Transcriptional regulation of puc operon expression in Rhodobacter sphaeroides. Involvement of an integration host factor-binding sequence

• Published in: The Journal of biological chemistry 1993-11, Vol.268 (32), p.24491-24497
• Main Authors: Lee, J K, Wang, S, Eraso, J M, Gardner, J, Kaplan, S
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; Binding Sites; Biological and medical sciences; DNA, Recombinant - metabolism; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Genes, Bacterial; Integration Host Factors; Light-Harvesting Protein Complexes; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Operon; Oxygen - metabolism; Photosystem II Protein Complex; Pigments, Biological - genetics; Rhodobacter sphaeroides; Rhodobacter sphaeroides - genetics; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(20)80552-3

The putative overlapping consensus sequences (-129 to -105) for binding of fumarate nitrate reductase regulator- and integration host factor (IHF)-like proteins to puc operon upstream DNA of Rhodobacter sphaeroides was protected from DNase I digestion by purified Escherichia coli IHF. The binding of E. coli IHF to the purported IHF-binding site in the puc upstream DNA is highly sequence-specific. The recorded binding affinity was significantly lower than that of E. coli IHF to the lambda attP site. Employing site-directed changes in the DNA sequence within the -129 to -105 region, a loss in IHF binding, as monitored through gel retardation analysis, was correlated with alterations in puc operon expression monitored through the use of puc::lacZ transcriptional fusions. These results suggest that the IHF-binding site is involved in repression of puc operon transcription by oxygen as well as modulation of puc operon transcription levels by incident light intensity. Mutations specific to the upstream half of the putative fumarate nitrate reductase regulator-binding site of the puc upstream DNA did not show any physiological effects under the experimental conditions employed. Taken together, these studies reveal that the DNA sequence between -129 to -105 may involve facilitation of the interaction between upstream and downstream cis-acting regulatory sequences involved in puc operon expression.