Chemical synthesis of the third WW domain of TCERG 1 by native chemical ligation

Abstract

The human transcription elongation regulator 1 (TCERG1), with its modular architecture of 3 WW and 6 FF domains, inhibits RNA polymerase II elongation through these WW and FF domains, and interacts with pre-mRNA splicing factors such as SF1, U2 snRNP and U2AF. WW domains are known as the smallest naturally occurring, monomeric, triple stranded, anti-parallel β-sheet structures, generally spanning only about 40 amino acids. The first and second WW domains of TCERG1 have been synthesized and successfully applied for screening cellular targets. In contrast, until now syntheses of the third WW domain yielded oligopeptides with an undefined fold, proving useless for screening cellular targets. This implied that sequence elongation to include the α-helical structure is crucial for proper folding. We describe here the chemical synthesis of such a 53 residue long TCERG1 WW-3 domain sequence that exhibits the typical WW domain fold, and could be useful for discovering cellular targets.