Print button

Abstract EANA2026-247


Role of Dps proteins in the radioresistance of desert cyanobacteria

D'Agostino, A. (1,2), and Billi, D. (1)
1. Department of Biology, University of Rome Tor Vergata, Rome, Italy 2. PhD Program in Cellular and Molecular Biology, Department of Biology, University of Rome Tor Vergata, Rome, Italy


The exploration of life in extreme environments has highlighted cyanobacteria of the genus Chroococcidiopsis as prime candidates for astrobiology studies due to their remarkable resistance to solar and cosmic radiation, as evidenced by previous experiments performed outside the ISS and through ground-based irradiation campaigns.

Notably, three isolates of Chroococcidiopsis, CCMEE 057, 064 and particularly CCMEE 029, exposed in both hydrated and dried state to different types of ionizing radiation (e.g., X-rays, Fe-ions) and UV-C radiation, showed outstanding radioresistance comparable to D. radiodurans. A key molecular feature contributing to such resilience may lie in specialized stress response proteins, particularly those involved in DNA protection and oxidative stress mitigation. Among them, Dps (DNA-binding proteins from starved cells) proteins are known to play a pivotal role in preventing DNA damage by physically shielding and scavenging reactive oxygen species through their ferroxidase activity.

The characterization of Dps proteins and the search for other proteins involved in radioresistance mechanisms in radiation-tolerant cyanobacteria may suggest new strategies to mitigate the radiation susceptibility of organisms relevant for developing biological systems to support human space exploration.

Using an integrated experimental and computational approach, our aim is to identify and characterise Dps proteins and assess their protective function when expressed in the radiation-sensitive bacterium Escherichia coli.

Through comparative genomic analyses, five genes encoding putative Dps proteins were identified in Chroococcidiopsis sp. CCMEE 029 using Dps sequences from the cyanobacterium Nostoc punctiforme as reference. Their coding sequences were cloned into engineered plasmids for heterologous expression in E. coli.

Preliminary results showed that E. coli expressing CCMEE 029 Dps proteins did not exhibit increased viability compared with controls following acute irradiation with either ≥75 J/m² UVC or 500 J/m² UVB.

Ongoing RT-qPCR are assessing the expression of the five Dps during the life cycle of Chroococcidiopsis sp. CCMEE 029 and in response to DNA-damaging agents.

Future work will focus on the construction of new shuttle plasmids carrying CCMEE 029 dps genes for heterologous expression in Synechocystis sp. PCC 6803, in order to evaluate their contribution to radioresistance in this radiation-sensitive cyanobacterium.