Novel antibiotics: Macrocyclic peptides designed to trap holliday junctions

ORGN 424

Jennifer V.C. Johnston, jjboxer70@yahoo.com1, Lisa A. Liotta, laliotta@hotmail.com1, Irene Medina, imedina_@hotmail.com2, Jennifer L. Robinson, jlrobinson2@hotmail.com1, Chris L. Carroll, chris@the-carrolls.com2, Po-Shen Pan, robertsdsu2003@yahoo.com.tw2, Ricardo Corral, mcalpine@chemistry.sdsu.edu3, Kristina Cook2, and Fiona A. Curtis4. (1) Department of Chemistry, San Diego State University, San Diego, CA 92182, (2) Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, CSL 206, San Diego, CA 92182-1030, (3) Department of Chemistry and Biochemistry, Molecular Biology Institute Center for Applied and Experimental Genomics, San Diego State University, 5500 Campanile Road, 208 CSL, San Diego, CA 92182-1030, (4) Centre for Infectious Diseases, United Kingdom
The development of a new class of antibiotics is described. This class of C-2 symmetrical macrocyclic compounds traps the Holliday Junction (HJ). The HJ is an intermediate formed during site-specific recombination (which is one of several DNA repair mechanisms). The first generation of our C-2 symmetric macrocyclic compounds was tested in both bacterial growth and biochemical assays. These macrocycles demonstrate accumulation of HJ, that is, they trapped the HJ, and demonstrated bacteria growth inhibition. In addition, these compounds were tested as potential anticancer agents and they have given interesting results in mammalian cancer cell studies. A second generation of macrocyclic peptides is in progress. As with the first generation, linear tripeptides and tetrapeptides are synthesized, dimerized, and finally cyclized. The resulting cyclic hexapeptides and octapeptides are C-2 symmetric, thus matching the HJ head-to-tail symmetry, which has proven to be the binding site for these compounds. This symmetry between ligand and receptor is an important principle in the design of our compounds.