title: The complex binding mode of the peptide hormone H2 relaxin to its receptor RXFP1.
abstract: H2 relaxin activates the relaxin family peptide receptor-1 (RXFP1), a class A G-protein coupled receptor, by a poorly understood mechanism. The ectodomain of RXFP1 comprises an N-terminal LDLa module, essential for activation, tethered to a leucine-rich repeat (LRR) domain by a 32-residue linker. H2 relaxin is hypothesized to bind with high affinity to the LRR domain enabling the LDLa module to bind and activate the transmembrane domain of RXFP1. Here we define a relaxin-binding site on the LDLa-LRR linker, essential for the high affinity of H2 relaxin for the ectodomain of RXFP1, and show that residues within the LDLa-LRR linker are critical for receptor activation. We propose H2 relaxin binds and stabilizes a helical conformation of the LDLa-LRR linker that positions residues of both the linker and the LDLa module to bind the transmembrane domain and activate RXFP1.
authors.affiliation: Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.|Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Ashish
authors.initials: A
authors.lastname: Sethi
authors.affiliation: Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.|Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.|Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Shoni
authors.initials: S
authors.lastname: Bruell
authors.affiliation: Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.|School of Chemistry, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Nitin
authors.initials: N
authors.lastname: Patil
authors.affiliation: School of Chemistry, The University of Melbourne, Victoria 3010, Australia.|Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Mohammed Akhter
authors.identifier: http://orcid.org/0000-0002-9961-0006
authors.initials: MA
authors.lastname: Hossain
authors.affiliation: Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.|Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Scott
authors.affiliation: Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.|Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Petrie
authors.affiliation: Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.|Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Ross A D
authors.initials: RAD
authors.lastname: Bathgate
authors.affiliation: Department of Biochemistry &Molecular Biology, The University of Melbourne, Victoria 3010, Australia.|Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Paul R
authors.identifier: http://orcid.org/0000-0002-0323-449X
authors.initials: PR
authors.lastname: Gooley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018000:Receptors, Peptide / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012065:Relaxin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
chemical_list: C095068:RLN2 protein, human; C417543:RXFP1 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D011994:Recombinant Proteins; D012065:Relaxin