The dormancy‐specific regulator, SutA, is intrinsically disordered and modulates transcription initiation in Pseudomonas aeruginosa. Issue 3 (10th July 2019)

• Record Type: Journal Article
• Authors: Bergkessel, Megan; Babin, Brett M.; VanderVelde, David; Sweredoski, Michael J.; Moradian, Annie; Eggleston‐Rangel, Roxana; Hess, Sonja; Tirrell, David A.; Artsimovitch, Irina; Newman, Dianne K.
• Is Part Of: Molecular microbiology. Volume 112:Issue 3(2019)
• Page Start: 992
• Page End: 1009
• Publication Date: 2019-07-10
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.14337
• Languages: English
• ISSNs: 0950-382X

Abstract

Summary: Though most bacteria in nature are nutritionally limited and grow slowly, our understanding of core processes like transcription comes largely from studies in model organisms doubling rapidly. We previously identified a small protein of unknown function, SutA, in a screen of proteins synthesized in Pseudomonas aeruginosa during dormancy. SutA binds RNA polymerase (RNAP), causing widespread changes in gene expression, including upregulation of the ribosomal RNA genes. Here, using biochemical and structural methods, we examine how SutA interacts with RNAP and the functional consequences of these interactions. We show that SutA comprises a central α‐helix with unstructured N‐ and C‐terminal tails, and binds to the β1 domain of RNAP. It activates transcription from the rrn promoter by both the housekeeping sigma factor holoenzyme (Eσ 70 ) and the stress sigma factor holoenzyme (Eσ S ) in vitro, but has a greater impact on Eσ S . In both cases, SutA appears to affect intermediates in the open complex formation and its N‐terminal tail is required for activation. The small magnitudes of in vitro effects are consistent with a role in maintaining activity required for homeostasis during dormancy. Our results add SutA to a growing list of transcription regulators that use their intrinsically disordered regions to remodel transcription complexes. Abstract : Mechanisms of bacterial transcription regulation that operate during slow growth and dormancy are not well understood, despite the fact that bacteria spend a lot of time in these states. We show here that a dormancy‐specific regulator of P. aeruginosa, SutA, is an intrinsically disordered protein that binds to the β1 domain of RNA polymerase and directly enhances initiation at the ribosomal RNA promoter, likely by affecting the conformation of an intermediate in open complex formation.