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Tandem Repeat of a Seven-Bladed beta-Propeller Domain in Oligoxyloglucan Reducing-End-Specific Cellobiohydrolase

(2004) Structure 12: 1209-1217

• PubMed: 15242597 Search on PubMed
• DOI: https://doi.org/10.1016/j.str.2004.04.020
• Primary Citation of Related Structures:  
  1SQJ


• PubMed Abstract: 
  

  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.

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Organizational Affiliation: 

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.