3WDR

Crystal structure of beta-mannanase from a symbiotic protist of the termite Reticulitermes speratus complexed with gluco-manno-oligosaccharide

Summary for 3WDR

• Entry DOI: 10.2210/pdb3wdr/pdb
• Related: 3WDQ
• Descriptor: Beta-mannanase, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-alpha-D-mannopyranose, beta-D-glucopyranose-(1-4)-alpha-D-mannopyranose, ... (8 entities in total)
• Functional Keywords: tim barrel, hydrolase, carbohydrate binding
• Biological source: Symbiotic protist of Reticulitermes speratus
• Total number of polymer chains: 1
• Total formula weight: 41961.67

Authors

Tsukagoshi, H.,Ishida, T.,Touhara, K.K.,Igarashi, K.,Samejima, M.,Fushinobu, S.,Kitamoto, K.,Arioka, M. (deposition date: 2013-06-20, release date: 2014-03-05, Last modification date: 2024-04-03)

Primary citation

Tsukagoshi, H.,Nakamura, A.,Ishida, T.,Touhara, K.K.,Otagiri, M.,Moriya, S.,Samejima, M.,Igarashi, K.,Fushinobu, S.,Kitamoto, K.,Arioka, M.
Structural and Biochemical Analyses of Glycoside Hydrolase Family 26 beta-Mannanase from a Symbiotic Protist of the Termite Reticulitermes speratus
J.Biol.Chem., 289:10843-10852, 2014

PubMed Abstract: Termites and their symbiotic protists have established a prominent dual lignocellulolytic system, which can be applied to the biorefinery process. One of the major components of lignocellulose from conifers is glucomannan, which comprises a heterogeneous combination of β-1,4-linked mannose and glucose. Mannanases are known to hydrolyze the internal linkage of the glucomannan backbone, but the specific mechanism by which they recognize and accommodate heteropolysaccharides is currently unclear. Here, we report biochemical and structural analyses of glycoside hydrolase family 26 mannanase C (RsMan26C) from a symbiotic protist of the termite Reticulitermes speratus. RsMan26C was characterized based on its catalytic efficiency toward glucomannan, compared with pure mannan. The crystal structure of RsMan26C complexed with gluco-manno-oligosaccharide(s) explained its specificities for glucose and mannose at subsites -5 and -2, respectively, in addition to accommodation of both glucose and mannose at subsites -3 and -4. RsMan26C has a long open cleft with a hydrophobic platform of Trp(94) at subsite -5, facilitating enzyme binding to polysaccharides. Notably, a unique oxidized Met(85) specifically interacts with the equatorial O-2 of glucose at subsite -3. Our results collectively indicate that specific recognition and accommodation of glucose at the distal negative subsites confers efficient degradation of the heteropolysaccharide by mannanase.

PubMed: 24570006
DOI: 10.1074/jbc.M114.555383

Experimental method

X-RAY DIFFRACTION (1.4 Å)