The extracellular matrix is a dynamic environment that constantly undergoes remodelling and degradation during vital physiological processes such as angiogenesis, wound healing, and development. Unbalanced extracellular matrix breakdown is associated with many diseases such as arthritis, cancer and fibrosis. Interstitial collagen is degraded by matrix metalloproteinases with collagenolytic activity by MMP-1, MMP-8 and MMP-13, collectively known as the collagenases. Matrix metalloproteinase 1 (MMP-1) plays a pivotal role in degradation of interstitial collagen types I, II, and III. Here, we report the crystal structure of the active form of human MMP-1 at 2.67 Å resolution. This is the first MMP-1 structure that is free of inhibitor and a water molecule essential for peptide hydrolysis is observed coordinated with the active site zinc. Comparing this structure with the human proMMP-1 shows significant structural differences, mainly in the relative orientation of the hemopexin domain, between the pro form and active form of the human enzyme.

Human angiogenin (ANG), the first member of the angiogenin family (from the pancreatic ribonuclease A superfamily) to be identified, is an angiogenic factor that induces neovascularization. It has received much attention due to its involvement in the growth of tumors and its elevated expression level in pancreatic and several other cancers. Recently the biological role of ANG has been shown to extend to the nervous system. Mutations in ANG have been linked with familial as well as sporadic forms of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder characterized by selective destruction of motor neurons. Furthermore, mouse angiogenin-1 has been shown to be expressed in the developing nervous system and during the neuronal differentiation of pluripotent stem cells. We have now characterized the seven variants of ANG reported in ALS patients with respect to the known biochemical properties of ANG and further studied the biological properties of three of these variants. Our results show that the ribonucleolytic activity of six of the seven ANG-ALS implicated variants is significantly reduced or lost and some variants also show altered thermal stability. We report a significant reduction in the cell proliferative and angiogenic activities of the three variants that we chose to investigate further. Our studies on the biochemical and structural features of these ANG variants now form the basis for further investigations to determine their role(s) in ALS.Amyotrophic lateral sclerosis (ALS) 1 is a fatal neurodegenerative disorder characterized by selective destruction of motor neurons (1). In the past decade, a small number of genes involved in the etiology of the disease have been identified (for a recent review see ref 2). The best studied of these is SOD1 (3), the gene for Cu/Zn superoxide dismutase. More than a hundred SOD1 mutations have now been linked with ALS, and motor neuron death from many of these mutations has been shown to result from a toxic gain of function rather than loss of dismutase activity. However, mutations in SOD1 account for only 1-2% of all cases of ALS and 20% of the familial cases. Some of the other proteins implicated in ALS are the vesicle-trafficking protein VAPB (4); ALSIN, a putative guanine nucleotide factor for GTPase (5); and senataxin (6). In addition, vascular endothelial growth factor (VEGF), an angiogenic factor that plays an important role in motor neuron survival, has been linked with ALS (7-10). However, the causes and molecular mechanisms underlying ALS are still largely unclear, and effective therapies do not appear to be imminent. Angiogenin (ANG), which encodes an angiogenic protein, was recently identified as a candidate susceptibility gene for ALS in the Irish and Scottish population by Greenway et al. (11). In a further study of over 2500 individuals from five independent populations from northern Europe and North America, Greenway et al. (12) found seven missense mutations (Figure 1) in 11 unrelated individuals with sporadic ALS and in f...

The angiogenic molecule placenta growth factor (PlGF) is a member of the cysteine-knot family of growth factors. In this study, a mature isoform of the human PlGF protein, PlGF-1, was crystallized as a homodimer in the crystallographic asymmetric unit, and its crystal structure was elucidated at 2.0 Å resolution. The overall structure of PlGF-1 is similar to that of vascular endothelial growth factor (VEGF) with which it shares 42% amino acid sequence identity. Based on structural and biochemical data, we have mapped several important residues on the PlGF-1 molecule that are involved in recognition of the fms-like tyrosine kinase receptor (Flt-1, also known as VEGFR-1). We propose a model for the association of PlGF-1 and Flt-1 domain 2 with precise shape complementarity, consider the relevance of this assembly for PlGF-1 signal transduction, and provide a structural basis for altered specificity of this molecule.