Kinetics and Inhibition Studies of the L205R Mutant of cAMP-Dependent Protein Kinase Involved in Cushing’s Syndrome

Authors

Nicole M. Luzi, Virginia Commonwealth University
Charles E. Lyons, Virginia Commonwealth University
Darrell L. Peterson, Virginia Commonwealth University
Keith C. Ellis, Virginia Commonwealth UniversityFollow

Document Type

Article

Original Publication Date

2018

Journal/Book/Conference Title

FEBS Open Bio

Volume

8

Issue

2018

First Page

606

Last Page

613

DOI of Original Publication

10.1002/2211-5463.12396

Comments

Originally published at https://doi.org/10.1002/2211-5463.12396

Funded in part by the VCU Libraries Open Access Publishing Fund.

Date of Submission

October 2019

Abstract

Overproduction of cortisol by the hypothalamus–pituitary–adrenal hormone system results in the clinical disorder known as Cushing's syndrome. Genomics studies have identified a key mutation (L205R) in the α‐isoform of the catalytic subunit of cAMP‐dependent protein kinase (PKACα) in adrenal adenomas of patients with adrenocorticotropic hormone‐independent Cushing's syndrome. Here, we conducted kinetics and inhibition studies on the L205R‐PKACα mutant. We have found that the L205R mutation affects the kinetics of both Kemptide and ATP as substrates, decreasing the catalytic efficiency (k_cat/K_M) for each substrate by 12‐fold and 4.5‐fold, respectively. We have also determined the IC₅₀ and K_i for the peptide substrate‐competitive inhibitor PKI(5–24) and the ATP‐competitive inhibitor H89. The L205R mutation had no effect on the potency of H89, but causes a > 250‐fold loss in potency for PKI(5–24). Collectively, these data provide insights for the development of L205R‐PKACα inhibitors as potential therapeutics.

Rights

© 2018 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Is Part Of

VCU Medicinal Chemistry Publications