Coagulation Factor XIIIA Subunit Missense Mutations Affect Structure and Function at the Various Steps of Factor XIII Action

Abstract

Inherited defects of coagulation Factor XIII (FXIII) can be categorized into severe and mild forms based on their genotype and phenotype. Heterozygous mutations occurring in F13A1 and F13B genes causing mild FXIII deficiency have been reported only in the last few years primarily because the mild FXIII deficiency patients are often asymptomatic unless exposed to some kind of a physical trauma. However, unlike mutations causing severe FXIII deficiency, many of these mutations have not been comprehensively characterized based on expression studies. In our current article, we have transiently expressed 16 previously reported missense mutations detected in the F13A1 gene of patients with mild FXIII deficiency and analyzed their respective expression phenotype. Complimentary to expression analysis, we have used in silico analysis to understand and explain some of the in vitro findings. The expression phenotype has been evaluated with a number of expression phenotype determining assays. We observe that the mutations influence different aspects of FXIII function and can be functionally categorized on the basis of their expression phenotype. We identified mutations which even in heterozygous form would have strong impact on the functional status of the protein (namely mutations p.Arg716Gly, p.Arg704Gln, p.Gln602Lys, p.Leu530Pro, p.His343Tyr, p.Pro290Arg, and p.Arg172Gln).

Proline 36 of the Factor XIII Activation Peptide Plays a Crucial Role in Substrate Recognition and Zymogen Activation

“…Two heterozygous mutations directly at the thrombin cleavage site, Arg37Gln and Arg37Pro, were expressed and were confirmed to lead to a FXIII-A type II deficiency with mildly decreased normal antigen levels but severely decreased FXIII activity. 34 It is not surprising, that FXIII activation is inhibited when the thrombin cleavage site itself is abolished by mutation. In our case, however, mutation of the neighbouring amino acid had a similar deleterious effect.…”

“…Structural data of the FXIII-A 2 dimer 12 and the AP-FXIII (28)(29)(30)(31)(32)(33)(34)(35)(36)(37) in complex with thrombin 13 were obtained from the Protein Data Bank (PDB-ID 1F13 and 1DE7; www.rcsb.org). Visualization of Pro36 within the molecular context and preparation of the figures was done with DeepView/Swiss-Pdb Viewer v.4.1.0 (www.expasy.org/spdbv/).…”

Structure functional insights into calcium binding during the activation of coagulation factor XIII A

“…fibrinogen, BAPA and α-2 antiplasmin were considered since the endpoint FXIII activity assays dealt with these substrates. These binding regions had been determined by rigid docking studies we had earlier conducted and reported for fibrinogen and α-2 antiplasmin 52 .The putative BAPA binding region(s) were predicted by docking the structural coordinates of BAPA [5-(Biotinamido) pentylamine; Pubchem ID: CID 83906] that were downloaded from Pubchem database (as an SDF file and later converted to a PDB file on YASARA), onto the activated FXIII-A crystal structure (PDB ID: 4kty) downloaded from the protein database. Semi-flexible docking was performed with the Autodock function embedded in YASARA 52 .Finally these binding regions were mapped and highlighted on the FXIII-A subunit activation transition state intermediate models.…”

Functional and Structural Characterization of Nucleic Acid Ligands That Bind to Activated Coagulation Factor XIII

“…The structure of FXIIIa that was used as the receptor in the docking simulations was obtained in a pre-equilibrated state from the MD trajectory of the crystal structure of FXIIIa (PDB: 4KTY) reported in an earlier study [34,35]. The highest scoring docking poses for each aptamer was critically analyzed with respect to previously suggested fibrinogen (mainly alpha chain) and α2AP binding site residues as well as catalytically important active site residues [36]. Electrostatic surface potential of the FXIIIa was calculated and graphically depicted using the Adaptive Poisson-Boltzmann Solver integrated within YASARA.…”