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The dormancy‐specific regulator, SutA, is intrinsically disordered and modulates transcription initiation in Pseudomonas aeruginosa
Author(s) -
Bergkessel Megan,
Babin Brett M.,
VanderVelde David,
Sweredoski Michael J.,
Moradian Annie,
EgglestonRangel Roxana,
Hess Sonja,
Tirrell David A.,
Artsimovitch Irina,
Newman Dianne K.
Publication year - 2019
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14337
Subject(s) - biology , sigma factor , rna polymerase , transcription (linguistics) , microbiology and biotechnology , transcription factor , rna polymerase ii , bacterial transcription , stringent response , promoter , genetics , gene , rna , gene expression , mutant , linguistics , philosophy
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.