Tandem repeat of a seven-bladed beta-propeller domain in oligoxyloglucan reducing-end-specific cellobiohydrolase.
Oligoxyloglucan reducing-end-specific cellobiohydrolase (OXG-RCBH; EC 3.2.1.150) is an exoglucanase that recognizes the reducing end of oligoxyloglucan and releases two glucosyl residue segments from the main chain. The X-ray crystal structure of OXG-RCBH determined at 2.2 A resolution reveals a unique feature of this enzyme; OXG-RCBH consists of a tandem repeat of two similar domains, which are both folded into seven-bladed beta-propeller structures. The sequence alignment of the propeller blades, based on the structure, indicates that a weak repeat of the amino acid sequence occurred seven times to construct each domain. There is a cleft that can accommodate the substrate oligosaccharide between the two domains, which is a putative substrate binding subsite. Mutation of either Asp35 or Asp465, located in the putative catalytic center, to Asn resulted in a protein with no detectable catalytic activity, indicating the critical role of these amino acids in catalysis.
Yaoi
Katsuro
K
Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
Kondo
Hidemasa
H
Noro
Natsuko
N
Suzuki
Mamoru
M
Tsuda
Sakae
S
Mitsuishi
Yasushi
Y
D000595:Amino Acid Sequence; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020080:Tandem Repeat Sequences
D043366:Cellulose 1,4-beta-Cellobiosidase