title: Recognition of the helical structure of beta-1,4-galactan by a new family of carbohydrate-binding modules.
abstract: The microbial enzymes that depolymerize plant cell wall polysaccharides, ultimately promoting energy liberation and carbon recycling, are typically complex in their modularity and often contain carbohydrate-binding modules (CBMs). Here, through analysis of an unknown module from a Thermotoga maritima endo-β-1,4-galactanase, we identify a new family of CBMs that are most frequently found appended to proteins with β-1,4-galactanase activity. Polysaccharide microarray screening, immunofluorescence microscopy, and biochemical analysis of the isolated module demonstrate the specificity of the module, here called TmCBM61, for β-1,4-linked galactose-containing ligands, making it the founding member of family CBM61. The ultra-high resolution X-ray crystal structures of TmCBM61 (0.95 and 1.4 Å resolution) in complex with β-1,4-galactotriose reveal the molecular basis of the specificity of the CBM for β-1,4-galactan. Analysis of these structures provides insight into the recognition of an unexpected helical galactan conformation through a mode of binding that resembles the recognition of starch.
authors.affiliation: Department Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.
authors.forename: Melissa
authors.initials: M
authors.lastname: Cid
authors.forename: Henriette Lodberg
authors.initials: HL
authors.lastname: Pedersen
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kaneko
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Coutinho
authors.forename: Bernard
authors.initials: B
authors.lastname: Henrissat
authors.forename: William G T
authors.initials: WG
authors.lastname: Willats
authors.forename: Alisdair B
authors.initials: AB
authors.lastname: Boraston
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry; D018360:Crystallography, X-Ray; D005685:Galactans / Q000737:chemistry / Q000378:metabolism*; D005690:Galactose / Q000737:chemistry / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046228:Microarray Analysis; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020124:Thermotoga maritima / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D002241:Carbohydrates; D005685:Galactans; D009844:Oligosaccharides; D011134:Polysaccharides; D006026:Glycoside Hydrolases; C094192:arabinogalactan endo-1,4-beta-galactosidase; D005690:Galactose
references.citation: J Biol Chem. 2008 Nov 14;283(46):31279-83
references.pmid: 18784084
references.citation: J Mol Biol. 2007 Apr 6;367(4):1023-33
references.pmid: 17292916
references.citation: Structure. 2008 Jul;16(7):1105-15
references.pmid: 18611383
references.citation: Proc Natl Acad Sci U S A. 2009 Mar 3;106(9):3065-70
references.pmid: 19218457
references.citation: Acta Crystallogr D Biol Crystallogr. 2002 Oct;58(Pt 10 Pt 2):1772-9
references.pmid: 12351820
references.citation: J Mol Biol. 2005 Mar 25;347(2):287-96
references.pmid: 15740741
references.citation: J Biol Chem. 2006 Jan 6;281(1):587-98
references.pmid: 16230347
references.citation: Structure. 2005 Oct;13(10):1453-62
references.pmid: 16216577
references.citation: Glycoconj J. 2008 Jan;25(1):37-48
references.pmid: 17629746
references.citation: Nature. 1992 Jan 30;355(6359):472-5
references.pmid: 18481394
references.citation: Structure. 2004 Jul;12(7):1177-87
references.pmid: 15242594
references.citation: Biosci Biotechnol Biochem. 2006 Feb;70(2):538-41
references.pmid: 16495677
references.citation: Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 1):2126-32
references.pmid: 15572765
references.citation: Biochem J. 2004 Sep 15;382(Pt 3):769-81
references.pmid: 15214846
references.citation: J Biol Chem. 2010 Oct 8;285(41):31742-54
references.pmid: 20659893
references.citation: J Mol Biol. 2007 Jan 19;365(3):555-60
references.pmid: 17095014
references.citation: Acta Crystallogr D Biol Crystallogr. 2006 Aug;62(Pt 8):901-8
references.pmid: 16855307
references.citation: Plant Physiol. 1997 Apr;113(4):1405-1412
references.pmid: 12223681
references.citation: Proc Natl Acad Sci U S A. 1999 Apr 13;96(8):4246-51
references.pmid: 10200247
references.citation: Acta Crystallogr D Biol Crystallogr. 1997 May 1;53(Pt 3):240-55
references.pmid: 15299926
references.citation: J Biol Chem. 2008 May 2;283(18):12604-13
references.pmid: 18292090
references.citation: Acta Crystallogr D Biol Crystallogr. 1999 Jan;55(Pt 1):191-205
references.pmid: 10089410
references.citation: Acta Crystallogr D Biol Crystallogr. 1999 Oct;55(Pt 10):1690-5
references.pmid: 10531518
references.citation: Biochem J. 1998 May 1;331 ( Pt 3):775-81
references.pmid: 9560304
references.citation: Plant Mol Biol. 2001 Sep;47(1-2):9-27
references.pmid: 11554482
references.citation: Mol Microbiol. 2010 Jul 1;77(1):183-99
references.pmid: 20497336
references.citation: Acta Crystallogr D Biol Crystallogr. 2002 Jun;58(Pt 6 Pt 2):976-91
references.pmid: 12037300
references.citation: Nucleic Acids Res. 2003 Jul 1;31(13):3784-8
references.pmid: 12824418
references.citation: Planta. 2004 Feb;218(4):673-81
references.pmid: 14618325
references.citation: J Biol Chem. 2006 Nov 17;281(46):35263-71
references.pmid: 16987809
references.citation: J Biol Chem. 2005 Jan 7;280(1):530-7
references.pmid: 15501830
references.citation: Curr Opin Plant Biol. 2008 Jun;11(3):338-48
references.pmid: 18430603
references.citation: Proteins. 2009 Jun;75(4):977-89
references.pmid: 19089956
references.citation: J Biol Chem. 2001 Dec 21;276(51):48580-7
references.pmid: 11673472
references.citation: J Appl Crystallogr. 2007 Aug 1;40(Pt 4):658-674
references.pmid: 19461840
references.citation: J Biol Chem. 2006 Dec 8;281(49):37748-57
references.pmid: 16990278
references.citation: Nat Struct Mol Biol. 2007 Jan;14(1):76-84
references.pmid: 17187076
references.citation: Biochemistry. 2001 Dec 4;40(48):14679-85
references.pmid: 11724582
references.citation: Prog Biophys Mol Biol. 1999;72(3):245-70
references.pmid: 10581970
references.citation: Can J Biochem Cell Biol. 1984 May;62(5):270-5
references.pmid: 6733568
references.citation: Anal Biochem. 2004 Mar 1;326(1):49-54
references.pmid: 14769335
references.citation: J Biol Chem. 2008 May 2;283(18):12415-25
references.pmid: 18025086
references.citation: Nat Struct Biol. 1999 May;6(5):458-63
references.pmid: 10331874
references.citation: Biochemistry. 2003 Aug 12;42(31):9316-23
references.pmid: 12899618