Integrative Protein-Level Insights into Complementary DNA Repair, Pigment Shielding and Energy Metabolism in Radiation-Resistant Microbes

Microorganisms thriving in radiation-intense or otherwise stressful environments exhibit remarkable molecular resilience. Their survival depends on the interplay of mechanisms such as DNA repair, melanin-mediated shielding, and energy metabolism. Yet, cross-kingdom comparisons between bacteria and fungi remain limited. In this study, we conducted a functional annotation and comparative analysis of four representative proteins linked to radiation resistance: PprA from Deinococcus radiodurans, Laccase-1 from Cryptococcus neoformans, Laccase from Aspergillus niger, and NADH-ubiquinone oxidoreductase chain 4 from Cladosporium sphaerospermum. Using BLASTp, InterProScan, and KEGG pathway mapping, we explored their sequence homology, domain organization, and metabolic integration. PprA displayed high conservation across bacterial taxa and a specialized function in double-strand DNA break repair. Fungal laccases, identified as multicopper oxidases, were associated with melanin polymerization, providing pigment-based radiation protection. The mitochondrial NADH-ubiquinone oxidoreductase subunit in C. sphaerospermum indicated the central role of oxidative phosphorylation in maintaining metabolic balance under stress. Together, these findings reveal an integrative molecular framework in which DNA repair, pigment shielding, and metabolic resilience function synergistically to ensure survival in radiation-rich niches. This comparative insight underscores both the conserved and species-specific adaptations that define microbial radiation tolerance, offering new perspectives for applications in bioremediation, biotechnology, and astrobiology.