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Volume 398, Issue 2-3 p. 326-332
Research letter
Free Access

BS-RNase tetramers: An example of domain-swapped oligomers

Salvatore Adinolfi

Salvatore Adinolfi

CNR, Centro di Studio di Biocristallographia and Dipartimento di Chimica, Università Federico II di Napoli, Via Mezzocannone 4, 80134 Napoli, Italy

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Renata Piccoli

Renata Piccoli

Dipartimento di Chimica Organica e Biologica, Università Federico II di Napoli, Via Mezzocannone 16, 80134 Napoli, Italy

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Filomena Sica

Filomena Sica

CNR, Centro di Studio di Biocristallographia and Dipartimento di Chimica, Università Federico II di Napoli, Via Mezzocannone 4, 80134 Napoli, Italy

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Lelio Mazzarella

Lelio Mazzarella

CNR, Centro di Studio di Biocristallographia and Dipartimento di Chimica, Università Federico II di Napoli, Via Mezzocannone 4, 80134 Napoli, Italy

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First published: December 02, 1996
Citations: 12
Corresponding author. Fax: (39) (81) 5527771.

Abstract

In the ribonuclease superfamily, dimericity is a unique feature of bovine seminal RNase (BS-RNase). In about two-thirds of native BS-RNase molecules, the two subunits interchange their N-terminal tails, thus generating domain-swapped dimers (MxM), which mostly responsible for enzyme biological activities and allostericity. Higher molecular weight BS-RNase oligomers can also be prepared [Libonati, M. (1969) Ital. J. Biochem. 18, 407–417.]. This paper reports on BS-RNase tetrameric derivatives which were isolated and enzymatically characterized. The data collected and the analysis of the crystal packing of MxM dimers suggested a structural model for tetramer assembly, in which the four subunits are enchained by multiple domain-swapping events.