NasT-Mediated Antitermination Plays an Essential Role in the Regulation of the Assimilatory Nitrate Reductase Operon in Azotobacter vinelandii

• DOI: 10.1128/aem.01720-12
• Publication Date: 2012-07-07T00:37:29Z
• Authors: Baomin Wang; Leland S. Pierson; Christopher Rensing; Malkanthi K. Guna...; Christina Kennedy
• Keywords: Azotobacter vinelandii

Azotobacter vinelandii is a well-studied model system for nitrogen fixation in bacteria. Regulation of A. independent NtrB/NtrC, conserved regulatory proteobacteria. Previous work showed that an ntrC mutation resulted loss induction assimilatory nitrate and nitrite reductases encoded by the nasAB operon. In addition to NtrC, several other proteins, including NasT, protein containing potential RNA-binding domain ANTAR (AmiR NasR transcription antitermination regulators), have been implicated regulation. this work, we characterize sequence upstream nasA identify DNA elements, two NtrC binding sites putative intrinsic transcriptional terminator are potentially involved Our analyses confirm promoter, P(nasA), under control. However, unlike NtrC-regulated promoters enteric bacteria, P(nasA) shows high activity presence ammonium; addition, altered nifA gene background. We discuss implication these results on NtrC-mediated regulation vinelandii. study provides direct evidence regulated NasT-mediated antitermination, which occurs within leader region The also support hypothesis NasT binds promoter proximal hairpin its function, contributes understanding mechanism ANTAR-containing antiterminators.