosphate as substrate. kcat is 1.94 sec(-1) with 5-deoxyribulose 1-phosphate as substrate. kcat is 0.44 sec(-1) with ribulose-1-phosphate as substrate. Amino-acid biosynthesis; L-methionine biosynthesis via salvage pathway. Mutants produce only low levels of ethylene when grown on MTA (PubMed:29133429). Deletion mutant accumulates both S-methyl-5'-thioadenosine and 5'-deoxyadenosine extracellularly (PubMed:31950558). Belongs to the aldolase class II family.