Comparative analysis of DNA binding and abiotic stress tolerance of Dps All4145 and its homologs in Anabaena PCC 7120.

BACKGROUND

DNA-binding proteins under starvation (Dps) are mini-ferritins that sequester iron at the ferroxidase center (FOC) of a hollow protein cage. This study characterizes the novel Dps-All4145. Discrepancies between computational predictions and experimental stress responses were addressed using an integrated computational and experimental approach. Additionally, site-directed mutagenesis was performed to explore the mechanistic link between DNA binding and ferroxidation.

METHODS AND RESULTS

This study involves the molecular characterization of the novel Dps-All4145 and a comparative biochemical and structural analysis of four Dps homologs (Alr3808, All0458, All1173, and All4145) from Anabaena sp. PCC 7120. In-silico and wet lab approaches were employed to assess their biochemical functions, including iron oxidation and DNA protection. The study confirmed that iron oxidation and DNA protection are common attributes of all four Dps homologs. Additionally, all homologs contributed to abiotic stress management. Among them, Alr3808 exhibited the highest efficiency in iron oxidation and DNA protection. Site-directed mutagenesis of Alr3808K49R led to the loss of DNA-binding ability and a 60% reduction in iron oxidation, indicating the crucial role of the N-terminal lysine (K49) residue in these activities.

CONCLUSION

This study provides first-hand insights into the molecular functions of Dps proteins in Anabaena sp. PCC 7120 and highlights the unique significance of K49 in Alr3808 for iron oxidation and DNA binding.