1L9M

Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions change structure for activation

Summary for 1L9M

• Entry DOI: 10.2210/pdb1l9m/pdb
• Related: 1L9M 1L9N
• Descriptor: Protein-glutamine glutamyltransferase E3, BROMIDE ION, CHLORIDE ION, ... (5 entities in total)
• Functional Keywords: activation, calcium binding, transglutaminase, transferase
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 2
• Total formula weight: 153651.87

Authors

Ahvazi, B. (deposition date: 2002-03-26, release date: 2002-05-29, Last modification date: 2023-08-16)

Primary citation

Ahvazi, B.,Kim, H.C.,Kee, S.H.,Nemes, Z.,Steinert, P.M.
Three-dimensional structure of the human transglutaminase 3 enzyme: binding of calcium ions changes structure for activation.
EMBO J., 21:2055-2067, 2002

PubMed Abstract: Transglutaminase (TGase) enzymes catalyze the formation of covalent cross-links between protein-bound glutamines and lysines in a calcium-dependent manner, but the role of Ca(2+) ions remains unclear. The TGase 3 isoform is widely expressed and is important for epithelial barrier formation. It is a zymogen, requiring proteolysis for activity. We have solved the three-dimensional structures of the zymogen and the activated forms at 2.2 and 2.1 A resolution, respectively, and examined the role of Ca(2+) ions. The zymogen binds one ion tightly that cannot be exchanged. Upon proteolysis, the enzyme exothermally acquires two more Ca(2+) ions that activate the enzyme, are exchangeable and are functionally replaceable by other lanthanide trivalent cations. Binding of a Ca(2+) ion at one of these sites opens a channel which exposes the key Trp236 and Trp327 residues that control substrate access to the active site. Together, these biochemical and structural data reveal for the first time in a TGase enzyme that Ca(2+) ions induce structural changes which at least in part dictate activity and, moreover, may confer substrate specificity.

PubMed: 11980702
DOI: 10.1093/emboj/21.9.2055

Experimental method

X-RAY DIFFRACTION (2.1 Å)