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Molecular basis for the selectivity and specificity of ligand recognition by the family 16 carbohydrate-binding modules from Thermoanaerobacterium polysaccharolyticum ManA
Journal article   Open access   Peer reviewed

Molecular basis for the selectivity and specificity of ligand recognition by the family 16 carbohydrate-binding modules from Thermoanaerobacterium polysaccharolyticum ManA

Brian Bae, Samuel Ohene-Adjei, Svetlana Kocherginskaya, Roderick I. Mackie, M. Ashley Spies, Isaac K. O. Cann and Satish K. Nair
The Journal of biological chemistry, Vol.283(18), pp.12415-12425
05/02/2008
DOI: 10.1074/jbc.M706513200
PMID: 18025086
url
https://doi.org/10.1074/jbc.M706513200View
Published (Version of record) Open Access

Abstract

Enzymes that hydrolyze complex polysaccharides into simple sugars are modular in architecture and consist of single or multiple catalytic domains fused to targeting modules called carbohydratebinding modules (CBMs). CBMs bind to their ligands with high affinity and increase the efficiency of the catalytic components by targeting the enzymes to its substrate. Here we utilized a multidisciplinary approach to characterize each of the two family 16 carbohydrate-binding domain components of the highly active mannanase from the thermophile Thermoanaerobacterium polysaccharolyticum. These represent the first crystal structures of family 16 CBMs. Calorimetric analysis showed that although these CBMs demonstrate high specificity toward beta-1,4-linked sugars, they can engage both cello- and manno-polysaccharides. To elucidate the molecular basis for this specificity and selectivity, we have determined high resolution crystal structures of each of the two CBMs, as well as of binary complexes of CBM16-1 bound to either mannopentaose or cellopentaose. These results provide detailed molecular insights into ligand recognition and yield a framework for rational engineering experiments designed to expand the natural repertoire of these targeting modules.
Biochemistry & Molecular Biology Life Sciences & Biomedicine Science & Technology

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