Uses 5-methylthioribulose-1-phosphate to yield 2-(methylthio)acetaldehyde and dihydroxyacetone phosphate. Can also use 5-deoxyribulose 1-phosphate to yield acetaldehyde and dihydroxyacetone phosphate. Part of a bifunctional DHAP-shunt salvage pathway for SAM by-products. 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 Mn(2+) (PubMed:31950558). kcat is 22 sec(-1) with 5-methylthioribulose-1-phosphate as substrate. kcat is 22 sec(-1) with 5-deoxyribulose 1-phosphate as substrate. kcat is 8.7 sec(-1) with ribulose-1-phosphate as substrate. Amino-acid biosynthesis; L-methionine biosynthesis via salvage pathway. Inactivation of the gene precludes growth of the strain with 5-deoxyribose. Belongs to the aldolase class II family.