FUNCTIONAL CONFORMATIONAL-CHANGES OF ENDO-1,4-XYLANASE-II FROM TRICHODERMA-REESEI - A MOLECULAR-DYNAMICS STUDY

Recent crystallographic studies have revealed a range of structural ch anges in the three-dimensional structure of endo-1,4-xylanase (XYNII) from Trichoderma reesei. The observed conformational changes can be de scribed as snapshots of an open-close movement of the active site of X YNII. These structures were further analyzed in this study. In additio n, a total of four 1 ns molecular dynamics (MD) simulations were perfo rmed representing different states of the enzyme, A comparison of the global and local changes found in the X-ray structures and the MD runs suggested that the simulations reproduced a similar kind of active si te opening and closing as predicted by the crystal structures. The ope n-close movement was characterized by the use of distance difference m atrixes and the Hinge-find program (Wriggers and Schulten, Proteins 29 :1-14, 1997) to be a 'hinge-bending' motion involving,two large rigidl y-moving regions and an extended hinge. This conformational feature is probably inherent to this molecular architecture and probably plays a role in the function of XYNII. (C) 1998 Wiley-Liss, Inc.