Ashley Clemente
Fordham University
Dissecting the Interaction Between Griselimycin and the Mycobacterium Smegmatis Sliding Clamp Protein
DNA replication is essential for cellular growth and survival, making it an attractive antibiotic target. Replication is carried out by the replisome, a molecular machine composed of multiple proteins that coordinate rapid DNA synthesis. One critical interaction within the replisome is between the sliding clamp protein (DnaN) and DNA polymerase. Polymerases interact with DnaN through a short segment of five or six amino acids called a clamp-binding motif. This interaction mode is advantageous for antibiotic development because small peptides can mimic clamp-binding motifs and prevent the sliding clamp from interacting with DNA polymerases. Griselimycin, a naturally occurring antibiotic peptide, inhibits the interaction between DnaN and DNA polymerases in mycobacteria. Griselimycin binds DnaN similarly to clamp-binding motifs, outcompeting DNA polymerases. To develop more potent DnaN inhibitors, we dissected griselimycin’s interaction with the Mycobacterium smegmatis clamp by synthesizing peptide variants. We synthesized and tested over twenty griselimycin variants for their ability to disrupt clamp binding and inhibit bacterial growth. Our results show some chemical features are critical for strong clamp interaction, while others have minimal impact on binding affinity. Certain variants retained activity despite simplified structures, suggesting core elements required for clamp inhibition can be preserved in streamlined analogs for rational antibiotic design.
DNA replication is essential for cellular growth and survival, making it an attractive antibiotic target. Replication is carried out by the replisome, a molecular machine composed of multiple proteins that coordinate rapid DNA synthesis. One critical interaction within the replisome is between the sliding clamp protein (DnaN) and DNA polymerase. Polymerases interact with DnaN through a short segment of five or six amino acids called a clamp-binding motif. This interaction mode is advantageous for antibiotic development because small peptides can mimic clamp-binding motifs and prevent the sliding clamp from interacting with DNA polymerases. Griselimycin, a naturally occurring antibiotic peptide, inhibits the interaction between DnaN and DNA polymerases in mycobacteria. Griselimycin binds DnaN similarly to clamp-binding motifs, outcompeting DNA polymerases. To develop more potent DnaN inhibitors, we dissected griselimycin’s interaction with the Mycobacterium smegmatis clamp by synthesizing peptide variants. We synthesized and tested over twenty griselimycin variants for their ability to disrupt clamp binding and inhibit bacterial growth. Our results show some chemical features are critical for strong clamp interaction, while others have minimal impact on binding affinity. Certain variants retained activity despite simplified structures, suggesting core elements required for clamp inhibition can be preserved in streamlined analogs for rational antibiotic design.
