Dynamic characterisation of the netrin-like domain of human type 1 procollagen C-proteinase enhancer and comparison to the N-terminal domain of tissue inhibitor of metalloproteinases (TIMP)

Abstract

The backbone mobility of the C-terminal domain of procollagen C-proteinase enhancer (NTR^PCOLCE1), part of a connective tissue glycoprotein, was determined using ¹⁵N NMR spectroscopy. NTR^PCOLCE1 has been shown to be a netrin-like domain and adopts an OB-fold such as that found in the N-terminal domain of tissue inhibitors of metalloproteinases-1 (N-TIMP-1), N-TIMP-2, the laminin-binding domain of agrin and the C-terminal domain of complement protein C5. NMR relaxation dynamics of NTR^PCOLCE1 highlight conformational flexibility in the N-terminus, strand A and the proximal CD loop. This region in N-TIMP is known to be essential for inhibitory activity against the matrix metalloproteinases and suggests that this region is of equal importance for NTR^PCOLCE1, although the specific functional activity of the NTR^PCOLCE1 domain is still unknown. Dynamics observed within the structural core of NTR^PCOLCE1 that are not observed in N-TIMP molecules suggest that although the two domains have a similar architecture, the NTR^PCOLCE1 domain will show different thermodynamic properties on binding and hence the target molecule could be somewhat different from that observed for the TIMPs. ModelFree order parameters show that NTR^PCOLCE1 has more flexibility than both N-TIMP-1 and N-TIMP-2.