title: Potent antimicrobial small molecules screened as inhibitors of tyrosine recombinases and Holliday junction-resolving enzymes.
abstract: Holliday junctions (HJs) are critical intermediates in many recombination-dependent DNA repair pathways. Our lab has previously identified several hexameric peptides that target HJ intermediates formed in DNA recombination reactions. One of the most potent peptides, WRWYCR, is active as a homodimer and has shown bactericidal activity partly because of its ability to interfere with DNA repair proteins that act upon HJs. To increase the possibility of developing a therapeutic targeting DNA repair, we searched for small molecule inhibitors that were functional surrogates of the peptides. Initial screens of heterocyclic small molecule libraries resulted in the identification of several N-methyl aminocyclic thiourea inhibitors. Like the peptides, these inhibitors trapped HJs formed during recombination reactions in vitro, but were less potent than the peptides in biochemical assays and had little antibacterial activity. In this study, we describe the screening of a second set of libraries containing somewhat larger and more symmetrical scaffolds in an effort to mimic the symmetry of a WRWYCR homodimer and its target. From this screen, we identified several pyrrolidine bis-cyclic guanidine inhibitors that also interfere with processing of HJs in vitro and are potent inhibitors of Gram-negative and especially Gram-positive bacterial growth. These molecules are proof-of-principle of a class of compounds with novel activities, which may in the future be developed into a new class of antibiotics that will expand the available choices for therapy against drug-resistant bacteria.
authors.affiliation: Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, CA 92182, USA.
authors.forename: Marc C
authors.initials: MC
authors.lastname: Rideout
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Boldt
authors.forename: Gabriel
authors.initials: G
authors.lastname: Vahi-Ferguson
authors.forename: Peter
authors.initials: P
authors.lastname: Salamon
authors.forename: Adel
authors.initials: A
authors.lastname: Nefzi
authors.forename: John M
authors.initials: JM
authors.lastname: Ostresh
authors.forename: Marc
authors.initials: M
authors.lastname: Giulianotti
authors.forename: Clemencia
authors.initials: C
authors.lastname: Pinilla
authors.forename: Anca M
authors.initials: AM
authors.lastname: Segall
mesh_terms: D015075:2-Aminopurine / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D010582:Bacteriophage lambda / Q000201:enzymology; D004265:DNA Helicases / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D019791:Guanidine / Q000737:chemistry; D045565:Holliday Junction Resolvases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D011759:Pyrrolidines / Q000737:chemistry; D011995:Recombination, Genetic / Q000187:drug effects; D014443:Tyrosine
chemical_list: D000890:Anti-Infective Agents; D004791:Enzyme Inhibitors; D011759:Pyrrolidines; D014443:Tyrosine; D015075:2-Aminopurine; D045565:Holliday Junction Resolvases; D004265:DNA Helicases; D019791:Guanidine; C032519:pyrrolidine