Mycobacterium tuberculosis strains possess functional cellulases.
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.
Varrot
Annabelle
A
York Structural Biology Laboratory, Department of Chemistry, University of York, York, Y010 5YW, United Kingdom.
Leydier
Sabine
S
Pell
Gavin
G
Macdonald
James M
JM
Stick
Robert V
RV
Henrissat
Bernard
B
Gilbert
Harry J
HJ
Davies
Gideon J
GJ
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
D011134:Polysaccharides; D047071:beta-Glucans; D002482:Cellulose; D044602:Cellulases