A study of Pb²⁺ induced unfolding and aggregation of arginine kinase from Euphausia superba: kinetics and computational simulation integrating study

Abstract

Arginine kinase is a crucial phosphagen kinase in invertebrates, which is associated to the environmental stress response, plays a key role in cellular energy metabolism. In this study, we investigated the Pb²⁺-induced inhibition and aggregation of Euphausia superba arginine kinase (ESAK) and found that significantly inactivated ESAK in a dose-dependent manner (IC50 = 0.058 ± 0.002 mM). Spectrofluorimetry results showed that Pb²⁺ induced tertiary structural changes via the internal polarity increased and the non-polarity decreased in ESAK and directly induced ESAK aggregation. The ESAK aggregation process induced by Pb²⁺ occurred with multi-phase kinetics. The addition of osmolytes did not show protective effect on Pb²⁺-induced inactivation of ESAK. The computational molecular dynamics (MD) simulation showed that three Pb²⁺ interrupt the entrance of the active site of ESAK and it could be the reason on the loss of activity of ESAK. Several important residues of ESAK were detected that were importantly contributed the conformation and catalytic function of ESAK. Our study showed that Pb²⁺-induced misfolding of ESAK and the complete loss of activity irreversibly, which cannot be recovered by osmolytes.

Communicated by Ramaswamy H. Sarma

Keywords:

• Euphausia superba
• arginine kinase
• Pb2⁺
• inhibition
• molecular dynamics simulation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Zhejiang Provincial Top Key Discipline of Biological engineering (KF2020005). Shang-Jun Yin was supported by National Natural Science Foundation of China (31402278), the Zhejiang Province welfare technology applied research project (LGN21C190013), the National Key Research and Development Program (2018YFD0900203), the funds from Basic Scientific Research Foundation of Zhejiang Provincial Universities and Ningbo Public Service Platform for High-Value Utilization of Marine Biological Resources. Jinhyuk Lee was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2020R1I1A2071859). Guo-Ying Qian was supported by the Zhejiang Provincial Top Key Discipline of Bioengineering (No. 2012006).