Structure of Testis Ace Glycosylation Mutants and Evidence for Conserved Domain Movement.Watermeyer, J.M., Sewell, B.T., Schwager, S.L., Natesh, R., Corradi, H.R., Acharya, K.R., Sturrock, E.D.
(2006) Biochemistry 45: 12654
- PubMed: 17042482
- DOI: 10.1021/bi061146z
- Primary Citation of Related Structures:
- PubMed Abstract:
Human angiotensin-converting enzyme is an important drug target for which little structural information has been available until recent years. The slow progress in obtaining a crystal structure was due to the problem of surface glycosylation, a diffi ...
Human angiotensin-converting enzyme is an important drug target for which little structural information has been available until recent years. The slow progress in obtaining a crystal structure was due to the problem of surface glycosylation, a difficulty that has thus far been overcome by the use of a glucosidase-1 inhibitor in the tissue culture medium. However, the prohibitive cost of these inhibitors and incomplete glucosidase inhibition makes alternative routes to minimizing the N-glycan heterogeneity desirable. Here, glycosylation in the testis isoform (tACE) has been reduced by Asn-Gln point mutations at N-glycosylation sites, and the crystal structures of mutants having two and four intact sites have been solved to 2.0 A and 2.8 A, respectively. Both mutants show close structural identity with the wild-type. A hinge mechanism is proposed for substrate entry into the active cleft, based on homology to human ACE2 at the levels of sequence and flexibility. This is supported by normal-mode analysis that reveals intrinsic flexibility about the active site of tACE. Subdomain II, containing bound chloride and zinc ions, is found to have greater stability than subdomain I in the structures of three ACE homologues. Crystallizable glycosylation mutants open up new possibilities for cocrystallization studies to aid the design of novel ACE inhibitors.
Division of Medical Biochemistry, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa.