Cloning, expression, purification and functional study of lipoprotein FtsB from Streptococcus pyogenes

Abstract:

This study aims to clone ftsb gene from Streptococcus pyogenes 5005, to express and purify FtsB, and to characterize its ferrichrome binding properties in vitro. DNA fragments encoding ftsb was obtained by PCR and inserted into plasmid pGEX4T-1, followed by transformation into Escherichia coli DH5α. The constructed recombinant plasmid was transformed into Escherichia coli BL21 to express FtsB. The conditions used to induce expression were optimized. The protein was purified using affinity chromatography. The ferrichrome binding property was initially characterized, and the binding site was investigated by blocking histidine residues. with DEPC. The 33 kD FtsB was successfully expressed and purified, and the yield was 30 mg/L. The UV-visible spectra showed the FtsB had a visible absorption peak at 425 nm with ferrichrome and that histidine didn’t participate in ferrichrome binding. This approach reports the ferrichrome binding properties and binding site of FtsB, providing theoretical foundations for the further study of ferrichrome transport mechanism in bacteria and the development of drug target and vaccine candidate.