Cellular ATP Levels Determine the Stability of a Nucleotide Kinase

Oliver Brylski; Puja Shrestha; Patricia Gnutt; David Gnutt; Jonathan Wolf Mueller; Simon Ebbinghaus

doi:10.3389/fmolb.2021.790304

Cellular ATP Levels Determine the Stability of a Nucleotide Kinase

Front Mol Biosci. 2021 Dec 13:8:790304. doi: 10.3389/fmolb.2021.790304. eCollection 2021.

Authors

Oliver Brylski^{1

2

3}, Puja Shrestha^{1

2}, Patricia Gnutt³, David Gnutt^{1

2

3}, Jonathan Wolf Mueller^{4

5}, Simon Ebbinghaus^{1

2

3}

Affiliations

¹ Institute of Physical and Theoretical Chemistry, TU Braunschweig, Braunschweig, Germany.
² Braunschweig Integrated Centre of Systems Biology (BRICS), Braunschweig, Germany.
³ Institute of Physical Chemistry II, Ruhr University, Bochum, Germany.
⁴ Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, United Kingdom.
⁵ Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, United Kingdom.

Abstract

The energy currency of the cell ATP, is used by kinases to drive key cellular processes. However, the connection of cellular ATP abundance and protein stability is still under investigation. Using Fast Relaxation Imaging paired with alanine scanning and ATP depletion experiments, we study the nucleotide kinase (APSK) domain of 3'-phosphoadenosine-5'-phosphosulfate (PAPS) synthase, a marginally stable protein. Here, we show that the in-cell stability of the APSK is determined by ligand binding and directly connected to cellular ATP levels. The observed protein stability change for different ligand-bound states or under ATP-depleted conditions ranges from ΔG_f ⁰ = -10.7 to +13.8 kJ/mol, which is remarkable since it exceeds changes measured previously, for example upon osmotic pressure, cellular stress or differentiation. The results have implications for protein stability during the catalytic cycle of APS kinase and suggest that the cellular ATP level functions as a global regulator of kinase activity.

Keywords: ATP depletion; PAPS synthase; alanine scanning; cellular stress; in-cell spectroscopy; ligand binding; protein folding stability; sulfation pathways.