Bacteriophage T4 MotA Activator and the β-Flap Tip of RNA Polymerase Target the Same Set of σ70 Carboxyl-terminal Residues

Abstract

Background: Transcriptional activators interact with RNA polymerase to redefine gene expression. Results: A phage activator engages a region of the specificity factor of E. coli RNA polymerase, which is normally bound by another portion of RNA polymerase. Conclusion: Using an activator/co-activator system, the phage hijacks the host RNA polymerase. Significance: Small transcriptional factors acting on defined local regions of RNA polymerase can fundamentally change gene expression.

Visualizing the phage T4 activated transcription complex of DNA andE. coliRNA polymerase

“…After autoradiography, levels of RNA products were quantified using a Powerlook 100XL densitometer and Quantity One software from Bio-Rad, Inc. The ratios of abortive products to full length RNA were determined as previously described ( 35 ).…”

“…Furthermore, in previous work we have biochemically mapped the orientation of MotA relative to the DNA within the σ-appropriated complex using MotA conjugated with the chemical cleaving reagent iron bromoacetamidobenzyl-EDTA (FeBABE) ( 34 ). This work then provides a framework within which to incorporate other analyses indicating how MotA NTD interacts with σ 70 H5 ( 16 , 35 ). Rational combination of these heterogeneous data affords a complete snapshot of the protein-protein and protein-DNA interactions within the σ appropriation process.…”

Architecture of the Bacteriophage T4 Activator MotA/Promoter DNA Interaction during Sigma Appropriation

“…This remodeling also prevents the interaction of Region 4 and the C terminus of 70 , H5, with the ␤-flap of core RNAP. Instead, in the -appropriated complex, H5 interacts with MotA NTD (12,13) (Fig. 7).…”

Transcription regulation mechanisms of bacteriophages

“…9 Single amino acid substitutions based on the C-terminus of σ 70 determined the interaction between σ 70 residues; it was also found that MotA was negatively affected by the substitution of several residues (e.g., Leucine 607) with alanine. 13 Activator MotA binds more tightly to the promoter in the presence of the co-activator AsiA and RNAP.…”