Rosenkrantz M S, Dingman D W, Sonenshein A L
J Bacteriol. 1985 Oct;164(1):155-64. doi: 10.1128/jb.164.1.155-164.1985.
The activity of aconitase in Bacillus subtilis is greatly reduced in cells cultured in media containing rapidly metabolized carbon sources (e.g., glucose). Thus, expression of this enzyme appears to be subject to a form of catabolite repression. Since the product of the citB gene of B. subtilis is required for aconitase activity, we cloned the wild-type allele of this gene and used this DNA as a probe for transcription of citB in cells grown in various media. The steady-state level of RNA that hybridized to this probe was about 10-fold higher in B. subtilis cells grown in citrate-glutamine medium than in cells grown in glucose-glutamine medium. This result correlates well with the steady-state levels of aconitase activity. Two transcripts were shown to initiate within the cloned DNA; the steady-state level of one of these transcripts varied in the same way as did aconitase activity when cells were grown in media containing different carbon sources. This is the first demonstration of regulation by the carbon source of the level of a vegatative-cell transcript in B. subtilis.
在含有快速代谢碳源（如葡萄糖）的培养基中培养的枯草芽孢杆菌细胞中，乌头酸酶的活性大幅降低。因此，这种酶的表达似乎受到一种分解代谢物阻遏形式的调控。由于枯草芽孢杆菌citB基因的产物是乌头酸酶活性所必需的，我们克隆了该基因的野生型等位基因，并将此DNA用作在各种培养基中生长的细胞中citB转录的探针。与该探针杂交的RNA稳态水平在柠檬酸盐 - 谷氨酰胺培养基中生长的枯草芽孢杆菌细胞中比在葡萄糖 - 谷氨酰胺培养基中生长的细胞中高约10倍。这一结果与乌头酸酶活性的稳态水平密切相关。已显示有两种转录本在克隆的DNA内起始；当细胞在含有不同碳源的培养基中生长时，这些转录本之一的稳态水平与乌头酸酶活性的变化方式相同。这是首次证明枯草芽孢杆菌中营养细胞转录本水平受碳源调控。
