Blueprints for the rational design of therapeutic mutacin 1140 variants.

Lantibiotics represent a large untapped pipeline of attractive scaffolds for the development of novel antibiotics. Saturation mutagenesis was employed to substitute every amino acid of a lantibiotic called mutacin 1140 (MU1140), creating an unbiased expression library of 418 variants that was used to study the permissiveness to mutagenesis and the "drugability" of several compounds. Contrasting previous reports, the results from this study supported that not all residues involved in lanthionine bridge formation were critical for maintaining optimal activity. While substitutions in lanthionine bridges in Ring A, C, and D invariably lead to inactive variants, permissive substitutions in Abu8 and Ala11 (Ring B) were observed, albeit infrequently. Further, the data generated suggested that the unsaturated bond from Dha5 (Ser5) may not be critically involved in Lipid-II binding but still important for conferring optimal activity. This study identified additional permissive mutations of Ser5, including Ser5His, Ser5Met, Ser5Gln, and Ser5Leu. In contrast, no permissive substitutions were identified for Dhb14, which suggested that this residue may be critical for optimal activity. Novel blueprints are proposed for directing further development of MU1140 variants and other lantibiotics, which may enable the rational design, development, manufacture, and formulation of an entirely new class of anti-infectives.

NanoStore: a concept for logistical improvements of compound handling in high-throughput screening.

Small molecule screening, the systematic encounter of biology space with chemical space, has provoked the emergence of a whole industry that recreates itself by constant iterative improvements to this process. The authors describe an approach to tackle the problem for one of the most time-consuming steps in the execution of a screening campaign, namely, the reformatting of high-throughput screening test compounds from master plates to daughter assay plates used in the execution of the screen. Through an engineered storage procedure, they prepare plates ahead of the screening process with the respective compounds in a ready-to-use format. They show the biological inertness of the method and how it facilitates efficient recovery of compound activity. This uncoupling of normally interconnected processes provides time and compound savings, avoids repeated freeze-thaw cycles of compound solutions, and removes the problems associated with the DMSO sensitivity of certain assays types.