This work was funded by the National Science Centre, Poland (grant PRELUDIUM number 2021/41/N/NZ1/03086) (to P.T.) and by the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation) under Germany’s Excellence Strategy – EXC 2030 – 390661388 and – FOR 5504 – project number 496650118 (to T.H.). M.T.P. received support by the Cologne Graduate School of Aging Research. N.A.S., A.S., K.J., and M.N. were supported by the International Institute of Molecular and Cell Biology in Warsaw.

This work was funded by the National Science Centre, Poland (grant PRELUDIUM number 2021/41/N/NZ1/03086) (to P.T.) and by the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation) under Germany’s Excellence Strategy – EXC 2030 – 390661388 and – FOR 5504 – project number 496650118 (to T.H.). M.T.P. received support by the Cologne Graduate School of Aging Research. N.A.S., A.S., K.J., and M.N. were supported by the International Institute of Molecular and Cell Biology in Warsaw.

Fanconi anemia complementation groups – I (FANCI) protein facilitates DNA ICL (Inter-Cross-link) repair and plays a crucial role in genomic integrity. FANCI is a 1328 amino acids protein which contains armadillo (ARM) repeats and EDGE motif at the C-terminus. ARM repeats are functionally diverse and evolutionarily conserved domain that plays a pivotal role in protein–protein and protein–DNA interactions. Considering the importance of ARM repeats, we have explored comprehensive in silico and in vitro approach to examine folding pattern. Size exclusion chromatography, dynamic light scattering (DLS) and glutaraldehyde crosslinking studies suggest that FANCI ARM repeat exist as monomer as well as in oligomeric forms. Circular dichroism (CD) and fluorescence spectroscopy results demonstrate that protein has predominantly α- helices and well-folded tertiary structure. DNA binding was analysed using electrophoretic mobility shift assay by autoradiography. Temperature-dependent CD, Fluorescence spectroscopy and DLS studies concluded that protein unfolds and start forming oligomer from 30°C. The existence of stable portion within FANCI ARM repeat was examined using limited proteolysis and mass spectrometry. The normal mode analysis, molecular dynamics and principal component analysis demonstrated that helix-turn-helix (HTH) motif present in ARM repeat is highly dynamic and has anti-correlated motion. Furthermore, FANCI ARM repeat has HTH structural motif which binds to double-stranded DNA.

Fanconi anemia complementation groups – I (FANCI) protein facilitates DNA ICL (Inter-Cross-link) repair and plays a crucial role in genomic integrity. FANCI is a 1328 amino acids protein which contains armadillo (ARM) repeats and EDGE motif at the C-terminus. ARM repeats are functionally diverse and evolutionarily conserved domain that plays a pivotal role in protein–protein and protein–DNA interactions. Considering the importance of ARM repeats, we have explored comprehensive in silico and in vitro approach to examine folding pattern. Size exclusion chromatography, dynamic light scattering (DLS) and glutaraldehyde crosslinking studies suggest that FANCI ARM repeat exist as monomer as well as in oligomeric forms. Circular dichroism (CD) and fluorescence spectroscopy results demonstrate that protein has predominantly α- helices and well-folded tertiary structure. DNA binding was analysed using electrophoretic mobility shift assay by autoradiography. Temperature-dependent CD, Fluorescence spectroscopy and DLS studies concluded that protein unfolds and start forming oligomer from 30°C. The existence of stable portion within FANCI ARM repeat was examined using limited proteolysis and mass spectrometry. The normal mode analysis, molecular dynamics and principal component analysis demonstrated that helix-turn-helix (HTH) motif present in ARM repeat is highly dynamic and has anti-correlated motion. Furthermore, FANCI ARM repeat has HTH structural motif which binds to double-stranded DNA.