Monellin (MNEI) at 1.15 angstrom resolution

• Type of Material: Article
• Authors: J.R. Hobbs, University of Manchester; S.D. Munger, University of Maryland; Graeme Conn, Emory University
• Language: English
• Date: 2007-03-01
• Publisher: International Union of Crystallography
• Publication Version: Final Published Version
• Copyright Statement: # 2007 International Union of Crystallography All rights reserved
• Final Published Version (URL): http://dx.doi.org/10.1107/S1744309107005271
• Title of Journal or Parent Work: Acta Crystallographica Section F: Structural Biology and Crystallization Communications
• ISSN: 1744-3091
• Volume: 63
• Issue: 3
• Start Page: 162
• End Page: 167
• Grant/Funding Information: This work was supported by funding from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health (DC05786).
• Keywords: THAUMATIN; BIOCHEMISTRY & MOLECULAR BIOLOGY; Crystallography; TASTE; BIOCHEMICAL RESEARCH METHODS; Science & Technology; SOLID-PHASE SYNTHESIS; Physical Sciences; Biochemical Research Methods; BIOPHYSICS; Biophysics; SWEET PROTEIN MONELLIN; Life Sciences & Biomedicine; STABILITY; RECEPTOR; CRYSTALLOGRAPHY; CRYSTAL-STRUCTURE; ACTIVE-SITE; MODELS; Biochemistry & Molecular Biology; SINGLE-CHAIN MONELLIN
• Research Categories: Health Sciences, General; Chemistry, Biochemistry

Abstract

The X-ray crystal structure of a single-chain monellin protein (MNEI) has been determined at 1.15 Å resolution. The model was refined to convergence employing anisotropic displacement parameters and riding H atoms to produce a final model with Rwork and Rfree values of 0.132 and 0.162, respectively. The crystal contains a single MNEI protein in the asymmetric unit and unusually lacks the dimer interface observed in all previous crystal structures of monellin and its single-chain derivatives. The high resolution allowed a more detailed view of MNEI than previously possible, with 38 of the 96 residues modelled with alternative side-chain conformations, including four core residues Thr12, Cys41, Leu62 and Ile75. Four stably bound negative ions were also located, providing new insight into potential electrostatic interactions of MNEI with the largely negatively charged surface of the sweet taste receptor T1R2-T1R3.