Chemical synthesis of plant pollen tube attractant proteins by KAHA ligation.

The synthesis of secreted cysteine-rich proteins (CRPs) is a long-standing challenge due to protein aggregation and premature formation of inter- and intramolecular disulfide bonds. Chemical synthesis provides reduced CRPs with a higher purity, which is advantageous for folding and isolation. Herein, we report the chemical synthesis of pollen tube attractant CRPs LURE (TfLURE) and LURE (TcLURE) and their chimeric analogues α-ketoacid-hydroxylamine (KAHA) ligation. The bioactivity of chemically synthesized TfLURE protein was shown to be comparable to expressed recombinant protein through assay. The convergent protein synthesis approach is beneficial for preparing these small protein variants efficiently.