4zm8 | pdb_00004zm8
Crystal Structure of Sialostatin L
Structural highlights
FunctionCYTL_IXOSC Inhibitor of cysteine proteinases. Inhibits host immune responses via its inhibition of host cathepsins (PubMed:19494265). Contributes to the suppression of the host's immune response to tick salivary proteins and is important for successful feeding on hosts (PubMed:17698852). Inhibits differentiation of host dendritic cells (PubMed:19494265, PubMed:25975355). Inhibits proliferation of host T-cells in response to antigen stimulus (PubMed:19494265). Down-regulates TLR2-mediated host responses to infection by B.burgdorferi and the production of the chemokine CCL3 by host dendritic cells (PubMed:25975355). Down-regulates host responses to infection by B.burgdorferi and the production of IFNB1 by host dendritic cells (PubMed:25975355). Down-regulates IL1B production by host mast cells, and this then leads to impaired activation of IL1R1, resulting in decreased IL9 production (PubMed:26078269). Inhibits host inflammatory reactions and recruitment of host neutrophils (PubMed:16772304). Inhibits papain and cathepsin-L (CTSL) (in vitro) (PubMed:16772304, PubMed:17698852, PubMed:20545851). Inhibits cathepsin-S (CTSS) (in vitro) (PubMed:17698852, PubMed:20545851). Inhibits CTSV and CTSC, but to a lesser degree (in vitro) (PubMed:16772304, PubMed:17698852).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedWe have previously demonstrated that two salivary cysteine protease inhibitors from the Borrelia burgdorferi (Lyme disease) vector Ixodes scapularis- namely sialostatins L and L2 - play an important role in tick biology, as demonstrated by the fact that silencing of both sialostatins in tandem results in severe feeding defects. Here we show that sialostatin L2 - but not sialostatin L - facilitates the growth of B. burgdorferi in murine skin. To examine the structural basis underlying these differential effects of the two sialostatins, we have determined the crystal structures of both sialostatin L and L2. This is the first structural analysis of cystatins from an invertebrate source. Sialostatin L2 crystallizes as a monomer with an 'unusual' conformation of the N-terminus, while sialostatin L crystallizes as a domain-swapped dimer with an N-terminal conformation similar to other cystatins. Deletion of the 'unusual' N-terminal five residues of sialostatin L2 results in marked changes in its selectivity, suggesting that this region is a particularly important determinant of the biochemical activity of sialostatin L2. Collectively, our results reveal the structure of two tick salivary components that facilitate vector blood feeding and that one of them also supports pathogen transmission to the vertebrate host. The crystal structures of two salivary cystatins from the tick Ixodes scapularis and the effect of these inhibitors on the establishment of Borrelia burgdorferi infection in a murine model.,Kotsyfakis M, Horka H, Salat J, Andersen JF Mol Microbiol. 2010 Jul;77(2):456-70. Epub 2010 Jun 1. PMID:20545851[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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