Effects of C-terminal amidation and heptapeptide ring on the biological activities and advanced structure of amurin-9KY, a novel antimicrobial peptide identified from the brown frog, Rana kunyuensis  

作　　者：Fen Zhang Zhi-Lai Guo Yan Chen Li Li Hai-Ning Yu Yi-Peng Wang 

机构地区：[1]Department of Pharmaceutical Sciences,College of Pharmaceutical Sciences,Soochow University,Suzhou Jiangsu 215123,China [2]Department of Bioscience and Biotechnology,Dalian University of Technology,Dalian Liaoning 116023,China [3]School of Life Sciences,Guizhou Normal University,Guiyang Guizhou 550001,China

出　　处：《Zoological Research》2019年第3期198-204,共7页动物学研究（英文）

基　　金：supported by grants from the National Natural Science Foundation of China(31772455);Natural Science Foundation of Jiangsu Province(BK20160336and BK20171214);Natural Science Foundation of College in Jiangsu Province(16KJB350004);Suzhou Science and Technology Development Project(SYN201504 and SNG2017045)

摘　　要：Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain, Yantai, China. In the current study, a 279-bp cD NA sequence encoding a novel antimicrobial peptide（AMP）, designated as amurin-9 KY,was cloned from synthesized double-strand skin cD NA of R. kunyuensis. The amurin-9 KY precursor was composed of 62 amino acid（aa） residues, whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring（Rana box domain） and an amidated C-terminus. These structural characters represent a novel amphibian AMP family. Although amurin-9 KY exhibited high similarity to the already identified amurin-9 AM from R. amurensis,little is known about the structures and activities of amurin-9 family AMPs so far. Therefore, amurin-9 KY and its three derivatives（amurin-9 KY1–3） were designed and synthesized. The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9 KY. Results indicated that C-terminal amidation was essential for antimicrobial activity, whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity. Circular dichroism（CD） spectra showed that the four peptides adopted anα-helical conformation in THF/H2 O（v/v 1:1） solution,but a random coil in aqueous solution. Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity. Scanning electron microscopy（SEM）was also performed to determine the possible bactericidal mechanisms.

关 键 词：Antimicrobial peptides RANA kunyuensis' Amurin-9KY Heptapeptide RING C-TERMINAL AMIDATION STRUCTURE activity relati on ship 

分 类 号：Q[生物学]