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Title: Computational Investigation of Glycosylation Effects on a Family 1 Carbohydrate-Binding Module

Abstract

Carbohydrate-binding modules (CBMs) are ubiquitous components of glycoside hydrolases, which degrade polysaccharides in nature. CBMs target specific polysaccharides, and CBM binding affinity to cellulose is known to be proportional to cellulase activity, such that increasing binding affinity is an important component of performance improvement. To ascertain the impact of protein and glycan engineering on CBM binding, we use molecular simulation to quantify cellulose binding of a natively glycosylated Family 1 CBM. To validate our approach, we first examine aromatic-carbohydrate interactions on binding, and our predictions are consistent with previous experiments, showing that a tyrosine to tryptophan mutation yields a 2-fold improvement in binding affinity. We then demonstrate that enhanced binding of 3-6-fold over a nonglycosylated CBM is achieved by the addition of a single, native mannose or a mannose dimer, respectively, which has not been considered previously. Furthermore, we show that the addition of a single, artificial glycan on the anterior of the CBM, with the native, posterior glycans also present, can have a dramatic impact on binding affinity in our model, increasing it up to 140-fold relative to the nonglycosylated CBM. These results suggest new directions in protein engineering, in that modifying glycosylation patterns via heterologous expression, manipulation ofmore » culture conditions, or introduction of artificial glycosylation sites, can alter CBM binding affinity to carbohydrates and may thus be a general strategy to enhance cellulase performance. Our results also suggest that CBM binding studies should consider the effects of glycosylation on binding and function.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy Biomass Program; National Science Foundation (NSF); National Energy Research Scientific Computing Center
OSTI Identifier:
1047941
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Journal of Biological Chemistry
Additional Journal Information:
Journal Volume: 287; Journal Issue: 5; Journal ID: ISSN 0021-9258
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 59 BASIC BIOLOGICAL SCIENCES; AFFINITY; BIOMASS; CARBOHYDRATES; CELLULASE; CELLULOSE; COMPUTERS; GLYCOPROTEINS; GLYCOSIDES; HYDROLASES; MANNOSE; MUTATIONS; POLYSACCHARIDES; PROTEIN ENGINEERING; PROTEINS; TARGETS; THERMODYNAMICS; TRICHODERMA VIRIDE; TRYPTOPHAN; TYROSINE; Bioenergy; Chemical and Biosciences

Citation Formats

Taylor, C. B., Talib, M. F., McCabe, C., Bu, L., Adney, W. S., Himmel, M. E., Crowley, M. F., and Beckham, G. T. Computational Investigation of Glycosylation Effects on a Family 1 Carbohydrate-Binding Module. United States: N. p., 2012. Web. doi:10.1074/jbc.M111.270389.
Taylor, C. B., Talib, M. F., McCabe, C., Bu, L., Adney, W. S., Himmel, M. E., Crowley, M. F., & Beckham, G. T. Computational Investigation of Glycosylation Effects on a Family 1 Carbohydrate-Binding Module. United States. doi:10.1074/jbc.M111.270389.
Taylor, C. B., Talib, M. F., McCabe, C., Bu, L., Adney, W. S., Himmel, M. E., Crowley, M. F., and Beckham, G. T. Fri . "Computational Investigation of Glycosylation Effects on a Family 1 Carbohydrate-Binding Module". United States. doi:10.1074/jbc.M111.270389.
@article{osti_1047941,
title = {Computational Investigation of Glycosylation Effects on a Family 1 Carbohydrate-Binding Module},
author = {Taylor, C. B. and Talib, M. F. and McCabe, C. and Bu, L. and Adney, W. S. and Himmel, M. E. and Crowley, M. F. and Beckham, G. T.},
abstractNote = {Carbohydrate-binding modules (CBMs) are ubiquitous components of glycoside hydrolases, which degrade polysaccharides in nature. CBMs target specific polysaccharides, and CBM binding affinity to cellulose is known to be proportional to cellulase activity, such that increasing binding affinity is an important component of performance improvement. To ascertain the impact of protein and glycan engineering on CBM binding, we use molecular simulation to quantify cellulose binding of a natively glycosylated Family 1 CBM. To validate our approach, we first examine aromatic-carbohydrate interactions on binding, and our predictions are consistent with previous experiments, showing that a tyrosine to tryptophan mutation yields a 2-fold improvement in binding affinity. We then demonstrate that enhanced binding of 3-6-fold over a nonglycosylated CBM is achieved by the addition of a single, native mannose or a mannose dimer, respectively, which has not been considered previously. Furthermore, we show that the addition of a single, artificial glycan on the anterior of the CBM, with the native, posterior glycans also present, can have a dramatic impact on binding affinity in our model, increasing it up to 140-fold relative to the nonglycosylated CBM. These results suggest new directions in protein engineering, in that modifying glycosylation patterns via heterologous expression, manipulation of culture conditions, or introduction of artificial glycosylation sites, can alter CBM binding affinity to carbohydrates and may thus be a general strategy to enhance cellulase performance. Our results also suggest that CBM binding studies should consider the effects of glycosylation on binding and function.},
doi = {10.1074/jbc.M111.270389},
journal = {Journal of Biological Chemistry},
issn = {0021-9258},
number = 5,
volume = 287,
place = {United States},
year = {2012},
month = {1}
}