A Role for the Conserved GAFTGA Motif of AAA+ Transcription Activators in Sensing Promoter DNA Conformation*

  1. Angel Ernesto Dago ‡ 1 2 ,
  2. Siva R. Wigneshweraraj § 1 ,
  3. Martin Buck § 3 and
  4. Enrique Morett ‡ 4
  1. ‡Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos 62210, México and the §Division of Biology, Faculty of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
  1. 3 To whom correspondence may be addressed: Division of Biology, Faculty of Life Sciences, Sir Alexander Fleming Bldg., Imperial College London, London SW7 2AZ, UK. Tel.: 44-207-594-5419; Fax: 44-207-594-5366; E-mail: m.buck{at}imperial.ac.uk. 4 To whom correspondence may be addressed: Dept. de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, AP 510-3, Cuernavaca, Morelos 62210, México. Tel.: 52-777-3291665; Fax: 52-777-3172388; E-mail: emorett{at}ibt.unam.mx.

Abstract

Transcription from σ54-dependent bacterial promoters can be regarded as a second paradigm for bacterial gene transcription. The initial σ54-RNA polymerase (RNAP)·promoter complex, the closed complex, is transcriptionally silent. The transcriptionally proficient σ54-RNAP·promoter complex, the open complex, is formed upon remodeling of the closed complex by actions of a specialized activator protein that belongs to the AAA (ATPases associated with various cellular activities) protein family in an ATP hydrolysis-dependent reaction. The integrity of a highly conserved signature motif in the AAA activator (known as the GAFTGA motif) is important for the remodeling activity of the AAA activator and for open complex formation. We now provide evidence that the invariant threo-nine residue of the GAFTGA motif plays a role in sensing the DNA downstream of the σ54-RNAP-binding site and in coupling this information to σ54-RNAP via the conserved regulatory Region I domain of σ54 during open complex formation.

Footnotes

  • ↵5 The abbreviations used are: RNAP, RNA polymerase; L1, loop 1; X-gal, 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside.

  • ↵6 P. C. Burrows, S. R. Wigneshweraraj, and M. Buck, unpublished data.

  • ↵* This work was supported in part by the Biotechnology and Biological Sciences Research Council (to M. B.) and the Dirección General de Asuntos del Personal Académico (DGAPA) (to E. M.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

  • ↵1 Both authors contributed equally to this work.

  • ↵2 Recipient of a scholarship from the Dirección General de Estudios de Posgrado, Universidad Nacional Autónoma de México.

    • Received September 11, 2006.
    • Revision received October 25, 2006.
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  1. First Published on November 6, 2006 doi: 10.1074/jbc.M608715200 The Journal of Biological Chemistry 282, 1087-1097.
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