Research School of Chemistry, The Australian National University, Canberra, ACT 0200, Australia.
CSIRO Entomology, Black Mountain, ACT 2601, Australia.
Sci Rep. 2017 Jan 11;7:40357. doi: 10.1038/srep40357.
Metallo-β-lactamases (MBLs) with activity towards a broad-spectrum of β-lactam antibiotics have become a major threat to public health, not least due to their ability to rapidly adapt their substrate preference. In this study, the capability of the MBL AIM-1 to evade antibiotic pressure by introducing specific mutations was probed by two alternative methods, i.e. site-saturation mutagenesis (SSM) of active site residues and in vitro evolution. Both approaches demonstrated that a single mutation in AIM-1 can greatly enhance a pathogen's resistance towards broad spectrum antibiotics without significantly compromising the catalytic efficiency of the enzyme. Importantly, the evolution experiments demonstrated that relevant amino acids are not necessarily in close proximity to the catalytic centre of the enzyme. This observation is a powerful demonstration that MBLs have a diverse array of possibilities to adapt to new selection pressures, avenues that cannot easily be predicted from a crystal structure alone.
金属β-内酰胺酶（MBLs）对广谱β-内酰胺类抗生素具有活性，已成为公共卫生的主要威胁，尤其是由于它们能够快速改变其底物偏好。在这项研究中，通过两种替代方法即活性位点残基的定点饱和突变（SSM）和体外进化，探究了 MBL AIM-1 引入特定突变以逃避抗生素压力的能力。这两种方法都表明，AIM-1 中的单个突变可以极大地增强病原体对广谱抗生素的耐药性，而不会显著降低酶的催化效率。重要的是，进化实验表明，相关氨基酸不一定与酶的催化中心接近。这一观察结果有力地证明了 MBL 具有多种多样的适应新选择压力的可能性，仅凭晶体结构无法轻易预测这些途径。
