Song Z, Yuan W, Bai Z, Wang M, Huang R. Conformational study of intermediate in the unfolding of PcoC.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021;
244:118805. [PMID:
32860995 DOI:
10.1016/j.saa.2020.118805]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/29/2020] [Accepted: 08/01/2020] [Indexed: 06/11/2023]
Abstract
PcoC is a small soluble protein and is considered as a kind of copper carrier in the periplasm. The PcoC protein from E. coli possesses a β-barrel fold with two metal-binding sites of Cu2+ and Cu+. In this work, different spectroscopic techniques were adopted to clarify the stability of PcoC and metals' binding property. As demonstrated in results, Ag+ and Cu2+ are capable of binding with PcoC in a proportion of 1:1. The constant for PcoC and Cu2+ was (7.27 ± 0.21) × 1013 L/mol. In addition, we have explored how the cofactors affect the PcoC stability, finding that Cu2+ coordination affects both protein stability and unfolding pathway. The intermediate appeared during PcoC-Cu2+ unfolding. Further, the intermediate could be formed as CTAB interacted with PcoC. As found, the intermediate's C-terminal structure was unfolded, whereas the N-terminal was almost unaffected. Furthermore, the capability of the different unfolding degree protein with Cu2+ also indicated that the N-terminal exhibited a strong stability. Based on the anisotropy decay, tryptophan moved at a higher concentration of urea, also showing that the N-terminal was highly stable. In addition, the steered molecular dynamics simulations were performed, showing the rigidness of the N-terminal.
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