Involved in the biosynthesis of sulfolipids found in thylakoid membranes. Converts UDP-glucose and sulfite to the sulfolipid head group precursor UDP-sulfoquinovose. H(+) + sulfite + UDP-alpha-D-glucose = H2O + UDP-alpha-D-6-sulfoquinovose Concentrations above 100 uM sulfite inhibit the reaction. Optimum pH is 7.5-9.5. Homodimer. Induced in response to altered availability of inorganic phosphate. Belongs to the NAD(P)-dependent epimerase/dehydratase family.