Shapiro L, Agabian-Keshishian N, Hirsch A, Rosen O M
Proc Natl Acad Sci U S A. 1972 May;69(5):1225-9. doi: 10.1073/pnas.69.5.1225.
Caulobacter crescentus goes through a series of morphological changes during its life cycle, including the coincident expression of synthesis of flagella, pili, and receptor sites for DNA bacteriophage. Upon transfer of a mixed population of cells to medium containing lactose as the sole carbon source, these changes were blocked for about 20 hr until beta-galactosidase activity became apparent. The addition of dibutyryl cyclic AMP to the blocked cultures brought about the resumption of cell differentiation, growth, and the appearance of beta-galactosidase activity within 1 hr. Unlike Escherichia coli, the intracellular and extracellular concentrations of cyclic AMP in C. crescentus did not vary under several growth conditions, including catabolite repression. It would appear, therefore, that although there is an effect of cyclic AMP on the induction of beta-galactosidase and differentiation in C. crescentus, regulation of these processes occurs without consistent changes in the cellular level of this nucleotide.
新月柄杆菌在其生命周期中会经历一系列形态变化,包括鞭毛、菌毛以及DNA噬菌体受体位点合成的同步表达。当将混合细胞群体转移到以乳糖作为唯一碳源的培养基中时,这些变化会被阻断约20小时,直到β-半乳糖苷酶活性变得明显。向受阻培养物中添加二丁酰环腺苷酸会在1小时内使细胞分化、生长恢复,并出现β-半乳糖苷酶活性。与大肠杆菌不同,新月柄杆菌细胞内和细胞外的环腺苷酸浓度在包括分解代谢物阻遏在内的几种生长条件下都没有变化。因此,尽管环腺苷酸对新月柄杆菌中β-半乳糖苷酶的诱导和分化有影响,但这些过程的调节在该核苷酸的细胞水平没有一致变化的情况下发生。