Structural and functional characterizations of SsgB, a conserved activator of developmental cell division in morphologically complex actinomycetes

Qingping Xu, Bjørn A. Traag, Joost Willemse, Daniel McMullan, Mitchell D. Miller, Marc André Elsliger, Polat Abdubek, Tamara Astakhova, Herbert L. Axelrod, Constantina Bakolitsa, Dennis Carlton, Connie Chen, Hsiu Ju Chiu, Maksymilian Chruszcz, Thomas Clayton, Debanu Das, Marc C. Deller, Lian Duan, Kyle Ellrott, Dustin ErnstCarol L. Farr, Julie Feuerhelm, Joanna C. Grant, Anna Grzechnik, Slawomir K. Grzechnik, Gye Won Ha, Lukasz Jaroszewski, Kevin K. Jin, Heath E. Klock, Mark W. Knuth, Piotr Kozbial, S. Sri Krishna, Abhinav Kumar, David Marciano, Wladek Minor, A. Mieke Mommaas, Andrew T. Morse, Edward Nigoghossian, Amanda Nopakun, Linda Okach, Silvya Oommachen, Jessica Paulsen, Christina Puckett, Ron Reyes, Christopher L. Rife, Natasha Sefcovic, Henry J. Tien, Christine B. Trame, Henry van den Bedem, Shuren Wang, Dana Weekes, Keith O. Hodgson, John Wooley, Ashley M. Deacon, Adam Godzik, Scott A. Lesley, Ian A. Wilson, Gilles P. van Wezel

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


SsgA-like proteins (SALPs) are a family of homologous cell division-related proteins that occur exclusively in morphologically complex actinomycetes. We show that SsgB, a subfamily of SALPs, is the archetypal SALP that is functionally conserved in all sporulating actinomycetes. Sporulation-specific cell division of Streptomyces coelicolor ssgB mutants is restored by introduction of distant ssgB orthologues from other actinomycetes. Interestingly, the number of septa (and spores) of the complemented null mutants is dictated by the specific ssgB orthologue that is expressed. The crystal structure of the SsgB from Thermobifida fusca was determined at 2.6 Å resolution and represents the first structure for this family. The structure revealed similarities to a class of eukaryotic "whirly" single-stranded DNA/RNA-binding proteins. However, the electro-negative surface of the SALPs suggests that neither SsgB nor any of the other SALPs are likely to interact with nucleotide substrates. Instead, we show that a conserved hydrophobic surface is likely to be important for SALP function and suggest that proteins are the likely binding partners.

Original languageEnglish (US)
Pages (from-to)25268-25279
Number of pages12
JournalJournal of Biological Chemistry
Issue number37
StatePublished - Sep 11 2009
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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