Structural and functional characterization of three Type B and C chloramphenicol acetyltransferases from Vibrio species
Structural and functional characterization of three Type B and C chloramphenicol acetyltransferases from Vibrio species
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DOI：
10.1002/pro.3793
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发表时间：
2020-03-01
期刊：
影响因子：
8
通讯作者：
Kuhn, Misty L.
中科院分区：
文献类型：
--
作者：
Alcala, Ashley;Ramirez, Guadalupe;Kuhn, Misty L.
氯霉素乙酰转移酶（CAT）是最早鉴定的抗生素耐药性酶之一，长期以来一直作为模型酶研究质粒介导的抗生素耐药性。这些酶使抗生素氯霉素乙酰化，使其不能抑制细菌蛋白质合成。CAT可以分为不同的类型：A型CAT已知对氯霉素和夫西地酸的抗生素耐药性很重要。B型CAT通常被称为异生物质乙酰转移酶，并采用与链阳性菌素乙酰转移酶相似的结构折叠，已知链阳性菌素乙酰转移酶对链阳性菌素抗生素耐药性至关重要。最近已经鉴定出C型CAT，并且也可以乙酰化氯霉素，但它们在抗生素耐药性中的作用在很大程度上是未知的。在这里，我们的结构和动力学特征的三个弧菌CAT蛋白的非致病性物种（Aliivibrio tagi）和两个重要的人类病原体（霍乱弧菌和创伤弧菌）。我们发现了所有三种蛋白质，包括一种在超级整合子（霍乱弧菌）中的乙酰化氯霉素，但没有乙酰化氨基糖苷类或达福普汀。我们还确定了这些CAT单独和与结晶紫和牛磺胆酸盐的复合物的3D晶体结构。这些化合物是A型CAT的已知抑制剂，但尚未在B型和C型CAT中进行探索。基于序列、结构和动力学分析，我们得出结论，霍乱弧菌和创伤弧菌的CAT属于B型，而A. Kazi CAT属于C型。最终，我们的研究结果提供了一个框架，研究抗生素抗性基因的收购和氯霉素乙酰化弧菌和其他物种的进化。
Chloramphenicol acetyltransferases (CATs) were among the first antibiotic resistance enzymes identified and have long been studied as model enzymes for examining plasmid-mediated antibiotic resistance. These enzymes acetylate the antibiotic chloramphenicol, which renders it incapable of inhibiting bacterial protein synthesis. CATs can be classified into different types: Type A CATs are known to be important for antibiotic resistance to chloramphenicol and fusidic acid. Type B CATs are often called xenobiotic acetyltransferases and adopt a similar structural fold to streptogramin acetyltransferases, which are known to be critical for streptogramin antibiotic resistance. Type C CATs have recently been identified and can also acetylate chloramphenicol, but their roles in antibiotic resistance are largely unknown. Here, we structurally and kinetically characterized three Vibrio CAT proteins from a nonpathogenic species (Aliivibrio fisheri) and two important human pathogens (Vibrio cholerae and Vibrio vulnificus). We found all three proteins, including one in a superintegron (V. cholerae), acetylated chloramphenicol, but did not acetylate aminoglycosides or dalfopristin. We also determined the 3D crystal structures of these CATs alone and in complex with crystal violet and taurocholate. These compounds are known inhibitors of Type A CATs, but have not been explored in Type B and Type C CATs. Based on sequence, structure, and kinetic analysis, we concluded that the V. cholerae and V. vulnificus CATs belong to the Type B class and the A. fisheri CAT belongs to the Type C class. Ultimately, our results provide a framework for studying the evolution of antibiotic resistance gene acquisition and chloramphenicol acetylation in Vibrio and other species.