The dormancy-specific regulator, SutA, is intrinsically disordered and modulates transcription initiation in Pseudomonas aeruginosa

Mol Microbiol. 2019 Sep;112(3):992-1009. doi: 10.1111/mmi.14337. Epub 2019 Jul 10.

Abstract

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 (Eσ70 ) and the stress sigma factor holoenzyme (EσS ) in vitro, but has a greater impact on EσS . 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Proteins / metabolism*
  • DNA-Directed RNA Polymerases / genetics
  • DNA-Directed RNA Polymerases / metabolism
  • Gene Expression Regulation, Bacterial*
  • Promoter Regions, Genetic
  • Pseudomonas aeruginosa / genetics
  • Pseudomonas aeruginosa / growth & development*
  • Pseudomonas aeruginosa / metabolism
  • Sigma Factor / genetics
  • Sigma Factor / metabolism
  • Transcription, Genetic*
  • Transcriptional Activation

Substances

  • Bacterial Proteins
  • Sigma Factor
  • DNA-Directed RNA Polymerases