title: Chain termini cross-talk in the swapping process of bovine pancreatic ribonuclease.
abstract: 3D domain swapping is the process by which two or more protein molecules exchange part of their structure to form intertwined dimers or higher oligomers. Bovine pancreatic ribonuclease (RNase A) is able to swap the N-terminal α-helix (residues 1-13) and/or the C-terminal β-strand (residues 116-124), thus forming a variety of oligomers, including two different dimers. Cis-trans isomerization of the Asn113-Pro114 peptide group was observed when the protein formed the C-terminal swapped dimer. To study the effect of the substitution of Pro114 on the swapping process of RNase A, we have prepared and characterized the P114A monomeric and dimeric variants of the enzyme. In contrast with previous reports, the crystal structure and NMR data on the monomer reveals a mixed cis-trans conformation for the Asn113-Ala114 peptide group, whereas the X-ray structure of the C-terminal swapped dimer of the variant is very close to that of the corresponding dimer of RNase A. The mutation at the C-terminus affects the capability of the N-terminal α-helix to swap and the stability of both dimeric forms. The present results underscore the importance of the hydration shell in determining the cross-talk between the chain termini in the swapping process of RNase A.
authors.affiliation: Department of Chemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia, I-80126 Naples, Italy.
authors.forename: Antonello
authors.initials: A
authors.lastname: Merlino
authors.forename: Delia
authors.initials: D
authors.lastname: Picone
authors.forename: Carmine
authors.initials: C
authors.lastname: Ercole
authors.forename: Anna
authors.initials: A
authors.lastname: Balsamo
authors.forename: Filomena
authors.initials: F
authors.lastname: Sica
mesh_terms: D000818:Animals; D002417:Cattle; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D017510:Protein Folding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D012259:Ribonuclease, Pancreatic