翻译了欧洲标准"EN 14569-2004 Foodstuffs-Microbiological screening for irradiated food using LAL/GNB procedures"。该方法已成功通过实验室验证,通常适用于新鲜的整禽或胸脯、腿、翅膀等器官以及去皮或未去皮的冷冻或...翻译了欧洲标准"EN 14569-2004 Foodstuffs-Microbiological screening for irradiated food using LAL/GNB procedures"。该方法已成功通过实验室验证,通常适用于新鲜的整禽或胸脯、腿、翅膀等器官以及去皮或未去皮的冷冻或冰冻畜体的鉴别。该方法还可以提供待辐照样品微生物学质量的情况,但只能说明样品可能经过电离辐射。展开更多
链霉菌可产生许多具有重要应用价值的次级代谢产物，如抗生素、免疫调节剂、抗肿瘤药物等，它们已经广泛应用于临床医药中。次级代谢产物的生物合成受到转录因子的调控，转录因子通过控制结构基因的转录激活或阻遏解除，决定了表达方式...链霉菌可产生许多具有重要应用价值的次级代谢产物，如抗生素、免疫调节剂、抗肿瘤药物等，它们已经广泛应用于临床医药中。次级代谢产物的生物合成受到转录因子的调控，转录因子通过控制结构基因的转录激活或阻遏解除，决定了表达方式和程度。LuxR家族大ATP结合调控因子（large ATP-binding regulators of the LuxR family, LAL）是一类新的次级代谢途径转录因子，由900～1000个氨基酸残基组成，它的N-端具有Walker A和Walker B模体的ATP／GTP结构域，C．端具有保守的LuxR家族螺旋一转角．螺旋模体的DNA结合域。已在40余种次级代谢产物生物合成基因簇中发现LAL，本文对LAL途径特异性转录调控的研究进展进行综述。展开更多
Nemadectin, a macrocyclic lactone antibiotic, is produced by Streptomyces cyaneogriseus ssp. noncyanogenus. A methoxime derivative of nemadectin, moxdectin, has been widely used to control insect and helminth in anima...Nemadectin, a macrocyclic lactone antibiotic, is produced by Streptomyces cyaneogriseus ssp. noncyanogenus. A methoxime derivative of nemadectin, moxdectin, has been widely used to control insect and helminth in animal health. Despite the importance of nemadectin, little attention has been paid to the regulation of nemadectin biosynthesis, which has hindered efforts to improve nemadectin production via genetic manipulation of regulatory genes. Here, we characterize the function of nemR, the cluster-situated regulatory gene encoding a LAL-family transcriptional regulator, in the nemadectin biosynthesis gene cluster of S. cyaneogriseus ssp. noncyanogenus NMWT1. NemR is shown to be essential for nemadectin production and found to directly activate the transcription of nemA1-1/A1-2/A2, nemC and nemA4/A3/E/D operons, but indirectly activate that of nemG and nemF. A highly conserved sequence 5′-TGGGGTGKATAGGGGGTA-3′(K=T/G) is verified to be essential for NemR binding.Moreover, four novel targets of NemR, including genes encoding an SsgA-like protein(TU94_12730), a methylmalonyl-CoA mutase(TU94_19950), a thioesterase of oligomycin biosynthesis(TU94_22425) and a MFS family transporter(TU94_24835)are identified. Overexpression of nemR significantly increased nemadectin production by 79.9%, in comparison with NMWT1,suggesting that nemR plays an important role in the nemadectin biosynthesis.展开更多
文摘翻译了欧洲标准"EN 14569-2004 Foodstuffs-Microbiological screening for irradiated food using LAL/GNB procedures"。该方法已成功通过实验室验证,通常适用于新鲜的整禽或胸脯、腿、翅膀等器官以及去皮或未去皮的冷冻或冰冻畜体的鉴别。该方法还可以提供待辐照样品微生物学质量的情况,但只能说明样品可能经过电离辐射。
文摘链霉菌可产生许多具有重要应用价值的次级代谢产物，如抗生素、免疫调节剂、抗肿瘤药物等，它们已经广泛应用于临床医药中。次级代谢产物的生物合成受到转录因子的调控，转录因子通过控制结构基因的转录激活或阻遏解除，决定了表达方式和程度。LuxR家族大ATP结合调控因子（large ATP-binding regulators of the LuxR family, LAL）是一类新的次级代谢途径转录因子，由900～1000个氨基酸残基组成，它的N-端具有Walker A和Walker B模体的ATP／GTP结构域，C．端具有保守的LuxR家族螺旋一转角．螺旋模体的DNA结合域。已在40余种次级代谢产物生物合成基因簇中发现LAL，本文对LAL途径特异性转录调控的研究进展进行综述。
基金supported by grants from the National Natural Science Foundation of China (31372006 and 31401814)
文摘Nemadectin, a macrocyclic lactone antibiotic, is produced by Streptomyces cyaneogriseus ssp. noncyanogenus. A methoxime derivative of nemadectin, moxdectin, has been widely used to control insect and helminth in animal health. Despite the importance of nemadectin, little attention has been paid to the regulation of nemadectin biosynthesis, which has hindered efforts to improve nemadectin production via genetic manipulation of regulatory genes. Here, we characterize the function of nemR, the cluster-situated regulatory gene encoding a LAL-family transcriptional regulator, in the nemadectin biosynthesis gene cluster of S. cyaneogriseus ssp. noncyanogenus NMWT1. NemR is shown to be essential for nemadectin production and found to directly activate the transcription of nemA1-1/A1-2/A2, nemC and nemA4/A3/E/D operons, but indirectly activate that of nemG and nemF. A highly conserved sequence 5′-TGGGGTGKATAGGGGGTA-3′(K=T/G) is verified to be essential for NemR binding.Moreover, four novel targets of NemR, including genes encoding an SsgA-like protein(TU94_12730), a methylmalonyl-CoA mutase(TU94_19950), a thioesterase of oligomycin biosynthesis(TU94_22425) and a MFS family transporter(TU94_24835)are identified. Overexpression of nemR significantly increased nemadectin production by 79.9%, in comparison with NMWT1,suggesting that nemR plays an important role in the nemadectin biosynthesis.
