FH8--a small EF-hand protein from Fasciola hepatica

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Fraga H (Author) Other; Faria TQ (Author) Other; Pinto F (Author) Other; Almeida A (Author) Other; Brito RM (Author) Other; Damas AM (Author) Other

Journal

Title: FEBS Journal

Vol. 277 No. 24

Pages: 5072-5085

ISSN: 1742-464X

Publisher: Wiley-Blackwell

Indexing

ISI Web of Science

Pubmed / Medline

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Abstract (EN): Vaccine and drug development for fasciolasis rely on a thorough understanding of the mechanisms involved in parasite-host interactions. FH8 is an 8 kDa protein secreted by the parasite Fasciola hepatica in the early stages of infection. Sequence analysis revealed that FH8 has two EF-hand Ca(2+)-binding motifs, and our experimental data show that the protein binds Ca(2+) and that this induces conformational alterations, thus causing it to behave like a sensor protein. Moreover, FH8 displays low affinity for Ca(2+) (K(obs) = 10(4) m(-1)) and is highly stable in its apo and Ca(2+)-loaded states. Homology models were built for FH8 in both states. It has only one globular domain, with two binding sites and appropriate groups in the positions for coordination of the metal ions. However, an unusually high content of positively charged amino acids in one of the binding sites, when compared with the prototypical sensor proteins, potentially affects the protein's affinity for Ca(2+). The only Cys present in FH8, conserved in the homologous proteins of other helminth parasites, is located on the surface, allowing the formation of dimers, detected on SDS gels. These findings reflect specificities of FH8, which are most probably related to its roles both in the parasite and in the host.

Language: English

Type (Professor's evaluation): Scientific