3U5U

Structures of Alkaloid Biosynthetic Glucosidases Decode Substrate Specificity

Summary for 3U5U

• Entry DOI: 10.2210/pdb3u5u/pdb
• Related: 3U57 3U5Y
• Descriptor: Raucaffricine-O-beta-D-glucosidase, CHLORIDE ION (3 entities in total)
• Functional Keywords: raucaffricine glucosidase (rg), hydrolase
• Biological source: Rauvolfia serpentina (devilpepper)
• Total number of polymer chains: 2
• Total formula weight: 115733.61

Authors

Xia, L.,Ruppert, M.,Wang, M.,Panjikar, S.,Lin, H.,Rajendran, C.,Barleben, L.,Stoeckigt, J. (deposition date: 2011-10-11, release date: 2011-11-30, Last modification date: 2024-03-20)

Primary citation

Xia, L.,Ruppert, M.,Wang, M.,Panjikar, S.,Lin, H.,Rajendran, C.,Barleben, L.,Stockigt, J.
Structures of alkaloid biosynthetic glucosidases decode substrate specificity.
Acs Chem.Biol., 7:226-234, 2012

PubMed Abstract: Two similar enzymes with different biosynthetic function in one species have evolved to catalyze two distinct reactions. X-ray structures of both enzymes help reveal their most important differences. The Rauvolfia alkaloid biosynthetic network harbors two O-glucosidases: raucaffricine glucosidase (RG), which hydrolyses raucaffricine to an intermediate downstream in the ajmaline pathway, and strictosidine glucosidase (SG), which operates upstream. RG converts strictosidine, the substrate of SG, but SG does not accept raucaffricine. Now elucidation of crystal structures of RG, inactive RG-E186Q mutant, and its complexes with ligands dihydro-raucaffricine and secologanin reveals that it is the "wider gate" of RG that allows strictosidine to enter the catalytic site, whereas the "slot-like" entrance of SG prohibits access by raucaffricine. Trp392 in RG and Trp388 in SG control the gate shape and acceptance of substrates. Ser390 directs the conformation of Trp392. 3D structures, supported by site-directed mutations and kinetic data of RG and SG, provide a structural and catalytic explanation of substrate specificity and deeper insights into O-glucosidase chemistry.

PubMed: 22004291
DOI: 10.1021/cb200267w

Experimental method

X-RAY DIFFRACTION (2.2 Å)