Deinococcus radiodurans is an extreme bacterium capable of withstanding ionizing radiation-induced oxidative stress. Non-enzymatic manganese antioxidant complexes play an important role in its resistance to oxidative stress. Here, we demonstrate that the PitA homolog (DrPitA) encoded by dr0925, a low-affinity metal-phosphate transporter homolog, mediates enrichment of intracellular manganese-phosphate (Mn-Pi) and participates in the oxidative resistance of D. radiodurans. The mutation of drpitA significantly reduced intracellular Mn ion and phosphate levels, concomitant with the compromised cell survival under oxidative stress. Under H2O2 stress, the drpitA mutant accumulated excessive reactive oxygen species, resulting in severe protein carbonylation damage compared with the wild type strain. Moreover, the drpitA mutant cells exhibit decreased intracellular polyphosphate (PolyP) under H2O2 stress, indicating that the DrPitA-mediated Mn-Pi enrichment may be related to PolyP metabolism. Our findings establish that the DrPitA contributes to oxidative stress resistance of D. radiodurans by facilitating Mn-Pi enrichment.IMPORTANCEAs a model bacterium for extreme environmental adaptation, studies on the exceptional resistance of Deinococcus radiodurans have been focused on its DNA damage repair pathways and antioxidant systems. Among the antioxidant systems, the non-enzymic Mn-antioxidant complexes, including manganese-phosphate (Mn-Pi), which has efficient intracellular reactive oxygen species scavenging and protection of biomolecules from oxidative damage, play a significant role in stress resistance. However, the mechanism underlying Mn-Pi enrichment in D. radiodurans remains obscure. Therefore, investigating Mn-Pi transporter and their role in Mn-Pi homeostasis is important for understanding the oxidative stress resistance of this bacterium. In this study, we characterized the PitA homolog (DrPitA) as a transporter involved in Mn-Pi accumulation in D. radiodurans. We demonstrated that the DrPitA contributes to oxidative stress resistance through the acquisition of Mn ion and phosphate. These findings broaden understanding of the accumulation mechanism of non-enzymatic antioxidants in D. radiodurans and provide insights into how the extreme bacterium survives under oxidative stress.
Xie et al. (Tue,) studied this question.