The activation peptide of coagulation factor XIII is vital for its expression and stability. (16th July 2015)

• Record Type: Journal Article
• Authors: Handrkova, H.; Schroeder, V.; Kohler, H. P.
• Is Part Of: Journal of thrombosis and haemostasis. Volume 13:Number 8(2015:Aug.)
• Page Start: 1449
• Page End: 1458
• Publication Date: 2015-07-16
• Subjects: Thrombosis -- Periodicals; Hemostasis -- Periodicals; Blood coagulation disorders -- Periodicals; 616.1
• DOI: 10.1111/jth.13035
• Languages: English
• ISSNs: 1538-7933

Abstract

<abstract abstract-type="main" id="jth13035-abs-0001"> <title>Summary</title> <sec id="jth13035-sec-0001" sec-type="section"> <title>Background</title> <p>The human activation peptide of factor XIII (AP‐FXIII) comprises the first 37 amino acids of the N‐terminus and holds the FXIII in an inactive state. FXIII is activated either proteolytically by cleavage of AP‐FXIII by thrombin, or non‐proteolytically by high calcium concentrations.</p> </sec> <sec id="jth13035-sec-0002" sec-type="section"> <title>Objective</title> <p>To investigate the role of AP‐FXIII in the expression and stability of FXIII.</p> </sec> <sec id="jth13035-sec-0003" sec-type="section"> <title>Methods</title> <p>We cloned 13 FXIII variants with progressive truncations of AP‐FXIII from the N‐terminus (delN‐FXIII‐A), expressed them in mammalian cells, and measured their thermostability, activation, and transglutaminase activity. We also used <italic>in silico</italic> calculations to analyze the stability of hypothetical delN‐FXIII dimers and to identify crucial motifs within AP‐FXIII.</p> </sec> <sec id="jth13035-sec-0004" sec-type="section"> <title>Results</title> <p>Variants with deletions longer than the first 10 amino acids and an R11Q point mutant were not expressed as proteins. <italic>In silico</italic> calculations indicated that the sequence <sup>8</sup>FGGR<sup>12</sup>R plays a substantial role in intersubunit interactions in FXIII‐A<sub>2</sub> homodimers. In agreement with this prediction, the temperature stability of delN‐FXIII variants decreased with increasing length of deletion. These results may suggest a role of the N‐terminus of AP‐FXIII in dimer stability. Substantial sequence homology was found among activation peptides of vertebrate and even invertebrate (crustacean) FXIII‐A orthologs, which further supports our conclusion.</p> </sec> <sec id="jth13035-sec-0005" sec-type="section"> <title>Conclusions</title> <p>We conclude that deletion of 11 or more N‐terminal amino acids disrupts intersubunit interactions, which may prevent FXIII‐A<sub>2</sub> homodimer formation. Therefore, AP‐FXIII plays an important role in the stability of the FXIII‐A<sub>2</sub> dimer.</p> </sec> </abstract>