A Protein with a Novel Calcium-Binding Domain Associated with Calcareous Corpuscles inEchinococcus granulosus

The DxDxDG Motif for Calcium Binding: Multiple Structural Contexts and Implications for Evolution

“…19 The E. granulosus Ca 2C -binding domain consists mainly of 15 copies of a 12-14 residues repeat in which a DxDxDG motif is separated by two residues from a later, invariant Asp. 50 In the present database, only another tapeworm and Drosophila seem to possess homologues with the same characteristics. In FrpC, five DxDxDG motifs can be identified, most interestingly with diverse separations of DxDxDG loops and putative additional Ca 2C ligands ( Table 2).…”

“…In the cases of FrpC, 49 a member of the RTX protein family, E. granulosus Ca 2C -binding protein 50 and caleosin, 51 Ca 2C binding has been experimentally observed. In the case of the Excalibur domain, Ca 2C binding has not yet been demonstrated, but the combinations of several Ca 2C -dependent or Ca 2C -regulated domains with Excalibur provide circumstantial support for binding.…”

Functional expression and characterization of Echinococcus granulosus thioredoxin peroxidase suggests a role in protection against oxidative damage

“…As well as being calcium and phosphate stores in protoscoleces, these bodies are made up of other inorganic and organic material containing RNA, DNA, glycogen, mucopolysaccharides, various lipids and proteins including alkaline phosphatase (Smyth and McManus, 1989). The functions of calcareous corpuscles are not well understood, but in addition to being a ready source of calcium carbonate, they have been implicated not only in protective functions including buffering of anaerobically produced acids and buffering against gastric hydrochloric acid but also roles in lipid metabolism, osmotic balance, anticomplement activity, in tissue repair, and as reservoirs of metabolites for metabolic requirements (Smyth and McManus, 1989;Rodrigues et al, 1997). Calcareous corpuscles may also act as a repository of EgTPx, so that the enzyme can be released rapidly and in sufficient quantity to help the parasite to escape oxidative damage and to play a role in other key biological processes including energy transformation and differentiation.…”

“…Calcareous corpuscles may also act as a repository of EgTPx, so that the enzyme can be released rapidly and in sufficient quantity to help the parasite to escape oxidative damage and to play a role in other key biological processes including energy transformation and differentiation. It is noteworthy that the corpuscles are lost rapidly during parasite establishment in the definitive host (Rodrigues et al, 1997) coinciding with a period of rapid development and significant physiological, including oxidative, stress for the parasite. The occurrence of EgTPx immunoreactivity in some, but not all, calcareous corpuscles, and the disposition of the molecule towards the periphery of those that do label, suggests a role also for EgTPx in the actual formation of the calcareous corpuscles.…”

Extracellular calcium triggers unique transcriptional programs and modulates staurosporine-induced cell death in Neurospora crassa

“…Molecular modeling of NCU06607 was not feasible because the Dx[DN]xDG motif is not located within a folded domain of known structure, but at the beginning of a predicted intrinsically disordered region. Anyway, the Dx[DN]xDG motif is sometimes found in highly disordered regions 36. NCU06607 has a predicted extracellular localization and there is a strong bias in the localization of proteins possessing the Dx[DN]xDG motif towards the cell surface or secretion 22.…”