Content area
Full Text
J Biomol NMR (2015) 61:137150 DOI 10.1007/s10858-014-9895-2
ARTICLE
Comparison of backbone dynamics of the type III antifreeze protein and antifreeze-like domain of human sialic acid synthase
Yong-Geun Choi Chin-Ju Park Hee-Eun Kim
Yeo-Jin Seo Ae-Ree Lee Seo-Ree Choi
Shim Sung Lee Joon-Hwa Lee
Received: 2 November 2014 / Accepted: 30 December 2014 / Published online: 10 January 2015 Springer Science+Business Media Dordrecht 2015
Abstract Antifreeze proteins (AFPs) are found in a variety of cold-adapted (psychrophilic) organisms to promote survival at subzero temperatures by binding to ice crystals and decreasing the freezing temperature of body uids. The type III AFPs are small globular proteins that consist of one a-helix, three 310-helices, and two b-strands.
Sialic acids play important roles in a variety of biological functions, such as development, recognition, and cell adhesion and are synthesized by conserved enzymatic pathways that include sialic acid synthase (SAS). SAS consists of an N-terminal catalytic domain and a C-terminal antifreeze-like (AFL) domain, which is similar to the type III AFPs. Despite having very similar structures, AFL and the type III AFPs exhibit very different temperature-dependent stability and activity. In this study, we have performed backbone dynamics analyses of a type III AFP
(HPLC12 isoform) and the AFL domain of human SAS (hAFL) at various temperatures. We also characterized the structural/dynamic properties of the ice-binding surfaces by analyzing the temperature gradient of the amide proton chemical shift and its correlation with chemical shift deviation from random coil. The dynamic properties of the two proteins were very different from each other. While HPLC12 was mostly rigid with a few residues exhibiting slow motions, hAFL showed fast internal motions at low temperature. Our results provide insight into the molecular basis of thermostability and structural exibility in homologous psychrophilic HPLC12 and mesophilic hAFL proteins.
Keywords NMR Backbone dynamics Antifreeze
protein Antifreeze-like protein Ice-binding protein
AbbreviationsAFP Antifreeze proteinQAE Quaternary-amino-ethylSP SulfopropylTH Thermal hysteresisIBS Ice-binding surfaceAFL Domain antifreeze-like domain Sialic acid N-acetylneuraminic acidSAS Sialic acid synthasePEP Phosphoenolpyruvate ManNAc N-acetylmannosamine NeuNAc N-acetylneuraminic acid ManNAc-6P ManNAc 6-phosphate NeuNAc-9P NeuNAc 9-phosphate3D Three-dimensionalCSD Chemical shift deviation H-bond Hydrogen-bondNOE Nuclear Overhauser effect
Yong-Geun Choi and Chin-Ju Park have contributed equally to this work.
Electronic supplementary material The online version of this article (doi:http://dx.doi.org/10.1007/s10858-014-9895-2
Web End =10.1007/s10858-014-9895-2 ) contains supplementary material, which is...