Catalyzes the acyloin condensation reaction between C atoms 2 and 3 of pyruvate and glyceraldehyde 3-phosphate to yield 1-deoxy-D-xylulose-5-phosphate (DXP). D-glyceraldehyde 3-phosphate + H(+) + pyruvate = 1-deoxy-D-xylulose 5-phosphate + CO2 Binds 1 Mg(2+) ion per subunit. Binds 1 thiamine pyrophosphate per subunit. Optimum pH is 7.5-8.0. Optimum temperature is 42-44 degrees Celsius. Metabolic intermediate biosynthesis; 1-deoxy-D-xylulose 5-phosphate biosynthesis; 1-deoxy-D-xylulose 5-phosphate from D-glyceraldehyde 3-phosphate and pyruvate: step 1/1. Homodimer. Belongs to the transketolase family. DXPS subfamily.