Comparative biochemical analysis of three members of the Schistosoma mansoni TAL family: Differences in ion and drug binding properties.
Bottom Line: The tegumental allergen-like (TAL) proteins from Schistosoma mansoni are part of a family of calcium binding proteins found only in parasitic flatworms.Despite the presence of two EF-hand-like structures in SmTAL3, neither was predicted to be functional.Overall, these data suggest that the proteins have different biochemical properties and thus, most likely, different in vivo functions.
Affiliation: School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK; Institute for Global Food Security, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, UK.Show MeSH
Mentions: EF-hand containing proteins (e.g calmodulin, S100 family proteins) and dynein light chains can form homodimers [56,58–61]. Previously, it has been shown that FhCaBP3 forms homodimers, although the extent of dimerization is reduced in the presence of calcium ions . In contrast, FhCaBP4 has a greater tendency to form dimers in the presence of calcium ions . All three SmTAL proteins form dimers in solution as judged by protein–protein crosslinking and SmTAL3 forms higher order oligomers (Fig. 4). Calcium ions did not affect the extent of dimerization by any of the SmTAL proteins (Fig. 4). Control experiments with human galactokinase, which is known to be monomeric from analytical gel filtration experiments , showed no crosslinking under the same conditions (Fig. 4). This suggests that, in contrast to FhCaBP3 and FhCaBP4, calcium controlled dimerization does not form part of the mechanism of action of the SmTAL proteins and that all three proteins are likely to function as dimers in vivo.
Affiliation: School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK; Institute for Global Food Security, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, UK.