4boe
Japanin from Rhipicephalus appendiculatus bound to cholesterol: Tetragonal crystal form
Structural highlights
FunctionJAP_RHIAP Salivary tick protein that modulates host immune response. This protein blocks dendritic cell (DC) differentiation from monocytes (PubMed:23825947). In addition, it inhibits up-regulation of costimulatory molecules and pro-inflammatory cytokines in response to stimuli and promotes up-regulation of co-inhibitory molecules and the anti-inflammatory cytokine interleukin-10 (PubMed:23825947). It has a pocket to accomodate cholesterol, which may have immune-modulatory roles, either directly or through interactions with the host gut microbiota (Probable).[1] [2] Publication Abstract from PubMedTwo crystal structures of Japanin, an 18 kDa immune-modulatory lipocalin from the Brown Ear Tick (Rhipicephalus appendiculatus), have been determined at 2.2 and 2.4 A resolution. In both crystal forms the protein is in complex with cholesterol, which sits in a closed pocket at the centre of the lipocalin barrel. Both crystal forms are dimers, which are also observed in solution. Molecular modelling suggests that previously-described members of a tick protein family bearing high sequence homology to Japanin are also likely to bind cholesterol or cholesterol derivatives. Structural basis of cholesterol binding by a novel clade of dendritic cell modulators from ticks.,Roversi P, Johnson S, Preston SG, Nunn MA, Paesen GC, Austyn JM, Nuttall PA, Lea SM Sci Rep. 2017 Nov 22;7(1):16057. doi: 10.1038/s41598-017-16413-2. PMID:29167574[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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