The P303T mutation in the human factor VII (FVII) gene alters the conformational state of the enzyme and causes a severe functional deficiency
Articolo
Data di Pubblicazione:
2004
Citazione:
The P303T mutation in the human factor VII (FVII) gene alters the conformational state of the enzyme and causes a severe functional deficiency / F. Peyvandi, R. De Cristofaro, I. Garagiola, R. Palla, S. Akhavan, R. Landolfi, P.M. Mannucci. - In: BRITISH JOURNAL OF HAEMATOLOGY. - ISSN 0007-1048. - 127:5(2004 Dec), pp. 576-584. [10.1111/j.1365-2141.2004.05241.x]
Abstract:
We report the results of in vitro expression and biochemical characterization
of the naturally occurring type II mutation Pro303Thr (P303T) in the factor
VII (FVII) gene. Recombinant activated mutated FVII (FVIIa303T),
compared with the activated wild-type FVII (FVIIaWT), showed reduced
amidase activity toward synthetic substrates, especially when the observed
reduced binding affinity for human soluble tissue factor (TF) (Kd from
4Æ4 nmol/l for FVIIaWT to 17Æ3 nmol/l for FVIIa303T) was overcome by a
fully saturating TF concentration. Likewise, factor X (FX) hydrolysis by
FVIIa303T showed a reduced activity in the absence (and more severely in the
presence) of TF (kcat/Km from 2Æ3 · 107/mol/l s for FVIIaWT to 8Æ7 · 105/
mol/l s for FVIIa303T). These results showed that the mutant FVIIa is more
shifted toward a zymogen-like form compared to FVIIaWT, suggesting that
P303 facilitates the conformational transitions that stabilize the active form of
FVIIa. The alteration of these allosteric equilibria is especially evident in the
presence of TF, which was unable to shift the equilibrium toward a fully
active FVIIa form. Additional experiments showed that both TF-catalysed
FVII303T autoactivation and FVII303T activation by activated FX in the
presence of TF were severely impaired, mainly because of an increase of the
Km value. Altogether, these defects may explain the severe bleeding symptoms
in a patient carrying the FVIIP303T mutation
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Factor VII natural mutant; FVII intrinsic activity; TF allosteric effect
Elenco autori:
F. Peyvandi, R. De Cristofaro, I. Garagiola, R. Palla, S. Akhavan, R. Landolfi, P.M. Mannucci
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