title: RNase A oligomerization through 3D domain swapping is favoured by a residue located far from the swapping domains.
abstract: Bovine pancreatic ribonuclease A forms 3D domain-swapped oligomers by lyophilization from 40% acetic acid solutions or if subjected to various thermally-induced denaturation procedures. Considering that the intrinsic swapping propensity of bovine seminal RNase, the only member of the pancreatic-type RNase super-family that is dimeric in nature, is decreased from 70 to 30% if Arg80 is substituted by Ser (the corresponding residue in native RNase A), we introduced the opposite mutation in position 80 of the pancreatic enzyme. Our aim was to detect if the RNase A tendency to aggregate through domain swapping could increase. Aggregation of the S80R-RNase A mutant was induced either through the 'classic' acetic acid lyophilization, or through a thermally-induced method. The results indicate that the S80R mutant aggregates to a higher extent than the native protein, and that the increase occurs especially through N-terminal swapping. Additional investigations on the dimeric and multimeric species formed indicate that the S80R mutation increases their stability against regression to monomer, and does not significantly change their structural and functional features.
authors.affiliation: Dipartimento di Scienze della Vita e della Riproduzione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, University of Verona, Strada Le Grazie 8, I-37134 Verona, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Vottariello
authors.forename: Enrico
authors.initials: E
authors.lastname: Giacomelli
authors.forename: Roberta
authors.initials: R
authors.lastname: Frasson
authors.forename: Nicola
authors.initials: N
authors.lastname: Pozzi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: De Filippis
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gotte
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D012259:Ribonuclease, Pancreatic