Involved in the gluconeogenesis. Catalyzes stereospecifically the conversion of dihydroxyacetone phosphate (DHAP) to D-glyceraldehyde-3-phosphate (G3P). D-glyceraldehyde 3-phosphate = dihydroxyacetone phosphate kcat is 54000 min(-1) for isomerase activity with D-glyceraldehyde 3-phosphate as substrate (at 25 degrees Celsius). Carbohydrate biosynthesis; gluconeogenesis. Carbohydrate degradation; glycolysis; D-glyceraldehyde 3-phosphate from glycerone phosphate: step 1/1. Homodimer. Induced by CsrA and repressed by spermidine. Cells lacking this gene accumulates methylglyoxal and are unable to grow on glucose, lactate or other carbon sources. Belongs to the triosephosphate isomerase family.