The role of trypsin in the absorption and utilization of Phaeodactylum tricornutum on N and P nutrients
Xueqiong Sun 1, Yanchun You 1, Jiamin He 1, Ling Li 1, Senjie Lin 1,2, *
1. College of Ocean and Earth Sciences, Xiamen University, China
2. State Key Laboratory of Marine Environmental Science (Xiamen University)
Trypsin is well known as a digestive enzyme in vertebrate animals, but its function is unknown in phytoplankton. Here we demonstrate trypsin’s critical function in regulating nitrogen(N) and phosphorus(P) nutritional balance. We find that trypsin genes are prevalent and sensitive to environmental changes. By CRISPR-Cas9 mediated-knockout and overexpression analyses coupled with physiological measurements, we document that a trypsin in the diatom Phaeodactylum tricornutum (PtTryp2) functions to repress N acquisition, but its expression decreases under N-deficiency to promotes N acquisition. On the contrary, our data indicate that PtTryp2 promote Pi uptake, and its expression increases under P-deficiency to further reinforce P acquisition. All data demonstrate that PtTryp2 is a coordinate master regulator of N-P stoichiometric homeostasis. Furthermore, we find another trypsin gene in the diatom Phaeodactylum tricornutum (PtTryp8) which also have regulating effect on nitrogen and phosphorus absorption. The function of the trypsin family needs further verification.
Keywords：Trypsin, Diatoms, nitrogen, phosphorus
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