CRISPR/Cas系统间隔序列同源质粒耐药信息与志贺菌耐药的关系

Information on the drug resistance of plasmids that are homologous to spacers in a CRISPR/Cas system and its relationship to information on the drug resistance of Shigella

目的比较志贺菌耐药信息与其spacer同源质粒或噬菌体耐药信息的关系。方法应用CRISPR Target和BLAST寻找spacer同源质粒和噬菌体,根据登记号在NCBI或GenBank中寻找目标质粒或噬菌体上的耐药信息;应用Bioedit软件寻找GenBank中志贺菌的的耐药信息。结果数据库及临床分离株志贺菌共52条spacer中有7个spacer与4个携带耐药基因的质粒同源;间隔序列CRISPR2-mel-3同源质粒pUMNF18_IncFV及携带该间隔序列的志贺菌mel-ss1998011/zz、mel-ss1998024/zz、mel-sf2005082/sx、mel-sf2013004/bj均含有相同耐药基因blaTEM、aadA2和dfrA12,间隔序列CRISPR-Q1-S1、CRISPR-Q4-S1同源的质粒pM5A24P及该间隔序列所在志贺菌sd1012均携带耐药基因ampC和tetB;间隔序列CRISPR3-mel-33同源质粒plasmid:5与该间隔序列所在志贺菌mel-sf2000102/zz均携带相同耐药基因ampH、mrdA,且二者均携带毒力相关基因yafO、yafN、virK、ldrB、ychO。该质粒上还存在I-F型CRISPR/Cas系统。结论志贺菌spacer同源质粒与该菌耐药信息分布存在相似性;CRISPR可能对志贺菌的耐药和毒力实现共调控。因此推测在最初前间隔序列整合到CRISPR基因座形成一个新的间隔序列的过程中,志贺菌可能将携带前间隔序列外源遗传物质的其他基因片段如耐药基因和毒力基因也整合到志贺菌基因组中,影响其生存及性状。

Objective To compare drug resistance between Shigellastrains and spacers homologous to plasmids or phages. Methods CRISPR Target and BLAST were both used to search for plasmids or phages that are homologous to spacers,and then their accession numbers were used to find information related to their drug resistance.The drug resistance of Shigellastrains in GenBank was detected with Bioedit. Results Seven of 52 spacers were homologous to 4plasmids that carry information related to drug resistance.The drug resistance genes blaTEM,aadA2,and dfrA12 were detected in Shigellastrains（mel-ss1998011/zz,mel-ss1998024/zz,mel-sf2005082/sx,and mel-sf2013004/bj）and a spacer（CRISPR2-mel-3）homologous to plasmid pUMNF18_IncFV.Similarly,the drug resistance genes ampCand tetB were detected in a Shigella strain（sd1012）and spacers（CRISPR-Q1-S1 and CRISPR-Q4-S1）homologous to plasmid pM5A24 P.In addition,the drug resistance genes ampH and mrdA were both detected in a Shigella strain（melsf2000102/zz）and a spacer（CRISPR3-mel-33）homologous to plasmid 5.Intriguingly,both carried the virulence genes yafO,yafN,virK,ldrB,and ychO.Moreover,a type I-F CRISPR/Cas system was found in this plasmid. Conclusion Shigella strains and plasmids that are homologous to spacers contain similar information on drug resistance.CRISPR may co-regulate the drug resistance and virulence of Shigella.In the process of acquiring new spacers,Shigella may integrate other fragments of exogenous genetic material that carry protospacers into its genome.This finding may provide clues to the relationship between the CRISPR/Cas system and the drug resistance or virulence of bacteria.