The crystal structure of the RsbN-σBldN complex from Streptomyces venezuelae defines a new structural class of anti-σ factor.

Published

Journal Article

Streptomyces are filamentous bacteria with a complex developmental life cycle characterized by the formation of spore-forming aerial hyphae. Transcription of the chaplin and rodlin genes, which are essential for aerial hyphae production, is directed by the extracytoplasmic function (ECF) σ factor BldN, which is in turn controlled by an anti-σ factor, RsbN. RsbN shows no sequence similarity to known anti-σ factors and binds and inhibits BldN in an unknown manner. Here we describe the 2.23 Å structure of the RsbN-BldN complex. The structure shows that BldN harbors σ2 and σ4 domains that are individually similar to other ECF σ domains, which bind -10 and -35 promoter regions, respectively. The anti-σ RsbN consists of three helices, with α3 forming a long helix embraced between BldN σ2 and σ4 while RsbN α1-α2 dock against σ4 in a manner that would block -35 DNA binding. RsbN binding also freezes BldN in a conformation inactive for simultaneous -10 and -35 promoter interaction and RNAP binding. Strikingly, RsbN is structurally distinct from previously solved anti-σ proteins. Thus, these data characterize the molecular determinants controlling a central Streptomyces developmental switch and reveal RsbN to be the founding member of a new structural class of anti-σ factor.

Full Text

Duke Authors

Cited Authors

  • Schumacher, MA; Bush, MJ; Bibb, MJ; Ramos-León, F; Chandra, G; Zeng, W; Buttner, MJ

Published Date

  • August 21, 2018

Published In

Volume / Issue

  • 46 / 14

Start / End Page

  • 7405 - 7417

PubMed ID

  • 29905823

Pubmed Central ID

  • 29905823

Electronic International Standard Serial Number (EISSN)

  • 1362-4962

Digital Object Identifier (DOI)

  • 10.1093/nar/gky493

Language

  • eng

Conference Location

  • England