Structural studies of plant UDP-arabinopyranose mutases

The widespread presence of L-arabinofuranose (Araf) in the plant cell wall has long been recognized, but its biosynthesis from UDP-arabinopyranose (UDP-Arap) remained enigmatic. With the very recent discovery of UDP-Araf transporters in the Golgi membrane, it has become clear that the cytosolic UDP-arabinopyranose mutases (UAMs) are likely to be the key enzymes converting UDP-Arap to UDP-Araf for cell wall biosynthesis. UAM is a relatively newly discovered activity in the plant cytosol, and the enzymatic mechanism and other molecular features such as protein structure and oligomeric state are unknown. Here, we pursue the structural elucidation of rice UAMs by X-ray crystallography