Multi-Factor Regulation of the Master Modulator LeuO for the Cyclic-(Phe-Pro) Signaling Pathway in Vibrio vulnificus

• Published in: Scientific reports Vol. 9; no. 1; pp. 20135 - 14
• Main Authors: Park, Na-Young, Kim, In Hwang, Wen, Yancheng, Lee, Keun-Woo, Lee, Sora, Kim, Jeong-A, Jung, Kwang-Hwan, Lee, Kyu-Ho, Kim, Kun-Soo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.12.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 38/22; 38/23; 38/77; 631/326/325/1506; 631/326/421; 82/1; 96/44; 96/95; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding sites; Calorimetry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA-directed RNA polymerase; Gene deletion; Gene Expression Regulation, Bacterial; Humanities and Social Sciences; Models, Biological; multidisciplinary; Pathogenicity; Pathogens; Peptides, Cyclic - metabolism; Phenylalanine; Proline; Protein Binding; Protein Interaction Domains and Motifs; Regulatory Sequences, Nucleic Acid; RNA polymerase; Science; Science (multidisciplinary); Signal Transduction; Titration; Transcription; Transcription Factors - genetics; Transcription Factors - metabolism; Vibrio vulnificus; Vibrio vulnificus - physiology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-56855-4

LeuO plays the role of a master regulator in the cyclic-L-phenylalanine-L-proline (cFP)-dependent signaling pathway in Vibrio vulnificus . cFP, as shown through isothermal titration calorimetry analysis, binds specifically to the periplasmic domain of ToxR. Binding of cFP triggers a change in the cytoplasmic domain of ToxR, which then activates transcription of leuO encoding a LysR-type regulator. LeuO binds to the region upstream of its own coding sequence, inhibiting its own transcription and maintaining a controlled level of expression. A five-bp deletion in this region abolished expression of LeuO, but a ten-bp deletion did not, suggesting that a DNA bending mechanism is involved in the regulation. Furthermore, binding of RNA polymerase was significantly lower both in the deletion of the ToxR binding site and in the five-bp deletion, but not in the ten-bp deletion, as shown in pull-down assays using an antibody against RNA polymerase subunit α. In summary, multiple factors are involved in control of the expression of LeuO, a master regulator that orchestrates downstream regulators to modulate factors required for survival and pathogenicity of the pathogen.