PB0164 - Identifying the differences in the structural etiology underlying coagulation Factor XIII mutations based on a 2.68 Å cryo-EM structure of the coagulation Factor XIII-A2B2 complex.

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

SS

Sneha Singh, PhD

Post Doctoral Scientist
Institute for Experimental Hematology and Transfusion Medicine, University Hospital of Bonn
Bonn, Nordrhein-Westfalen, Germany

Co-Author(s)

DU

Deniz Ugurlar

Sr. Sales Rep
Thermo Fisher Scientific
Utrecht, Utrecht, Netherlands
GH

Gregor Hagelüken

Senior Scientist, Group Leader
Institute of Structural Biology, University of Bonn
Bonn, Nordrhein-Westfalen, Germany
Samhitha Urs Ramaraje Urs, M.Sc

PhD Student
Institute for Experimental Hematology and Transfusion Medicine, University Hospital Bonn
Bonn, Nordrhein-Westfalen, Germany
Amit Sharma, MSc PhD

Research Associate
Department of Hematology, All India Institute for Medical Sciences
GHAZIABAD, Uttar Pradesh, India
MM

Manoranjan Mahapatra

Professor and Head
All India institute of Medical Sciences, New Delhi
New Delhi, Delhi, India
DI

Diana Imhof

Professor
University of Bonn
Bonn, Nordrhein-Westfalen, Germany
MG

Matthias Geyer

Professor and Director
Institute for Structural Biology, University of Bonn
Bonn, Nordrhein-Westfalen, Germany
Johannes Oldenburg, MD

Professor, Chairman and Director
University Clinic Bonn AöR, Institute of Experimental Haematology and Transfusion Medicine
Bonn, Nordrhein-Westfalen, Germany
AB

Arijit Biswas

Staff Scientist and Group leader
Institute for Experimental Hematology and Transfusion Medicine, University Hospital of Bonn
Bonn, Nordrhein-Westfalen, Germany

Background: This study delves into deciphering the cryo-electron microscopy (cryo-EM) structure of native human coagulation Factor XIII (FXIII), aiming to enhance variant interpretation and disease characterization. FXIII, a crucial player in coagulation, forms a non-covalent tetramer complex composed of dimeric-catalytic FXIII-A2 subunits and dimeric-protective FXIII-B2 subunits. Despite genetic variations in F13A1 and F13B contributing to mild and severe bleeding phenotypes, the structural intricacies of this large complex remain elusive.

Aims: The primary goal is to obtain the biophysical structure of the FXIII complex to shed light on the disease implications of genetic variants.

Methods: Native plasma FXIII, isolated from Fibrogammin P, underwent cryo-EM analysis. Simultaneously, a patient cohort with severe FXIII deficiency underwent next-generation sequencing for genetic profiling.

Results: Cryo-EM data analysis yielded a refined 2.68 Å resolution structure, revealing direct interactions between FXIII subunits, particularly through FXIII-B sushi domains 2, and FXIII-B dimerization onto FXIII-A2 dimers via sushi domain 5 (Figure 1). Heterozygous missense variants were strategically positioned closer to the complex interface than homozygous defects, suggesting a dominant-negative effect in heterozygous states. In a cohort of 17 patients, eight missense variants, including novel ones (I235F and R409L), were identified, located near the calcium-binding site and catalytic center.

Conclusion(s): In summary, this study unveils critical insights into the structural dynamics of the FXIII complex, elucidating the impact of genetic variants on its function and associated diseases. The findings contribute to a comprehensive understanding of the complex assembly in plasma and provide valuable information for interpreting FXIII variants in clinical contexts.