3pvk
Secreted aspartic protease 2 in complex with benzamidine
Structural highlights
FunctionCARP2_CANAX Secreted aspartic peptidases (SAPs) are a group of ten acidic hydrolases considered as key virulence factors (PubMed:11478679, PubMed:12761103, PubMed:15820985, PubMed:15845479, PubMed:19880183, PubMed:20713630, PubMed:22302440, PubMed:23927842). These enzymes supply the fungus with nutrient amino acids as well as are able to degrade the selected host's proteins involved in the immune defense (PubMed:11478679, PubMed:12761103, PubMed:15820985, PubMed:15845479, PubMed:19880183, PubMed:20713630, PubMed:22302440, PubMed:23927842). Induces host inflammatory cytokine production in a proteolytic activity-independent way (PubMed:20713630). Plays a role in tissue damage during superficial infection (PubMed:12761103). Moreover, acts toward human hemoglobin though limited proteolysis to generate a variety of antimicrobial hemocidins, enabling to compete with the other microorganisms of the same physiological niche using the microbicidal peptides generated from the host protein (PubMed:23927842).[1] [2] [3] [4] [5] [6] [7] [8] Plays a key role in defense against host by cleaving histatin-5 (Hst 5), a peptide from human saliva that carries out fungicidal activity (PubMed:27390786, PubMed:29143452, PubMed:31675138). The cleavage rate decreases in an order of SAP2 > SAP9 > SAP3 > SAP7 > SAP4 > SAP1 > SAP8 (PubMed:27390786). The first cleavage occurs between residues 'Lys-17' and 'His-18' of Hst 5, giving DSHAKRHHGYKRKFHEK and HHSHRGY peptides (PubMed:27390786). Simultaneously, the DSHAKRHHGYKRK peptide is also formed (PubMed:27390786). Further fragmentation by SAP2 results in FHEK and DSHAKRHHGY products (PubMed:27390786).[9] [10] [11] Publication Abstract from PubMedSmall highly soluble probe molecules such as aniline, urea, N-methylurea, 2-bromoacetate, 1,2-propanediol, nitrous oxide, benzamidine, and phenol were soaked into crystals of various proteins to map their binding pockets and to detect hot spots of binding with respect to hydrophobic and hydrophilic properties. The selected probe molecules were first tested at the zinc protease thermolysin. They were then applied to a wider range of proteins such as protein kinase A, D-xylose isomerase, 4-diphosphocytidyl-2C-methyl-D-erythritol synthase, endothiapepsin, and secreted aspartic protease 2. The crystal structures obtained clearly show that the probe molecules populate the protein binding pockets in an ordered fashion. The thus characterized, experimentally observed hot spots of binding were subjected to computational active site mapping using HotspotsX. This approach uses knowledge-based pair potentials to detect favorable binding positions for various atom types. Good agreement between the in silico hot spot predictions and the experimentally observed positions of the polar hydrogen bond forming functional groups and hydrophobic portions was obtained. Finally, we compared the observed poses of the small-molecule probes with those of much larger structurally related ligands. They coincide remarkably well with the larger ligands, considering their spatial orientation and the experienced interaction patterns. This observation confirms the fundamental hypothesis of fragment-based lead discovery: that binding poses, even of very small molecular probes, do not significantly deviate or move once a ligand is grown further into the binding site. This underscores the fact that these probes populate given hot spots and can be regarded as relevant seeds for further design. Experimental and Computational Active Site Mapping as a Starting Point to Fragment-Based Lead Discovery.,Behnen J, Koster H, Neudert G, Craan T, Heine A, Klebe G ChemMedChem. 2011 Dec 23. doi: 10.1002/cmdc.201100490. PMID:22213702[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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