Hemelipoglycoprotein from the ornate sheep tick, Dermacentor marginatus: structural and functional characterization

Abstract

BackgroundTick carrier proteins are able to bind, transport, and store host-blood heme, and thus they function also as antioxidants. Nevertheless, the role of carrier proteins in ticks is not fully understood. Some of them are found also in tick males which do not feed on hosts to such an extent such as females (there are differences in male feeding in different tick species) and thus they are not dealing with such an excess of heme; some of the carrier proteins were found in salivary glands where the processing of blood and thus release of heme does not occur. Besides, the carrier proteins bind relatively low amounts of heme (in one case only two molecules of heme per protein) compared to their sizes (above 200 kDa).The main aim of this study is the biochemical characterization of a carrier protein from the ornate sheep tick Dermacentor marginatus, hemelipoglycoprotein, with emphasis on its size in native conditions, its glycosylation and identification of its modifying glycans, and examining its carbohydrate-binding specificity.ResultsHemelipoglycoprotein from D. marginatus plasma was purified in native state by immunoprecipitation and denatured using electroelution from SDS-PAGE separated plasma. The protein (290 kDa) contains two subunits with molecular weights 100 and 95 kDa. It is glycosylated by high-mannose and complex N-glycans HexNAc2Hex9, HexNAc2Hex10, HexNAc4Hex7, and HexNAc4Hex8. The purified protein is able to agglutinate red blood cells and has galactose- and mannose-binding specificity. The protein is recognized by antibodies directed against plasma proteins with hemagglutination activity and against fibrinogen-related lectin Dorin M from the tick Ornithodoros moubata.It forms high-molecular weight complexes with putative fibrinogen-related proteins and other unknown proteins under native conditions in tick plasma. Feeding does not increase its amounts in male plasma. The hemelipoglycoprotein was detected also in hemocytes, salivary glands, and gut. In salivary glands, the protein was present in both glycosylated and nonglycosylated forms.ConclusionA 290 kDa hemelipoglycoprotein from the tick Dermacentor marginatus, was characterized. The protein has two subunits with 95 and 100 kDa, and bears high-mannose and complex N-linked glycans. In hemolymph, it is present in complexes with putative fibrinogen-related proteins. This, together with its carbohydrate-binding activity, suggests its possible involvement in tick innate immunity. In fed female salivary glands, it was found also in a form corresponding to the deglycosylated protein.

Population genetic analysis of the DARC locus (Duffy) reveals adaptation from standing variation associated with malaria resistance in humans

“…The past and current arid climate have made southern Africa a poor habitat for mosquitoes, reducing the associated risk of infection [71]. Furthermore, local and global ancestry results indicate that FY*O may be due to recent gene flow into these populations, as ≠Khomani San FY*O carriers are significantly enriched for global Bantu ancestry and local Bantu ancestry in the FY*O region, relative to non-carriers.…”

Gut transcriptome analysis on females of Ornithodoros mimon (Acari: Argasidae) and phylogenetic inference of ticks

“…These organelles are formed by transport and delivery of carrier proteins such as hemelipoglycoproteins, which are associated with heme (MAYA-MONTEIRO et al, 2000;LARA et al, 2005;DUPEJOVA et al, 2011). Hemelipoglycoprotein in O. mimon constitute a transcript with high levels of RPKM, possibly indicating gene expression in response to digestion of the blood meal, in order to accumulate heme.…”

Molecular characterization of two vitellogenin genes from the tick, Amblyomma hebraeum (Acari: Ixodidae)

“…Based on sequence homology, these two genes are likely derived from a common ancestral gene (Donohue et al, 2009). CPs have been characterized in A. americanum (Madden et al, 2004), D. variabilis and O. parkeri (Gudderra et al, 2001(Gudderra et al, , 2002, with similar HeLP and HLGP proteins identified in R. microplus (Maya-Monteiro et al, 2000) and D. marginatus (Dupejova et al, 2011). Consensus sequences homologous to the D. variabilis CP have been identified in R. appendiculatus (Nene et al, 2004), A. variegatum (Nene et al, 2002) and A. cajennense (Batista et al, 2008).…”