Identification of Residue Involved in Nucleotidyltransferase Activity of LinA from Staphylococci by Site-directed Mutagenesis

The lincosamide class of antibacterials is widely used for the treatment of a broad spectrum of infections, and one prevalent route of resistance to lincosamides in pathogenic gram-positive cocco is antibiotic modification. Enzymes encoded by lin genes, belonging to nucleotidyltransferase superfamily, catalyze adenylylation to inactivate lincosamides. LinA can adenylylate lincosamides at either 3?-or 4?-OH of the methylthiolincosamide sugar. The crystal structure of LinA/lincomycin has confirmed its active site. However, the residue interacting with nucleotidyl donors remains elusive. Here, we modeled the complex structure of LinA/lincomycin/Mg~(2+)/AMPCPP to reveal a putative pocket for nucleotidyl donors and suggested the residue R45 in this pocket involved in the recognition of donor substrates NTP and catalysis. ITC and enzyme activity assays show that the mutation of residue R45 impairs LinA nucleotidyltransferase activity in vitro. This work provides insights into the molecular mechanism of the nucleotide binding and transferring activity of antibiotic NTases.     

金属有机框架与新型载药体系

金属-有机骨架材料(MOFs)是一类由金属离子与有机配体之间的配位自组装形成的新型多孔复合材料。因其具有高比表面积、可调的尺寸、拓扑结构多样性、合成简便、有机基团易于功能化等优点使其在生物分析、成像、传感、催化、气体存储与分离以及药物运载等领域具有广泛的应用前景。这里通过简要介绍MOFs的研究背景,基于MOFs孔径的药物装载策略以及MOFs药物释放的刺激响应方式,阐述MOFs作为药物递送载体的最新进展,为后期药物载体的设计提供参考。