Functional Comparison of Human and Zebra Fish FKBP52 Confirms the Importance of the Proline-Rich Loop for Regulation of Steroid Hormone Receptor Activity

• Type of Material: Article
• Authors: Diondra C. Harris, University of Texas El Paso; Yenni A. Garcia, University of Texas El Paso; Cheryl Storer Samaniego, University of Texas El Paso; Veronica W. Rowlett, University of Texas El Paso; Nina R. Ortiz, University of Texas El Paso; Ashley N. Payan, University of Texas El Paso; Tatsuya Maehigashi, Emory University; Marc B. Cox, University of Texas El Paso
• Language: English
• Date: 2019-11-01
• Publisher: MDPI
• Publication Version: Final Published Version
• Copyright Statement: © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3390/ijms20215346
• Title of Journal or Parent Work: International Journal of Molecular Sciences
• ISSN: 1661-6596
• Volume: 20
• Issue: 21
• Grant/Funding Information: M.B.C is also funded by the Department of Defense (DOD) Prostate Cancer Research Program (PCRP) through grant number W81XWH-17-1-0435; and the Lizanell and Colbert Coldwell Foundation.; N.R.O. received support from the RISE Scholars Program at UTEP (NIGMS grant R25GM069621-11); Dr. Keelung Hong Graduate Research Fellowship; and Frank B. Cotton Trust Scholarship from UTEP.; This research was partially funded by grant 5U54MD007592 from the National Institutes on Minority Health and Health Disparities (NIMHD), a component of the National Institutes of Health (NIH).
• Keywords: Chemistry, Multidisciplinary; Physical Sciences; Hsp70; COCHAPERONE FKBP52; DOMAIN; Science & Technology; IMMUNOPHILIN FKBP52; Danio rerio; Life Sciences & Biomedicine; progesterone receptor; GLUCOCORTICOID-RECEPTOR; glucocorticoid receptor; CO-CHAPERONE; steroid hormone receptor; FKBP52; androgen receptor; proline-rich loop; BINDING; Biochemistry & Molecular Biology; Chemistry; zebra fish; cochaperone; HSP90; heat shock protein 90 (Hsp90); ASSOCIATION
• Research Categories: Health Sciences, Medicine and Surgery; Biology, Molecular; Chemistry, Biochemistry

Abstract

Previous studies demonstrated that the 52-kDa FK506-binding protein (FKBP52) proline-rich loop is functionally relevant in the regulation of steroid hormone receptor activity. While zebra fish (Danio rerio; Dr) FKBP52 contains all of the analogous domains and residues previously identified as critical for FKBP52 potentiation of receptor activity, it fails to potentiate activity. Thus, we used a cross-species comparative approach to assess the residues that are functionally critical for FKBP52 function. Random selection of gain-of-function DrFKBP52 mutants in Saccharomyces cerevisiae identified two critical residues, alanine 111 (A111) and threonine 157 (T157), for activation of receptor potentiation by DrFKBP52. In silico homology modeling suggests that alanine to valine substitution at position 111 in DrFKBP52 induces an open conformation of the proline-rich loop surface similar to that observed on human FKBP52, which may allow for sufficient surface area and increased hydrophobicity for interactions within the receptor–chaperone complex. A second mutation in the FKBP12-like domain 2 (FK2), threonine 157 to arginine (T157R), also enhanced potentiation, and the DrFKBP52-A111V/T157R double mutant potentiated receptor activity similar to human FKBP52. Collectively, these results confirm the functional importance of the FKBP52 proline-rich loop, suggest that an open conformation on the proline-rich loop surface is a predictor of activity, and highlight the importance of an additional residue within the FK2 domain.