title: Structural and thermodynamic bases for the design of pure prolactin receptor antagonists: X-ray structure of Del1-9-G129R-hPRL.
abstract: Competitive antagonists of the human prolactin (hPRL) receptor are a novel class of molecules of potential therapeutic interest in the context of cancer. We recently developed the pure antagonist Del1-9-G129R-hPRL by deleting the nine N-terminal residues of G129R-hPRL, a first generation partial antagonist. We determined the crystallographic structure of Del1-9-G129R-hPRL, which revealed no major change compared with wild type hPRL, indicating that its pure antagonistic properties are intrinsically due to the mutations. To decipher the molecular bases of pure antagonism, we compared the biological, physicochemical, and structural properties of numerous hPRL variants harboring N-terminal or Gly(129) mutations, alone or combined. The pure versus partial antagonistic properties of the multiple hPRL variants could not be correlated to differences in their affinities toward the hPRL receptor, especially at site 2 as determined by surface plasmon resonance. On the contrary, residual agonism of the hPRL variants was found to be inversely correlated to their thermodynamic stability, which was altered by all the Gly(129) mutations but not by those involving the N terminus. We therefore propose that residual agonism can be abolished either by further disrupting hormone site 2-receptor contacts by N-terminal deletion, as in Del1-9-G129R-hPRL, or by stabilizing hPRL and constraining its intrinsic flexibility, as in G129V-hPRL.
authors.affiliation: INSERM U845, Centre de Recherche Croissance et Signalisation, Equipe PRL, GH et Tumeurs, Faculté de Médecine Necker, 156 Rue de Vaugirard, Paris Cedex 15, France.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Jomain
authors.forename: Estelle
authors.initials: E
authors.lastname: Tallet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Broutin
authors.forename: Sylviane
authors.initials: S
authors.lastname: Hoos
authors.forename: Jan
authors.initials: J
authors.lastname: van Agthoven
authors.forename: Arnaud
authors.initials: A
authors.lastname: Ducruix
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kelly
authors.forename: Birthe B
authors.initials: BB
authors.lastname: Kragelund
authors.forename: Patrick
authors.initials: P
authors.lastname: England
authors.forename: Vincent
authors.initials: V
authors.lastname: Goffin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D015195:Drug Design; D005998:Glycine / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011388:Prolactin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011489:Protein Denaturation; D017434:Protein Structure, Tertiary; D051381:Rats; D011981:Receptors, Prolactin / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D040681:Structural Homology, Protein; D013816:Thermodynamics