Protein Transphosphorylation During the Mutual Interaction between Phytochrome A and a Nuclear Isoform of Nucleoside Diphosphate Kinase Is Regulated by Red Light

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A. Hetmann, M. Wujak^*, and S. Kowalczyk

Nicolaus Copernicus University, Faculty of Biology and Environment Protection, Department of Biochemistry, 1 Lwowska St, 87-100 Toruń, Poland; E-mail: mag_wuj@umk.pl

^* To whom correspondence should be addressed.

Received May 25, 2016; Revision received June 30, 2016

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The nuclear isoform of nucleoside diphosphate kinase isoenzyme NDPK-I_n undergoes strong catalytic activation upon its interaction with the active form of phytochrome A (Pfr) in red light. The autophosphorylation or intermolecular transphosphorylation of NDPK-I_n leads to the formation of phosphoester bonds stable in acidic solution. The phosphate residue of the phosphamide bond in the active center of NDPK-I_n can also be transferred to serine and threonine residues localized in other proteins, including phytochrome A. Phytochrome A, similarly to NDPK-I_n, undergoes autophosphorylation on serine and threonine residues and can phosphorylate some potential substrate proteins. The physical interaction between phytochrome A in the Pfr form and NDPK-I_n results in a significant increase in the kinase activity of NDPK-I_n. The results presented in this work indicate that NDPK-I_n may function as a protein kinase regulated by light.

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KEY WORDS: nucleoside diphosphate kinase, phytochrome, signal transduction, transphosphorylation

DOI: 10.1134/S0006297916100126

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