Blueprints for the rational design of therapeutic mutacin 1140 variants

Abstract

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.

Complete synthesis of the bicyclic ring of a mutacin analog with orthogonally protected lanthionine via solid‐phase intracyclization

“…The building block lanthionine 7 precursor was synthesized as previously reported, which was then followed by esterification to yield lanthionine OPfp ester 7 . Compound 7 was used as presented in Scheme .…”

“…Prior to the synthesis of bicyclic C/D ring, the AviCys was modified at position 22 to a cysteamine because it was previously shown that the AviCys functional group may not be essential for optimal antimicrobial activity ( Figure 1B). 43 This modification simplifies the synthetic The building block lanthionine 7 precursor was synthesized as previously reported, [10][11][12] which was then followed by esterification to yield lanthionine OPfp ester 7. Compound 7 was used as presented in Scheme 2.…”

“…One of the most interesting aspects of MU1140 is that it acts via a novel mechanism of action termed lipid II abduction . Recently, our group has used saturation mutagenesis to derive general rules for engineering MU1140 analogs that present improved therapeutic properties (eg, improved solubility, metabolic stability, and lower sensitivity to proteolytic degradation) …”

“…[7][8][9] Recently, our group has used saturation mutagenesis to derive general rules for engineering MU1140 analogs that present improved therapeutic properties (eg, improved solubility, metabolic stability, and lower sensitivity to proteolytic degradation). [10][11][12] During natural synthesis, the posttranslational modification of the lantibiotic prepropeptide leads to the formation of thioether rings made of alanine-like derivatives that are cross-linked at their β-car- aziridine ring, 22,23 Mitsunobu chemistry, 24 sulfamidates, 25 chiral dehydroamino acids, 26 and others. [27][28][29][30][31][32][33] Since 2005, naturally occurring lantibiotics and their analogs have been synthesized by solid-phase peptide synthesis (SPPS) with orthogonally protected lanthionine building blocks, and the biological activity of those lantibiotics was confirmed.…”

Pharmacological, Toxicological, and Dose Range Assessment of OG716, a Novel Lantibiotic for the Treatment of Clostridium difficile -Associated Infection

“…While mutacin 1140 (MU1140) is characterized by an excellent overall therapeutic profile (5,12,15), it suffers from limitations that impede its drugability and further clinical development. Building on the lessons learned from previous structure-function studies, key amino acid substitutions were pyramided into compounds that were further characterized in vitro and in vivo (16)(17)(18). Thirty-four years after the initial discovery of MU1140 by Hillman's group (19) and after the screening of over 700 compounds engineered with single and multiple (up to eight) amino acid substitutions in MU1140, two compounds with improved physicochemical, pharmacological, and therapeutic properties, OG716 and OG718, targeting Clostridium difficile in C. difficileassociated disease (CDAD) ( Fig.…”