Transcription termination within the regulatory nifLA operon of Klebsiella pneumoniae
1996
Govantes, F. | Santero, E. (Sevilla Univ. (Spain). Dept. de Genetica. Facultad de Biologia)
The effect of premature stop eodons in the nifL gene on the expression of nifA-lacZ operon and protein fusions in Klebsiella pneumoniae was analysed in detail. Our results revealed transcriptional polarity in this operon. By dissecting the operon, intragenic regions containing Rho-dependent transcription terminators have been identified. As shown for other Rhodependent terminators, their cytosine content is much higher than the incidence of guanines. However, other regions of the operon that have this feature did not show termination activity, suggesting that, contrary to previous reports, a correlation between these parameters cannot readily be established. Some of our results also suggested that, in addition to polarity, other mechanisms may prevent expression of nifA when translation of nifL is altered. Their importance for efficient regulation of nitrogen fixation genes is discussed.
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