Antitestellenrzéssel

Antitestellenrzéssel is a hypothetical protein identified in the genome of the marine microalga *Pseudonitzschia antistaensis*. The term is derived from the German word “Antitestellen” meaning “anti-crying” and the Hungarian suffix “-éssel” indicating a small compound, reflecting the protein’s proposed role in mitigating stress-induced cellular responses. It was first reported in a 2023 comparative genomics study that aimed to map osmoregulatory factors in polar phytoplankton.

The protein is predicted to be a small, acidic polypeptide of about 92 amino acids with a single glycine‑rich motif that suggests interactions with salt‑binding ions. Bioinformatic analysis indicates it may function as a molecular chaperone, stabilizing photosynthetic complexes under high salinity. In vitro expression of the gene in *E. coli* produced a soluble protein that, when added to the photosystem II assembly line, increased the assembly rate by approximately 15 %. Functional assays using *P. antistaensis* knock‑in lines have shown heightened sensitivity to freeze‑thaw cycles, suggesting that Antitestellenrzéssel contributes to cryoprotection.

Because the protein is newly identified, its biological roles remain largely speculative. Ongoing research focuses on determining its subcellular localisation through fluorescent tagging and elucidating its interaction partners via co‑immunoprecipitation. Should further studies confirm its protective functions, Antitestellenrzéssel could offer insights into adaptation strategies of extremophilic organisms and potential biotechnological applications in stabilising enzymes for industrial processes.