Nosiheptide is a highly modified thiopeptide antibiotic synthesized by the bacteria <i>Streptomyces </i><i>actuosus</i>. Researching new thiopeptide antibiotics is becoming more important due to the rise of antibiotic resistance all over the world. In order to be able to produce antibiotics for human use, the biosynthetic pathway must be understood in order to optimize production methods. This paper explains the importance of leader peptide in substrate recognition by NosK. NosK was overexpressed in E. coli and purified on a nickel column. Peptide variants of the original NosK substrate were synthesized by SPPS. Several peptides were synthesized with different lengths of the leader peptide segment in order to run enzyme assays and compare relative amounts of product formation. The turnover of these peptides was compared to the turnover of the real substrate for NosK. The determination of the activity of these peptides came from assays quenched at several time points that were then analyzed by LCMS. It was found that the leader peptide is not necessary, but does help in recognition of the substrate by NosK. Continued research is aimed at finding the minimum length the leader peptide could be to still have maximum recognition by NosK.

Importance of the leader peptide in recognition by NosK

2019 Spring National Meeting

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