Crystallization and preliminary X-ray crystallographic analysis of the β-N-acetylglucosaminidase CbsA from Thermotoga neapolitana.

The β-N-acetylglucosaminidase CbsA was cloned from the thermophilic Gram-negative bacterium Thermotoga neapolitana. Although CbsA contains a family 3 glycoside hydrolase-type (GH3-type) catalytic domain, it can be distinguished from other GH3-type β-N-acetylglucosaminidases by its high activity towards chitobiose. The homodimeric CbsA contains a unique domain at the C-terminus for which the three-dimensional structure is not yet known. In this study, CbsA was overexpressed and the recombinant protein was purified using Ni–NTA affinity and gel-filtration chromatography. The purified CbsA protein was crystallized using the vapour-diffusion method. A diffraction data set was collected to a resolution of 2.0 A at 100 K. The crystal belonged to space group R32. To obtain initial phases, the crystallization of selenomethionyl-substituted protein and the production of heavy-atom derivative crystals are in progress.