Paper Citing NAMD - Abstract
Kezuka, Y.; Ohishi, M.; Itoh, Y.; Watanabe, J.; Mitsutomi, M.; Watarabe, T.; Nonaka, T.
Structural studies of a two-domain chitinase from Streptomyces griseus HUT6037
JOURNAL OF MOLECULAR BIOLOGY, 358:472-484, APR 28 2006
Chitinase C (ChiC) from Streptomyces griseus HUT6037 was the first glycoside hydrolase family 19 chitinase that was found in an organism other than higher plants. An N-terminal chitin-binding domain and a C-terminal catalytic domain connected by a linker peptide constitute ChiC. We determined the crystal structure of full-length ChiC, which is the only representative of the two-domain chitinases in the family. The catalytic domain has an alpha-helix-rich fold with a deep cleft containing a catalytic site, and lacks three loops on the domain surface compared with the catalytic domain of plant chitinases. The chitin-binding domain is an all-beta protein with two tryptophan residues (Trp59 and Trp60) aligned on the surface. We suggest the binding mechanism of tri-N-acetylchitotriose onto the chitin-binding domain on the basis of molecular dynamics (MID) simulations. In this mechanism, the ligand molecule binds well on the surface-exposed binding site through two stacking interactions and two hydrogen bonds and only Trp59 and Trp60 are involved in the binding. Furthermore, the flexibility of the Trp60 side-chain, which may be involved in adjusting the binding surface to fit the surface of crystalline chitin by the rotation of chi 2 angle, is shown. (c) 2006 Elsevier Ltd. All rights reserved.
