Crystal Structure of Human Arginase l at 1.29-Angstrom Resolution and Exploration of Inhibition in the Immune Response

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Proc Natl Acad Sci USA

DOI:https://doi.org/10.1073/pnas.0504027102· OSTI ID:913773

Di Costanzo, L; Sabio, G; Mora, A; Rodriguez, P; Ochoa, A; Centeno, F; Christianson, D

Human arginase I is a potential target for therapeutic intervention in diseases linked to compromised L-arginine homeostasis. Here, we report high-affinity binding of the reaction coordinate analogue inhibitors 2(S)-amino-6-boronohexanoic acid (ABH, Kd = 5 nM) and S-(2-boronoethyl)-L-cysteine (BEC, Kd = 270 nM) to human arginase I, and we report x-ray crystal structures of the respective enzyme-inhibitor complexes at 1.29- and 1.94-Angstrom resolution determined from crystals twinned by hemihedry. The ultrahigh-resolution structure of the human arginase I-ABH complex yields an unprecedented view of the binuclear manganese cluster and illuminates the structural basis for nanomolar affinity: bidentate inner-sphere boronate-manganese coordination interactions and fully saturated hydrogen bond networks with inhibitor {alpha}-amino and {alpha}-carboxylate groups. These interactions are therefore implicated in the stabilization of the transition state for L-arginine hydrolysis. Electron density maps also reveal that active-site residue H141 is protonated as the imidazolium cation. The location of H141 is such that it could function as a general acid to protonate the leaving amino group of L-ornithine during catalysis, and this is a revised mechanistic proposal for arginase. This work serves as a foundation for studying the structural and chemical biology of arginase I in the immune response, and we demonstrate the inhibition of arginase activity by ABH in human and murine myeloid cells.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 913773
• Report Number(s): BNL--78341-2007-JA
• Journal Information: Proc Natl Acad Sci USA, Journal Name: Proc Natl Acad Sci USA Journal Issue: 37 Vol. 102; ISSN 0027-8424; ISSN PNASA6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ARGINASE
CRYSTAL STRUCTURE
ELECTRON DENSITY
EXPLORATION
IMMUNE REACTIONS
RESOLUTION
national synchrotron light source