Article thumbnail

CorE from Myxococcus xanthus Is a Copper-Dependent RNA Polymerase Sigma Factor

By Nuria Gómez-Santos, Juana Pérez, María Celestina Sánchez-Sutil, Aurelio Moraleda-Muñoz and José Muñoz-Dorado

Abstract

The dual toxicity/essentiality of copper forces cells to maintain a tightly regulated homeostasis for this metal in all living organisms, from bacteria to humans. Consequently, many genes have previously been reported to participate in copper detoxification in bacteria. Myxococcus xanthus, a prokaryote, encodes many proteins involved in copper homeostasis that are differentially regulated by this metal. A σ factor of the ECF (extracytoplasmic function) family, CorE, has been found to regulate the expression of the multicopper oxidase cuoB, the P1B-type ATPases copA and copB, and a gene encoding a protein with a heavy-metal-associated domain. Characterization of CorE has revealed that it requires copper to bind DNA in vitro. Genes regulated by CorE exhibit a characteristic expression profile, with a peak at 2 h after copper addition. Expression rapidly decreases thereafter to basal levels, although the metal is still present in the medium, indicating that the activity of CorE is modulated by a process of activation and inactivation. The use of monovalent and divalent metals to mimic Cu(I) and Cu(II), respectively, and of additives that favor the formation of the two redox states of this metal, has revealed that CorE is activated by Cu(II) and inactivated by Cu(I). The activation/inactivation properties of CorE reside in a Cys-rich domain located at the C terminus of the protein. Point mutations at these residues have allowed the identification of several Cys involved in the activation and inactivation of CorE. Based on these data, along with comparative genomic studies, a new group of ECF σ factors is proposed, which not only clearly differs mechanistically from the other σ factors so far characterized, but also from other metal regulators

Topics: Research Article
Publisher: Public Library of Science
OAI identifier: oai:pubmedcentral.nih.gov:3107203
Provided by: PubMed Central

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.

Suggested articles

Citations

  1. (2007). A conserved structural module regulates transcriptional responses to diverse stress signals in bacteria.
  2. (2008). A place for thioether chemistry in cellular copper ion recognition and trafficking.
  3. (2010). Anatomy of a red copper center: spectroscopic identification and reactivity of the copper centers of Bacillus subtilis Sco and its Cys-to-Ala variants.
  4. (1999). AsgD, a new two-component regulator required for A-signalling and nutrient sensing during early development of Myxococcus xanthus.
  5. (2010). Bacterial metal sensing proteins exemplified by ArsRSmtB family repressors.
  6. (2008). Carotenogenesis in Myxococcus xanthus: a complex regulatory network. In:
  7. (2007). Clustal W and Clustal X version 2.0.
  8. (2008). Copper homeostasis in bacteria.
  9. (2007). Differential expression of the three multicopper oxidases from Myxococcus xanthus.
  10. (2008). Eukaryotic-like protein kinases in the prokaryotes and the myxobacterial kinome.
  11. (2000). Garza A
  12. (2009). How do bacterial cells ensure that metalloproteins get the correct metal?
  13. (2007). Identification of mycobacterial sigma factor binding sites by chromatin immunoprecipitation assays.
  14. (2007). Metal sensor proteins: nature’s metalloregulated allosteric switches.
  15. (2009). Metalloproteins and metal sensing.
  16. (2003). Molecular basis of metal-ion selectivity and zeptomolar sensitivity by CueR.
  17. (2001). Molecular cloning: a laboratory manual.
  18. (2008). Myxobacteria. Multicellularity and differentiation.
  19. (2002). Nanotransducers in cellular redox signaling: modification of thiols by reactive oxygen and nitrogen species.
  20. (2005). o zA ,P e ´rez
  21. (2010). o zA ,P e ´rez J, Extremera-Leo ´n AL, Mun ˜oz-Dorado J
  22. (2010). Orchestrating redox signaling networks through regulatory cysteine switches.
  23. (2001). Periplasmic stress and ECF sigma factors.
  24. (2010). Response of Gram-positive bacteria to copper stress.
  25. (2008). Signaling mechanisms for activation of extracytoplasmic function (ECF) sigma factors.
  26. (2007). Stress responses of bacteria.
  27. (2005). Structural determinants of metal selectivity in prokaryotic metal-responsive transcriptional regulators.
  28. (2002). Structure of the bacterial RNA polymerase promoter specificity sigma subunit.
  29. (2010). Tetrathiomolybdate inhibits copper trafficking proteins through metal cluster formation.
  30. (1998). The anti-sigma factors.
  31. (2011). The essential role of the Cu(II) state of Sco in the maturation of the CuA center of cytochrome oxidase: evidence from H135Met and H135SeM variants of the Bacillus subtilis Sco.
  32. (2002). The extracytoplasmic function (ECF) sigma factors.
  33. (2010). The Pfam protein families database.
  34. (2009). The third pillar of bacterial signal transduction: classification of the extracytoplasmic function (ECF) sigma factor protein family.
  35. (2008). Transfer of copper between bis(thiosemicarbazone) ligands and intracellular copper-binding proteins. Insights into mechanisms of copper uptake and hypoxia selectivity.
  36. (2011). Unification of the copper(I) binding affinities of the metallo-chaperones Atx1, Atox1 and related proteins: detection probes and affinity standards.
  37. (2005). Virtual Footprint and PRODORIC: an integrative framework for regulon prediction in prokaryotes.
  38. (2004). WebLogo: A sequence logo generator.