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[目的]细菌的sahH基因编码S-腺苷同型半胱氨酸水解酶(SahH),该酶参与细菌的甲硫氨酸循环(AMC),调控细菌的多种生理功能.[方法]通过构建重组表达质粒pET28a-Bru-sahH和pET28a-Pse-sahH,分别表达布鲁菌(Brucella abortus)S2308株和铜绿假单胞菌(Pseudomonasaeruginosa)PA01株的SahH重组蛋白Bru-SahH和Pse-SahH.将纯化后的Bru-SahH、Pse-SahH以及我们前期表达纯化的禽致病性大肠杆菌(avian pathogenic Escherichia coli,APEC)的Pfs和LuxS蛋白,分别在体外催化S-腺苷同型半胱氨酸(SAH),通过对产物同型半胱氨酸(HCY)的浓度测定,评价不同重组蛋白的催化活性,并对催化底物时产生的自诱导分子2(AI-2)活性进行检测.[结果]Bru-SahH和Pse-SahH分别催化1 mmol·L-1 SAH生成38和47tμmol·L-1 HCY,而APEC的Pfs和LuxS蛋白能催化相同浓度的SAH产生401 μmol·L-1 HCY.运用哈维弧菌BB170检测上述底物的AI-2活性,结果表明只有同时采用AEPC的Pfs和LuxS蛋白催化SAH,才能形成有活性的AI-2分子,而Bru-SahH和Pce-SahH均不能催化SAH形成活性AI-2分子.[结论]Bru-SahH能催化SAH生成HCY,为进一步研究sahH在布鲁菌感染过程中的作用提供依据.“,”[Objectives]The S-adenosylhomocysteine hydrolase (SahH)is encoded by sahH gene in Brucella abortus.SahH is a key enzyme in activated methionine cycle (AMC),which plays an important role in regulation of bacterial physiological functions.[Methods]In this study,the four recombinant proteins Bru-SahH (from B.abortus),Pse-SahH (from Pseudomonas aeruginosa),APEC-LuxS and APEC-Pfs (from avian pathogenic Escherichia coli) were purified respectively.The catalytic activity of the four recombinant proteins were evaluated by catalyzing substrate S-adenosylhomocysteine(SAH) to produce homocysteine (HCY)in vitro.[Results]The results showed that Bru-SahH or Pse-SahH could catalyze SAH (1 mmol· L-1)to produce 38 μmol· L-1 or 47 μmol· L-1 HCY,respectively,while APEC-LuxS and APEC-Pfs are 401 μmol· L-1.Furthermore,for confirming whether recombinant proteins could catalyze SAH to produce AI-2 or not,the detection of AI-2 bioassay by Vibrio harveyi strain BB170 was performed.The results demonstrated that APEC-LuxS and APEC-Pfs could catalyze SAH to produce AI-2,while Bru-SahH or Pse-SahH could not.[Conclusions]These findings will benefit for future studies on SahH regulation in Brucella abortus.