Probing the effect of a plus 1bp frameshift mutation in protein-DNA interface of domestication gene, NAMB1, in wheat

Transcription factor NAM-B1 has a major role in the process of senescence, which results in higher Fe and Zn concentrations in grains of wild wheat (T. durum; Td). The absence of the wild type NAMB1 in T. aestivum (Ta), one of the cardinal crops essential for more than 1/3^rd of the global population, affects Fe and Zn remobilisation to the maturing grain from the flag leaf resulting in lesser micronutrient bioavailability. The cardinal difference in the NAMB1 gene between the two species is the absence of +1 bp allele in Ta. Insilico studies using NAMB1 from Td and Ta was performed to explore the variation in the interaction with the conserved cis-element DNA motif (CATGTG) as both the proteins share the same domain, but there are no in silico studies reported of these proteins. The secondary structure, 3D-modelling of the proteins, DNA-protein docking and dynamics have computed by Schrodinger Prime Suite. Predicted secondary structures were energy minimised using Macromodel and docking was performed based on binding energy and hydrogen bonds. Molecular dynamics simulation of NAMB1-Ta and NAMB1-Td individually and with the cis-element motif, performed for 100 ns, revealed significant variations in the protein-DNA interaction in Ta. This work provides the modelled 3D-interaction profile caused by a single bp frameshift mutation in understanding the difference in function between NAMB1 orthologs due to lack of NAC domain. The overall computational analysis reveals that NAMB1-Ta and NAMB1-Td proteins display a good amount of dissimilarity in their structure, dynamics and DNA-binding characteristics.Communicated by Ramaswamy H. Sarma.