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Title: Contributions of the Interdomain Loop, Amino Terminus, and Subunit Interface to the Ligand-Facilitated Dimerization of Neurophysin: Crystal Structures and Mutation Studies of Bovine Neurophysin-I

Abstract

Current evidence indicates that the ligand-facilitated dimerization of neurophysin is mediated in part by dimerization-induced changes at the hormone binding site of the unliganded state that increase ligand affinity. To elucidate other contributory factors, we investigated the potential role of neurophysin's short interdomain loop (residues 55-59), particularly the effects of loop residue mutation and of deleting amino-terminal residues 1-6, which interact with the loop and adjacent residues 53-54. The neurophysin studied was bovine neurophysin-I, necessitating determination of the crystal structures of des 1-6 bovine neurophysin-I in unliganded and liganded dimeric states, as well as the structure of its liganded Q58V mutant, in which peptide was bound with unexpectedly increased affinity. Increases in dimerization constant associated with selected loop residue mutations and with deletion of residues 1-6, together with structural data, provided evidence that dimerization of unliganded neurophysin-I is constrained by hydrogen bonding of the side chains of Gln58, Ser56, and Gln55 and by amino terminus interactions, loss or alteration of these hydrogen bonds, and probable loss of amino terminus interactions, contributing to the increased dimerization of the liganded state. An additional intersubunit hydrogen bond from residue 81, present only in the liganded state, was demonstrated as the largest single effectmore » of ligand binding directly on the subunit interface. Comparison of bovine neurophysins I and II indicates broadly similar mechanisms for both, with the exception in neurophysin II of the absence of Gln55 side chain hydrogen bonds in the unliganded state and a more firmly established loss of amino terminus interactions in the liganded state. Evidence is presented that loop status modulates dimerization via long-range effects on neurophysin conformation involving neighboring Phe22 as a key intermediary.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930403
Report Number(s):
BNL-81130-2008-JA
Journal ID: ISSN 0961-8368; TRN: US200904%%683
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Protein Science; Journal Volume: 16
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 36 MATERIALS SCIENCE; AFFINITY; BONDING; CATTLE; CHAINS; CRYSTAL STRUCTURE; DIMERIZATION; HORMONES; HYDROGEN; MUTATIONS; PEPTIDES; PROTEINS; RESIDUES; national synchrotron light source

Citation Formats

Li,X., Lee, H., Wu, J., and Breslow, E. Contributions of the Interdomain Loop, Amino Terminus, and Subunit Interface to the Ligand-Facilitated Dimerization of Neurophysin: Crystal Structures and Mutation Studies of Bovine Neurophysin-I. United States: N. p., 2007. Web.
Li,X., Lee, H., Wu, J., & Breslow, E. Contributions of the Interdomain Loop, Amino Terminus, and Subunit Interface to the Ligand-Facilitated Dimerization of Neurophysin: Crystal Structures and Mutation Studies of Bovine Neurophysin-I. United States.
Li,X., Lee, H., Wu, J., and Breslow, E. Mon . "Contributions of the Interdomain Loop, Amino Terminus, and Subunit Interface to the Ligand-Facilitated Dimerization of Neurophysin: Crystal Structures and Mutation Studies of Bovine Neurophysin-I". United States. doi:.
@article{osti_930403,
title = {Contributions of the Interdomain Loop, Amino Terminus, and Subunit Interface to the Ligand-Facilitated Dimerization of Neurophysin: Crystal Structures and Mutation Studies of Bovine Neurophysin-I},
author = {Li,X. and Lee, H. and Wu, J. and Breslow, E.},
abstractNote = {Current evidence indicates that the ligand-facilitated dimerization of neurophysin is mediated in part by dimerization-induced changes at the hormone binding site of the unliganded state that increase ligand affinity. To elucidate other contributory factors, we investigated the potential role of neurophysin's short interdomain loop (residues 55-59), particularly the effects of loop residue mutation and of deleting amino-terminal residues 1-6, which interact with the loop and adjacent residues 53-54. The neurophysin studied was bovine neurophysin-I, necessitating determination of the crystal structures of des 1-6 bovine neurophysin-I in unliganded and liganded dimeric states, as well as the structure of its liganded Q58V mutant, in which peptide was bound with unexpectedly increased affinity. Increases in dimerization constant associated with selected loop residue mutations and with deletion of residues 1-6, together with structural data, provided evidence that dimerization of unliganded neurophysin-I is constrained by hydrogen bonding of the side chains of Gln58, Ser56, and Gln55 and by amino terminus interactions, loss or alteration of these hydrogen bonds, and probable loss of amino terminus interactions, contributing to the increased dimerization of the liganded state. An additional intersubunit hydrogen bond from residue 81, present only in the liganded state, was demonstrated as the largest single effect of ligand binding directly on the subunit interface. Comparison of bovine neurophysins I and II indicates broadly similar mechanisms for both, with the exception in neurophysin II of the absence of Gln55 side chain hydrogen bonds in the unliganded state and a more firmly established loss of amino terminus interactions in the liganded state. Evidence is presented that loop status modulates dimerization via long-range effects on neurophysin conformation involving neighboring Phe22 as a key intermediary.},
doi = {},
journal = {Protein Science},
number = ,
volume = 16,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}