Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/b, 35131 Padova, Italy.
Biozentrum, University of Basel, CH-4056 Basel, Switzerland; Cellular and Molecular Microbiology (CM2), Faculté des Sciences, Université Libre de Bruxelles (ULB), 12 rue des Professeurs Jeener et Brachet, B-6041 Brussels, Belgium.
Structure. 2022 Nov 3;30(11):1479-1493.e9. doi: 10.1016/j.str.2022.09.004. Epub 2022 Oct 13.
Antimicrobial resistance threatens the eradication of infectious diseases and impairs the efficacy of available therapeutics. The bacterial SOS pathway is a conserved response triggered by genotoxic stresses and represents one of the principal mechanisms that lead to resistance. The RecA recombinase acts as a DNA-damage sensor inducing the autoproteolysis of the transcriptional repressor LexA, thereby derepressing SOS genes that mediate DNA repair, survival to chemotherapy, and hypermutation. The inhibition of such pathway represents a promising strategy for delaying the evolution of antimicrobial resistance. We report the identification, via llama immunization and phage display, of nanobodies that bind LexA with sub-micromolar affinity and block autoproteolysis, repressing SOS response in Escherichia coli. Biophysical characterization of nanobody-LexA complexes revealed that they act by trapping LexA in an inactive conformation and interfering with RecA engagement. Our studies pave the way to the development of new-generation antibiotic adjuvants for the treatment of bacterial infections.
抗菌药物耐药性威胁着传染病的消除，并损害了现有治疗药物的疗效。细菌 SOS 途径是一种由遗传毒性应激引发的保守反应，是导致耐药性的主要机制之一。RecA 重组酶作为一种 DNA 损伤传感器，诱导转录抑制剂 LexA 的自动水解，从而解除 SOS 基因的抑制，介导 DNA 修复、化疗存活和超突变。抑制这种途径是延缓抗菌药物耐药性进化的一种有前途的策略。我们通过羊驼免疫和噬菌体展示鉴定了纳米抗体，它们以亚微米亲和力结合 LexA 并阻断自动水解，从而抑制大肠杆菌中的 SOS 反应。纳米抗体-LexA 复合物的生物物理特性表明，它们通过将 LexA 捕获在非活性构象中并干扰 RecA 结合来发挥作用。我们的研究为开发新一代抗生素佐剂治疗细菌感染铺平了道路。
