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Enterobacter cloacae rpoS promoter and gene organization
Juana María Navarro-Lloréns1, Esteban Martínez-García, Antonio Tormo
1Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Abstract:
The upstream region of the Enterobacter cloacae strain CECT960 rpoS gene was sequenced. An IS 10R element was found within the nlpD gene, between rpoSp and rpoS. The rpoS promoter, although functional, did not drive transcription of the gene in this strain. However, rpoS transcription depended on this promoter in strains that lacked the insertion sequence in nlpD. rpoSp showed growth-phase-dependent, sigma(S)-independent regulation. Transcription from rpoSp was strongly inhibited by glucose even though it was cAMP-receptor-protein (CRP)-independent. Its functionality was also independent of both integration host factor (IHF) and the alarmone ppGpp. RpoS-dependent resistance to some environmental stresses showed a quantitative response to RpoS levels under some conditions (alkaline pH and high osmolarity) but not others (acidic pH, high temperature, and UV irradiation).