Sekowska A, Bertin P, Danchin A
Régulation de l'Expression Génétique, Institut Pasteur, Paris, France.
Mol Microbiol. 1998 Aug;29(3):851-8. doi: 10.1046/j.1365-2958.1998.00979.x.
The ubiquitous polyamines fulfil a variety of functions in all three kingdoms of life. However, little is known about the biosynthesis of these compounds in Gram-positive bacteria. We show that, in Bacillus subtilis, there is a single pathway to polyamines, starting from arginine, with agmatine as an intermediate. We first identified the structural gene of arginine decarboxylase, speA (formerly cad), and then described the speE speB operon, directing synthesis of spermidine synthase and agmatinase. This operon is transcribed into two messenger RNAs, a major one for the speE gene and a minor one for both speEand speB. The promoter of the operon was identified upstream from the speE gene by primer extension analysis. Transcription of this operon indicated that the level of agmatinase synthesis is very low, thus allowing a stringent control on the synthesis of putrescine and, therefore, of all polyamines. This is consistent with the level of polyamines measured in the cell.
普遍存在的多胺在生物界的所有三个域中都发挥着多种功能。然而，对于革兰氏阳性菌中这些化合物的生物合成知之甚少。我们发现，在枯草芽孢杆菌中，存在一条从精氨酸开始、以胍丁胺为中间产物的多胺合成途径。我们首先鉴定了精氨酸脱羧酶的结构基因speA（以前称为cad），然后描述了speE speB操纵子，该操纵子指导亚精胺合酶和胍丁胺酶的合成。这个操纵子转录成两种信使RNA，一种主要用于speE基因，另一种次要的用于speE和speB。通过引物延伸分析在speE基因上游鉴定了该操纵子的启动子。该操纵子的转录表明胍丁胺酶的合成水平非常低，从而对腐胺以及所有多胺的合成进行严格控制。这与在细胞中测得的多胺水平一致。
