The T-Knot motif revisited

Fabio Polticelli, Stefano Pascarella, Domenico Bordo, Martino Bolognesi, Paolo Ascenzi

Research output: Contribution to journalArticlepeer-review

Abstract

The T-knot scaffold, a disulphide-reinforced structural motif shared by several proteins with very different biological functions, has been defined as 'a stretch of the protein chain which comprises two strands of a β-sheet and three loops, knotted by two disulphides into the shape of the letter T'. In this communication we show that the presence of a central β-sheet is not a required structural feature for proteins sharing the T-knot topology. Moreover, superposition of the three-dimensional structures of representative members of the T-knot family highlights a common and structurally well-defined core, formed by the two knotted disulphides, substituting for a larger residue-based hydrophobic core. These results suggest that folding and stability of the T-knot scaffold mainly depend on the geometry of the two knotted disulphides and on the loop length, and that the secondary structure elements are not a prerequisite for motif formation. Accordingly, a redefinition of the T-knot motif is proposed.

Original languageEnglish
Pages (from-to)1247-1250
Number of pages4
JournalBiological Chemistry
Volume380
Issue number10
DOIs
Publication statusPublished - 1999

Keywords

  • Cystine knot
  • Disulphide bridges
  • T-knot scaffold

ASJC Scopus subject areas

  • Biochemistry

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