The hemoglobins of the trematodes Fasciola hepatica and Paramphistomum epiclitum: a molecular biological, physico-chemical, kinetic, and vaccination study.
The trematode Fasciola hepatica (Fa.he.) is a common parasite of human and livestock. The hemoglobin (Hb) of Fa.he., a potential immunogen, was chosen for characterization in the search for an effective vaccine. Characterization of trematode Hbs show that they are intracellular single-domain globins with the following remarkable features: (1) Fa.he. expresses two Hb isoforms that differ at two amino acid sites (F1: 119Y/123Q; F2: 119F/123L). Both isoforms are monoacetylated at their N-termini; (2) the genes coding for Fa.he. and Paramphistomum epiclitum (Pa.ep.) Hbs are interrupted by two introns at the conserved positions B12.2 and G7.0.; (3) UV/VIS and resonance Raman spectroscopy identify the recombinant Fa.he. HbF2 as a pentacoordinated high-spin ferrous Hb; (4) electron paramagnetic resonance spectroscopy of cyano-met Fa.he. HbF2 proves that the endogenously bound imidazole has no imidazolate character; (5) the major structural determinants of the globin fold are present, they contain a TyrB10/TyrE7 residue pair on the distal side. Although such distal-site pair is a signature for high oxygen affinity, as shown for Pa.ep. Hb, the oxygen-binding rate parameters for Fa.he. Hb are intermediate between those of myoglobin and those of other trematode Hbs; (6) the three-dimensional structure of recombinant Fa.he. HbF2 from this study closely resembles the three-dimensional structure of Pa.ep. determined earlier. The set of distal-site polar interactions observed in Pa.ep. Hb is matched with small but significant structural adjustments; (7) despite the potential immunogenic character of the fluke Hb, vaccination of calves with recombinant Fa.he. HbF2 failed to promote protection against parasitic infection.
Dewilde
Sylvia
S
Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium. sylvia.dewilde@ua.ac.be
Ioanitescu
A Iulia
AI
Kiger
Laurent
L
Gilany
Kambiz
K
Marden
Michael C
MC
Van Doorslaer
Sabine
S
Vercruysse
Jozef
J
Pesce
Alessandra
A
Nardini
Marco
M
Bolognesi
Martino
M
Moens
Luc
L
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D018360:Crystallography, X-Ray; D005210:Fasciola hepatica / Q000276:immunology*; D015801:Helminth Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000276:immunology*; D006454:Hemoglobins / Q000096:biosynthesis / Q000737:chemistry* / Q000276:immunology*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010250:Paramphistomatidae / Q000276:immunology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology; D016415:Sequence Alignment; D014611:Vaccination; D014612:Vaccines / Q000276:immunology*
D015801:Helminth Proteins; D006454:Hemoglobins; D011994:Recombinant Proteins; D014612:Vaccines