Download MendeleyPopulation shift vs induced fit: The case of bovine seminal ribonuclease swapping dimer
Merlino, A., Vitagliano, L., Sica, F., Zagari, A., Mazzarella, L.(2004) Biopolymers 73: 689-695
- PubMed: 15048772
- DOI: https://doi.org/10.1002/bip.20016
- Primary Citation of Related Structures:
1R5C, 1R5D - PubMed Abstract:
Bovine seminal ribonuclease (BS-RNase) is a unique member of the pancreatic-like ribonuclease superfamily. This enzyme exists as two conformational isomers with distinctive biological properties. The structure of the major isomer is characterized by the swapping of the N-terminal segment (MxM BS-RNase). In this article, the crystal structures of the ligand-free MxM BS-RNase and its complex with 2'-deoxycitidylyl(3',5')-2'-deoxyadenosine derived from isomorphous crystals have been refined. Interestingly, the comparison between this novel ligand-free form and the previously published sulfate-bound structure reveals significant differences. In particular, the ligand-free MxM BS-RNase is closer to the structure of MxM BS-RNase productive complexes than to the sulfate-bound form. These results reveal that MxM BS-RNase presents a remarkable flexibility, despite the structural constraints of the interchain disulfide bridges and the swapping of the N-terminal helices. These findings have important implications to the ligand binding mechanism of MxM BS-RNase. Indeed, a population shift rather than a substrate-induced conformational transition may occur in the MxM BS-RNase ligand binding process.
Organizational Affiliation:
Dipartimento di Chimica, Università degli Studi di Napoli Federico II, Via Cynthia, 80126 Napoli, Italy.
