NusA directly interacts with antitermination factor Q from phage λ

• Published in: Scientific reports 2020-04, Vol.10 (1), p.6607-6607, Article 6607
• Main Authors: Dudenhoeffer, Benjamin R., Borggraefe, Jan, Schweimer, Kristian, Knauer, Stefan H.
• Format: Article
• Language: English
• Subjects: 631/337/572; 631/45/56; 631/535/878/1263; Bacteriophage lambda - metabolism; Binding Sites; Crystal structure; DNA-Directed RNA Polymerases - metabolism; Escherichia coli - genetics; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - metabolism; Gene Expression Regulation, Bacterial; Gene regulation; Humanities and Social Sciences; Magnetic resonance spectroscopy; Models, Molecular; multidisciplinary; N-Terminus; NMR; Nuclear magnetic resonance; Phages; Protein Binding; Protein Domains; Science; Science (multidisciplinary); Solutions; Transcription elongation; Transcription Elongation, Genetic; Transcription termination; Transcriptional Elongation Factors - chemistry; Transcriptional Elongation Factors - metabolism; Viral Proteins - chemistry; Viral Proteins - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-63523-5

Antitermination (AT) is a ubiquitous principle in the regulation of bacterial transcription to suppress termination signals. In phage λ antiterminator protein Q controls the expression of the phage’s late genes with loading of λQ onto the transcription elongation complex halted at a σ-dependent pause requiring a specific DNA element. The molecular basis of λQ-dependent AT and its dependence on N-utilization substance (Nus) A is so far only poorly understood. Here we used solution-state nuclear magnetic resonance spectroscopy to show that the solution structure of λQ is in agreement with the crystal structure of an N-terminally truncated variant and that the 60 residues at the N-terminus are unstructured. We also provide evidence that multidomain protein NusA interacts directly with λQ via its N-terminal domain (NTD) and the acidic repeat (AR) 2 domain, with the λQ:NusA-AR2 interaction being able to release NusA autoinhibition. The binding sites for NusA-NTD and NusA-AR2 on λQ overlap and the interactions are mutually exclusive with similar affinities, suggesting distinct roles during λQ-dependent AT, e.g. the λQ:NusA-NTD interaction might position NusA-NTD in a way to suppress termination, making NusA-NTD repositioning a general scheme in AT mechanisms.