Aspartic acid racemization and repair in the survival and recovery of hyperthermophiles after prolonged starvation at high temperature

ABSTRACT Long-term survivability is well-known for microorganisms in nutrient-depleted environments, but the damage accrued by proteins and associated repair processes during starvation recovery phase of microbial life still remain enigmatic. We focused on aspartic acid (Asp) racemization survival Pyrococcus furiosus Thermococcus litoralis under conditions at high temperature. Despite dramatic decrease viability over time, 0.002% P. cells (2.1×103 cells/mL) 0.23% T. (2.3×105 remained viable after 25 50 days, respectively. The D/L Asp ratio starved was approximately half those from autoclaved cells, suggesting that starving were capable partially repairing racemized Asp. Transcriptomic analyses recovered indicated gene encoding Protein-L-isoaspartate (D-aspartate) O-methyltransferase (PIMT) might be involved damaged converting D-Asp back to L-Asp resuscitation cells. Collectively, our results provided evidence underwent surviving hyperthermophilic PIMT played a critical role abnormal aspartyl residues initial starved, yet viable,