Mironov Alexander S, Gusarov Ivan, Rafikov Ruslan, Lopez Lubov Errais, Shatalin Konstantin, Kreneva Rimma A, Perumov Daniel A, Nudler Evgeny
State Research Institute of Genetics and Selection of Industrial Microorganisms, 113545, Moscow, Russia.
Cell. 2002 Nov 27;111(5):747-56. doi: 10.1016/s0092-8674(02)01134-0.
Thiamin and riboflavin are precursors of essential coenzymes-thiamin pyrophosphate (TPP) and flavin mononucleotide (FMN)/flavin adenine dinucleotide (FAD), respectively. In Bacillus spp, genes responsible for thiamin and riboflavin biosynthesis are organized in tightly controllable operons. Here, we demonstrate that the feedback regulation of riboflavin and thiamin genes relies on a novel transcription attenuation mechanism. A unique feature of this mechanism is the formation of specific complexes between a conserved leader region of the cognate RNA and FMN or TPP. In each case, the complex allows the termination hairpin to form and interrupt transcription prematurely. Thus, sensing small molecules by nascent RNA controls transcription elongation of riboflavin and thiamin operons and possibly other bacterial operons as well.
硫胺素和核黄素分别是必需辅酶硫胺素焦磷酸（TPP）和黄素单核苷酸（FMN）/黄素腺嘌呤二核苷酸（FAD）的前体。在芽孢杆菌属中，负责硫胺素和核黄素生物合成的基因被组织在严格可控的操纵子中。在此，我们证明核黄素和硫胺素基因的反馈调节依赖于一种新型转录衰减机制。该机制的一个独特特征是同源RNA的保守前导区域与FMN或TPP之间形成特定复合物。在每种情况下，该复合物都能使终止发夹形成并过早中断转录。因此，新生RNA对小分子的感知控制着核黄素和硫胺素操纵子以及可能其他细菌操纵子的转录延伸。
