Molecular basis for the evolved instability of a human G-protein coupled receptor

Laura M. Chamness; Nathan B. Zelt; Haley R. Harrington; Charles P. Kuntz; Brian J. Bender; Wesley D. Penn; Joshua J. Ziarek; Jens Meiler; Jonathan P. Schlebach

doi:10.1016/j.celrep.2021.110046

Molecular basis for the evolved instability of a human G-protein coupled receptor

Laura M. Chamness, Nathan B. Zelt, Haley R. Harrington, Charles P. Kuntz, Brian J. Bender, Wesley D. Penn, Joshua J. Ziarek, Jens Meiler, Jonathan P. Schlebach^*

^*Corresponding author for this work

Pharmacology

Research output: Contribution to journal › Article › peer-review

5 Scopus citations

Abstract

Membrane proteins are prone to misfolding and degradation. This is particularly true for mammalian forms of the gonadotropin-releasing hormone receptor (GnRHR). Although they function at the plasma membrane, mammalian GnRHRs accumulate within the secretory pathway. Their apparent instability is believed to have evolved through selection for attenuated GnRHR activity. Nevertheless, the molecular basis of this adaptation remains unclear. We show that adaptation coincides with a C-terminal truncation that compromises the translocon-mediated membrane integration of its seventh transmembrane domain (TM7). We also identify a series of polar residues in mammalian GnRHRs that compromise the membrane integration of TM2 and TM6. Reverting a lipid-exposed polar residue in TM6 to an ancestral hydrophobic residue restores expression with no impact on function. Evolutionary trends suggest variations in the polarity of this residue track with reproductive phenotypes. Our findings suggest that the marginal energetics of cotranslational folding can be exploited to tune membrane protein fitness.

Original language	English (US)
Article number	110046
Journal	Cell reports
Volume	37
Issue number	8
DOIs	https://doi.org/10.1016/j.celrep.2021.110046
State	Published - Nov 23 2021

Funding

We thank Christiane Hassel and the Indiana University Bloomington Flow Cytometry Core Facility for their experimental support. We thank Dr. Cheryl Heitzman for help locating and interpreting reproductive data. This research was supported in part by the National Institute of General Medical Sciences (NIGMS) (R01GM129261, R01GM080403, R01HL122010, and R01DA046138). This work was also supported by a National Science Foundation (NSF) Graduate Research Fellowship (1342962 to L.M.C.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or NIH. Conceptualization, J.P.S. and L.M.C.; Methodology, L.M.C. C.P.K. B.J.B. J.J.Z. J.M. and J.P.S.; Software, C.P.K. B.J.B. and J. M.; Formal Analysis, L.M.C. and J.P.S.; Investigation, L.M.C. N.B.Z. C.P.K. and B.J.B.; Resources, B.J.B. W.D.P. H.R.H. J.M. and J.P.S.; Writing ? Original Draft, L.M.C. and J.P.S.; Writing ? Review & Editing, L.M.C. and J.P.S.; Visualization, L.M.C. C.P.K. and J.P.S.; Supervision, J.J.Z. J.M. and J.P.S.; Funding acquisition, L.M.C. and J.P.S. The authors declare no competing interests. We thank Christiane Hassel and the Indiana University Bloomington Flow Cytometry Core Facility for their experimental support. We thank Dr. Cheryl Heitzman for help locating and interpreting reproductive data. This research was supported in part by the National Institute of General Medical Sciences (NIGMS) ( R01GM129261 , R01GM080403 , R01HL122010 , and R01DA046138 ). This work was also supported by a National Science Foundation (NSF) Graduate Research Fellowship ( 1342962 to L.M.C.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or NIH.

Keywords

GPCR
GnRHR
cotranlational folding
epistasis
membrane protein folding
protein misfolding
proteostasis
topology
translocon

ASJC Scopus subject areas

General Biochemistry, Genetics and Molecular Biology

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10.1016/j.celrep.2021.110046

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title = "Molecular basis for the evolved instability of a human G-protein coupled receptor",

abstract = "Membrane proteins are prone to misfolding and degradation. This is particularly true for mammalian forms of the gonadotropin-releasing hormone receptor (GnRHR). Although they function at the plasma membrane, mammalian GnRHRs accumulate within the secretory pathway. Their apparent instability is believed to have evolved through selection for attenuated GnRHR activity. Nevertheless, the molecular basis of this adaptation remains unclear. We show that adaptation coincides with a C-terminal truncation that compromises the translocon-mediated membrane integration of its seventh transmembrane domain (TM7). We also identify a series of polar residues in mammalian GnRHRs that compromise the membrane integration of TM2 and TM6. Reverting a lipid-exposed polar residue in TM6 to an ancestral hydrophobic residue restores expression with no impact on function. Evolutionary trends suggest variations in the polarity of this residue track with reproductive phenotypes. Our findings suggest that the marginal energetics of cotranslational folding can be exploited to tune membrane protein fitness.",

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AU - Harrington, Haley R.

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AU - Bender, Brian J.

AU - Penn, Wesley D.

AU - Ziarek, Joshua J.

AU - Meiler, Jens

AU - Schlebach, Jonathan P.

PY - 2021/11/23

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N2 - Membrane proteins are prone to misfolding and degradation. This is particularly true for mammalian forms of the gonadotropin-releasing hormone receptor (GnRHR). Although they function at the plasma membrane, mammalian GnRHRs accumulate within the secretory pathway. Their apparent instability is believed to have evolved through selection for attenuated GnRHR activity. Nevertheless, the molecular basis of this adaptation remains unclear. We show that adaptation coincides with a C-terminal truncation that compromises the translocon-mediated membrane integration of its seventh transmembrane domain (TM7). We also identify a series of polar residues in mammalian GnRHRs that compromise the membrane integration of TM2 and TM6. Reverting a lipid-exposed polar residue in TM6 to an ancestral hydrophobic residue restores expression with no impact on function. Evolutionary trends suggest variations in the polarity of this residue track with reproductive phenotypes. Our findings suggest that the marginal energetics of cotranslational folding can be exploited to tune membrane protein fitness.

AB - Membrane proteins are prone to misfolding and degradation. This is particularly true for mammalian forms of the gonadotropin-releasing hormone receptor (GnRHR). Although they function at the plasma membrane, mammalian GnRHRs accumulate within the secretory pathway. Their apparent instability is believed to have evolved through selection for attenuated GnRHR activity. Nevertheless, the molecular basis of this adaptation remains unclear. We show that adaptation coincides with a C-terminal truncation that compromises the translocon-mediated membrane integration of its seventh transmembrane domain (TM7). We also identify a series of polar residues in mammalian GnRHRs that compromise the membrane integration of TM2 and TM6. Reverting a lipid-exposed polar residue in TM6 to an ancestral hydrophobic residue restores expression with no impact on function. Evolutionary trends suggest variations in the polarity of this residue track with reproductive phenotypes. Our findings suggest that the marginal energetics of cotranslational folding can be exploited to tune membrane protein fitness.

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Molecular basis for the evolved instability of a human G-protein coupled receptor

Abstract

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Keywords

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