title: Mycobacterium tuberculosis strains possess functional cellulases.
abstract: The genomes of various Mycobacterium tuberculosis strains encode proteins that do not appear to play a role in the growth or survival of the bacterium in its mammalian host, including some implicated in plant cell wall breakdown. Here we show that M. tuberculosis H37Rv does indeed possess a functional cellulase. The x-ray crystal structure of this enzyme, in ligand complex forms, from 1.9 to 1.1A resolution, reveals a highly conserved substrate-binding cleft, which affords similar, and unusual, distortion of the substrate at the catalytic center. The endoglucanase activity, together with the existence of a putative membrane-associated crystalline polysaccharide-binding protein, may reflect the ancestral soil origin of the Mycobacterium or hint at a previously unconsidered environmental niche.
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York, Y010 5YW, United Kingdom.
authors.forename: Annabelle
authors.initials: A
authors.lastname: Varrot
authors.forename: Sabine
authors.initials: S
authors.lastname: Leydier
authors.forename: Gavin
authors.initials: G
authors.lastname: Pell
authors.forename: James M
authors.initials: JM
authors.lastname: Macdonald
authors.forename: Robert V
authors.initials: RV
authors.lastname: Stick
authors.forename: Bernard
authors.initials: B
authors.lastname: Henrissat
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Gilbert
authors.forename: Gideon J
authors.initials: GJ
authors.lastname: Davies
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D044602:Cellulases / Q000737:chemistry / Q000502:physiology*; D002482:Cellulose / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D010802:Phylogeny; D011134:Polysaccharides / Q000378:metabolism; D017433:Protein Structure, Secondary; D012988:Soil Microbiology; D013379:Substrate Specificity; D047071:beta-Glucans / Q000378:metabolism
chemical_list: D011134:Polysaccharides; D047071:beta-Glucans; D002482:Cellulose; D044602:Cellulases