Pyridoxal phosphate (PLP)-dependent transaminase involved in the biosynthesis of amidated D-glucuronic acid structures found on the capsular polysaccharide (CPS) of C.jejuni. Catalyzes the transamination of dihydroxyacetone phosphate (DHAP) to (S)-serinol phosphate in the presence of L-glutamate. Less active with L-aspartate. No activity with dihydroxyacetone or L-alanine. dihydroxyacetone phosphate + L-glutamate = (S)-serinol phosphate + 2-oxoglutarate kcat is 0.50 sec(-1) with DHAP as substrate. Capsule biogenesis; capsule polysaccharide biosynthesis. The reaction product of this enzyme, serinol phosphate, is an important precursor for serinol (2-amino-1,3-propanediol) production. Serinol, in turn, is an intermediate in the formation of certain drugs, such as the anti-cancer N-palmitoyl-2-amino-1,3-propanediol, and the orally administered fingolimod (sold under the brand name Gilenya) to treat multiple sclerosis. Belongs to the class-II pyridoxal-phosphate-dependent aminotransferase family.