IN VITRO STUDIES ON THE IMPACT OF THE LIPID COMPONENT OF NOVEL LIPOPEPTIDES ON BIOLOGICAL ACTIVITY
Westley Cruces, Brandi Betts-Obregon, Andrew Tsin, George R. Negrete.
The University of Texas at San Antonio, San Antonio, TX.
Bacterial diseases are known to affect animals, plants, and humans. A devastating bacterium that causes citrus greening has decreased Florida’s citrus production. This disease has drawn attention from the scientific community. Lipopeptides have been shown to have antibiotic properties. Our laboratory has been synthesizing novel cysteine-derived lipid analogs (CLAs) as potential antibiotics by studying the structure-activity relationships of lipopeptides against the bacteria and human adult retinal pigment epithelial cells (ARPE19). The target antibiotics share a thiazolidine core with an acryloyl group that can be coupled with alkyl or aryl thiols via conjugate addition and carboxylic acid and aryl nitro groups. The latter can be reduced to an amine so that the carboxyl and amino groups can be employed to append to peptide chains and fluorophores via peptide coupling methods. Constructs with lipid, peptide, and fluorescent labels can be employed for bioactivity, binding, and localization studies with bacterial and other cell lines. Our CLAs will be dissolved in serum-free DMEM: F12 and placed into bacteria and ARPE19 culture media at 37 oC and 5% CO2 for 24, 48, and 72 hours. After each time interval, conditioned media (CM) will be removed and cells will be harvested and counted for cell viability using the trypan blue dye exclusion method. To study CLA's binding and entry into cells, bacteria and ARPE19 cells will be fixed for Ziess 710 confocal imaging to determine the location of the CLAs.