Background Isocitrate lyase （ICL） was previously demonstrated to play a pivotal role in the intracellular metabolism of Mycobacterium tuberculosis （MTB）. Presently several lines of evidence suggest that ICL from M...Background Isocitrate lyase （ICL） was previously demonstrated to play a pivotal role in the intracellular metabolism of Mycobacterium tuberculosis （MTB）. Presently several lines of evidence suggest that ICL from MTB （MTB-ICL） may play some roles in the interaction between MTB and host macrophage. However, there has been no research on the interaction between MTB-ICL and host macrophage.Methods MTB-icl and M. smegmatis （MS）-icl genes were amplified by polymerase chain reaction （PCR） and cloned into the E. coli-mycobacterium shuttle plasmid pUV15 to obtain recombinant shuttle plasmids pMTB-icl and pMS-icl. Following transformation into MS by electroporation, the expression of pMTB-icl and pMS-icl was verified by reverse transcriptase （RT）-PCR. The expression of recombinant plasmids derived from pUV15 when rMS was phagocytized by macrophage was also verified via fluorescence microscope. Ms 1-2c, rMS-pUV15, rMS-pMS-icl and rMS-pMTB-icl were used to infect RAW264.7 cells and the survival of intracellular MS was monitored by bacterial culture at 0, 24 and 48 hours after infection. The culture supernatants from macrophage infected by Ms 1-2c, rMS-pUV15, rMS-pMS-icl and rMS-pMTB-icl were collected and the interferon （IFN）-y and nitric oxide （NO） concentrations were measured by ELISA or by Griess assay, respectively. The apoptosis of macrophage was assayed by the in situ TUNEL technique.Results RT-PCR showed that both pMTB-icl and pMS-icl could be expressed in MS. Fluorescence microscopic observation showed that recombinant plasmids derived from pUV15 （pUV15-iG） could also be expressed in MS when MS were phagocytized by macrophage. Bacterial culture data demonstrated that rMS-pMTB-icl exhibited significantly increased intracellular survival in the murine macrophage cell line RAW264.7 compared with Ms 1-2c, rMS-pUV15 and rMS-pMS-icl. This increased intracellular survival was not accompanied by the upregulation of IFN-y and NO in host macrophage. But a lower apoptosis rate of macrophages 展开更多
When devoured by macrophages,Mycobacterium tuberculosis remains persistent in macrophages and gains energy through the glyoxylate bypass to maintain its long-term existence in host cells.Therefore it is possible to st...When devoured by macrophages,Mycobacterium tuberculosis remains persistent in macrophages and gains energy through the glyoxylate bypass to maintain its long-term existence in host cells.Therefore it is possible to stop persistent infections by interdicting the glyoxylate bypass in which the isocitrate lyase（ICL） is the key rate-limiting enzyme and a persistence factor.ICL is the target of anti-TB（TB：tubercular） drugs,which could screen ICL out and effectively inhibit the activity of ICL in Mycobacterium tuberculosis,and because of this,anti-TB drugs can be used to kill persistent Mycobacterium tuberculosis.In this study,the ICL gene of the Mycobacterium tuberculosis H37Rv was cloned successfully and recombinant protein with bioactivity was obtained through the enzyme characteristic appraisal.The specific activity of the recombined ICL is 24μmol·mg-1·min-1.The recombined ICL protein was used as the target,and phages which can specifically combine to ICL were screened in the phage 7 peptide library.According to the results of the ELISA and DNA sequence detection,eventually three 7-peptide chains were synthesized.Then the peptide chains were reacted with ICL,respectively,to detect their inhibitory effects on ICL.The results show that all the three 7-peptide chains possessed varying inhibitory effects on the activity of ICL.This study provided lead compounds for the research and development of new peptide anti-TB drugs.展开更多
利用噬菌体肽库筛选与计算机模拟分子对接技术,优化异柠檬酸裂解酶肽类抑制剂的筛选.先通过噬菌体肽库筛选出与异柠檬酸裂解酶(ICL)具有高亲和力的结合肽,再利用Discovery Studio 2.1模拟多肽与ICL蛋白晶体(1F8I)的分子对接,最后用Fmoc...利用噬菌体肽库筛选与计算机模拟分子对接技术,优化异柠檬酸裂解酶肽类抑制剂的筛选.先通过噬菌体肽库筛选出与异柠檬酸裂解酶(ICL)具有高亲和力的结合肽,再利用Discovery Studio 2.1模拟多肽与ICL蛋白晶体(1F8I)的分子对接,最后用Fmoc固相合成法合成多肽,并对其生物活性进行检测.实验结果表明,通过噬菌体肽库筛选得到了29条七肽序列,其中12条可与ICL蛋白晶体成功对接.体外生物活性检测结果显示,得到的12条七肽均对ICL的活性有明显抑制作用(抑制率均超过50%).展开更多
由黑腐皮壳菌(Valsa mali Miyabe et Yamada)引起的苹果树腐烂病严重影响了苹果树的健康生长。异柠檬酸裂解酶是真菌乙醛酸循环中的关键酶,异柠檬酸裂解酶基因(ICL)在真菌生长发育及致病过程中发挥重要作用。本研究在苹果树腐烂病菌基因...由黑腐皮壳菌(Valsa mali Miyabe et Yamada)引起的苹果树腐烂病严重影响了苹果树的健康生长。异柠檬酸裂解酶是真菌乙醛酸循环中的关键酶,异柠檬酸裂解酶基因(ICL)在真菌生长发育及致病过程中发挥重要作用。本研究在苹果树腐烂病菌基因VmICL生物信息学分析的基础上,应用PEG介导原生质体转化法获得了基因VmICL的敲除突变体及回补菌株,解析了VmICL对病菌生长发育、细胞壁完整性、渗透胁迫、碳氮源利用及致病力的影响。研究表明,基因VmICL位于9号染色体,VmICL蛋白在第23-545位氨基酸区域具TIM super family结构域,系统发育分析显示与水稻稻瘟病菌(Magnaporthe grisea)亲缘关系最近。基因VmICL缺失突变体生长速率减慢,分生孢子器产生数量减少,分生孢子萌发延迟;基因VmICL参与维持细胞壁的完整性,但不参与渗透胁迫;基因VmICL正调控碳源吸收,负调控氮源吸收,正调控致病力。总之,基因VmICL参与调控苹果树腐烂病菌的生长发育、细胞壁完整性的维持、碳氮源利用及致病力的发挥。展开更多
基金This work was supported by a grant from the National Natural Science Foundation of China （No. 30600528）.
文摘Background Isocitrate lyase （ICL） was previously demonstrated to play a pivotal role in the intracellular metabolism of Mycobacterium tuberculosis （MTB）. Presently several lines of evidence suggest that ICL from MTB （MTB-ICL） may play some roles in the interaction between MTB and host macrophage. However, there has been no research on the interaction between MTB-ICL and host macrophage.Methods MTB-icl and M. smegmatis （MS）-icl genes were amplified by polymerase chain reaction （PCR） and cloned into the E. coli-mycobacterium shuttle plasmid pUV15 to obtain recombinant shuttle plasmids pMTB-icl and pMS-icl. Following transformation into MS by electroporation, the expression of pMTB-icl and pMS-icl was verified by reverse transcriptase （RT）-PCR. The expression of recombinant plasmids derived from pUV15 when rMS was phagocytized by macrophage was also verified via fluorescence microscope. Ms 1-2c, rMS-pUV15, rMS-pMS-icl and rMS-pMTB-icl were used to infect RAW264.7 cells and the survival of intracellular MS was monitored by bacterial culture at 0, 24 and 48 hours after infection. The culture supernatants from macrophage infected by Ms 1-2c, rMS-pUV15, rMS-pMS-icl and rMS-pMTB-icl were collected and the interferon （IFN）-y and nitric oxide （NO） concentrations were measured by ELISA or by Griess assay, respectively. The apoptosis of macrophage was assayed by the in situ TUNEL technique.Results RT-PCR showed that both pMTB-icl and pMS-icl could be expressed in MS. Fluorescence microscopic observation showed that recombinant plasmids derived from pUV15 （pUV15-iG） could also be expressed in MS when MS were phagocytized by macrophage. Bacterial culture data demonstrated that rMS-pMTB-icl exhibited significantly increased intracellular survival in the murine macrophage cell line RAW264.7 compared with Ms 1-2c, rMS-pUV15 and rMS-pMS-icl. This increased intracellular survival was not accompanied by the upregulation of IFN-y and NO in host macrophage. But a lower apoptosis rate of macrophages
基金Supported by the Technology Development Funds of Education Department of Jilin Province,China(No.2008110)
文摘When devoured by macrophages,Mycobacterium tuberculosis remains persistent in macrophages and gains energy through the glyoxylate bypass to maintain its long-term existence in host cells.Therefore it is possible to stop persistent infections by interdicting the glyoxylate bypass in which the isocitrate lyase（ICL） is the key rate-limiting enzyme and a persistence factor.ICL is the target of anti-TB（TB：tubercular） drugs,which could screen ICL out and effectively inhibit the activity of ICL in Mycobacterium tuberculosis,and because of this,anti-TB drugs can be used to kill persistent Mycobacterium tuberculosis.In this study,the ICL gene of the Mycobacterium tuberculosis H37Rv was cloned successfully and recombinant protein with bioactivity was obtained through the enzyme characteristic appraisal.The specific activity of the recombined ICL is 24μmol·mg-1·min-1.The recombined ICL protein was used as the target,and phages which can specifically combine to ICL were screened in the phage 7 peptide library.According to the results of the ELISA and DNA sequence detection,eventually three 7-peptide chains were synthesized.Then the peptide chains were reacted with ICL,respectively,to detect their inhibitory effects on ICL.The results show that all the three 7-peptide chains possessed varying inhibitory effects on the activity of ICL.This study provided lead compounds for the research and development of new peptide anti-TB drugs.
文摘利用噬菌体肽库筛选与计算机模拟分子对接技术,优化异柠檬酸裂解酶肽类抑制剂的筛选.先通过噬菌体肽库筛选出与异柠檬酸裂解酶(ICL)具有高亲和力的结合肽,再利用Discovery Studio 2.1模拟多肽与ICL蛋白晶体(1F8I)的分子对接,最后用Fmoc固相合成法合成多肽,并对其生物活性进行检测.实验结果表明,通过噬菌体肽库筛选得到了29条七肽序列,其中12条可与ICL蛋白晶体成功对接.体外生物活性检测结果显示,得到的12条七肽均对ICL的活性有明显抑制作用(抑制率均超过50%).
文摘由黑腐皮壳菌(Valsa mali Miyabe et Yamada)引起的苹果树腐烂病严重影响了苹果树的健康生长。异柠檬酸裂解酶是真菌乙醛酸循环中的关键酶,异柠檬酸裂解酶基因(ICL)在真菌生长发育及致病过程中发挥重要作用。本研究在苹果树腐烂病菌基因VmICL生物信息学分析的基础上,应用PEG介导原生质体转化法获得了基因VmICL的敲除突变体及回补菌株,解析了VmICL对病菌生长发育、细胞壁完整性、渗透胁迫、碳氮源利用及致病力的影响。研究表明,基因VmICL位于9号染色体,VmICL蛋白在第23-545位氨基酸区域具TIM super family结构域,系统发育分析显示与水稻稻瘟病菌(Magnaporthe grisea)亲缘关系最近。基因VmICL缺失突变体生长速率减慢,分生孢子器产生数量减少,分生孢子萌发延迟;基因VmICL参与维持细胞壁的完整性,但不参与渗透胁迫;基因VmICL正调控碳源吸收,负调控氮源吸收,正调控致病力。总之,基因VmICL参与调控苹果树腐烂病菌的生长发育、细胞壁完整性的维持、碳氮源利用及致病力的发挥。
