A Role for the Conserved GAFTGA Motif of AAA+ Transcription Activators in Sensing Promoter DNA Conformation

• Published in: The Journal of biological chemistry 2007-01, Vol.282 (2), p.1087-1097
• Main Authors: Dago, Angel Ernesto, Wigneshweraraj, Siva R., Buck, Martin, Morett, Enrique
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Sequence; Bacterial Proteins - genetics; Bradyrhizobium - genetics; Conserved Sequence; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Gene Expression Regulation, Bacterial; Klebsiella pneumoniae - genetics; Metalloendopeptidases - chemistry; Metalloendopeptidases - genetics; Metalloendopeptidases - metabolism; Molecular Sequence Data; Mutagenesis, Site-Directed; Nucleic Acid Conformation; Promoter Regions, Genetic - genetics; Protein Structure, Tertiary; RNA Polymerase Sigma 54 - genetics; RNA Polymerase Sigma 54 - metabolism; Sigma Factor - genetics; Sigma Factor - metabolism; Trans-Activators - chemistry; Trans-Activators - genetics; Transcription Factors - genetics; Transcriptional Activation - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M608715200

Transcription from σ54-dependent bacterial promoters can be regarded as a second paradigm for bacterial gene transcription. The initial σ54-RNA polymerase (RNAP)·promoter complex, the closed complex, is transcriptionally silent. The transcriptionally proficient σ54-RNAP·promoter complex, the open complex, is formed upon remodeling of the closed complex by actions of a specialized activator protein that belongs to the AAA (ATPases associated with various cellular activities) protein family in an ATP hydrolysis-dependent reaction. The integrity of a highly conserved signature motif in the AAA activator (known as the GAFTGA motif) is important for the remodeling activity of the AAA activator and for open complex formation. We now provide evidence that the invariant threo-nine residue of the GAFTGA motif plays a role in sensing the DNA downstream of the σ54-RNAP-binding site and in coupling this information to σ54-RNAP via the conserved regulatory Region I domain of σ54 during open complex formation.