Involved in the biosynthesis of the coenzyme M (2-mercaptoethanesulfonic acid). Catalyzes the decarboxylation of sulfopyruvate to sulfoacetaldehyde. Is not able to decarboxylate the analogous compounds 2-oxoglutarate or 2-oxosuberate. 3-sulfopyruvate + H(+) = CO2 + sulfoacetaldehyde Binds 1 thiamine pyrophosphate per subunit. Cofactor biosynthesis; coenzyme M biosynthesis. Belongs to the TPP enzyme family.