Making ends meet: chemically mediated circularization of recombinant proteins

Area of Science:

• Biochemistry
• Synthetic Biology
• Peptide Chemistry

Background:

• Cyclotides are a class of plant-derived cyclic peptides with diverse biological activities.
• Traditional methods for synthesizing cyclic peptides often involve complex procedures or protein splicing elements.

Purpose of the Study:

• To develop a novel and efficient method for the semi-synthesis of cyclotides.
• To demonstrate the feasibility of creating circular miniproteins from linear bacterial peptide precursors.

Main Methods:

• Utilized a selective N→S acyl transfer reaction for peptide cyclization.
• Employed a linear precursor peptide of bacterial origin.
• Appended N-terminal cysteine and a thiol-labile C-terminal Gly-Cys motif.

Main Results:

• Successfully achieved the semi-synthesis of the plant cyclotide kalata B1.
• Demonstrated the first synthesis of a ribosomally derived circular miniprotein without protein splicing.
• The N→S acyl transfer reaction proved effective for cyclization.

Conclusions:

• The developed N→S acyl transfer strategy offers a new route for cyclic peptide synthesis.
• This method provides a simplified approach to generating circular miniproteins.
• Opens avenues for the production of engineered cyclic peptides.