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J. Biol. Chem., Vol. 277, Issue 9, 7282-7286, March 1, 2002
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Factor Used by RNA Polymerase to Stimulate Transcription
from Its Cognate Promoter*
and
From the Department of Biochemistry and Molecular and Cellular
Biology of Plants, Estación Experimental del Zaidín,
Consejo Superior de Investigaciones Científicas, Apartado de
Correos 419, E-18008 Granada, Spain
The 321-residue XylS and XylS1 proteins, encoded
by the pWW0 and pWW53 plasmids respectively, differ in only 5 residues
at positions 4, 53, 90, 137, and 153. As a result, the effector profile of XylS is wider than that of XylS1, and XylS mediates higher levels of
transcription from its cognate-regulatable promoter than does XylS1. We
generated a series of XylS-pWW0 mutants and found that the single
mutants Asp-137 
Glu and His-153 Asn exhibited an activation
pattern different from that of the wild-type regulator. In the
double-mutant XylSD137E,H153N the effector profile for benzoates was
similar to that of XylS1. This suggests that these two residues are
crucial for effector recognition and regulator activation to stimulate
transcription. XylS-dependent transcription from its
cognate promoter is mediated by RNA polymerase with
32 or 38, whereas XylS1 uses RNA
polymerase with 32 or 70. We also found
that point mutations at positions 137 and 153 of XylS led RNA
polymerase to mediate transcription with 70 rather than
with 38, as demonstrated by primer extension analysis in
a 70-thermosensitive background proficient and deficient
in 38. This suggests that a positive transcriptional
regulator can choose the RNA polymerase complex that mediates
transcription from a given promoter.
Recipient of a fellowship from the Spanish Ministry of Education
and Culture.
§
To whom correspondence should be addressed. Tel: 34-958-121011;
Fax: 34-958-129600; E-mail: jlramos@eez.csic.es.
This article has been cited by other articles:
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  P. Dominguez-Cuevas, P. Marin, S. Busby, J. L. Ramos, and S. Marques Roles of Effectors in XylS-Dependent Transcription Activation: Intramolecular Domain Derepression and DNA Binding J. Bacteriol., May 1, 2008; 190(9): 3118 - 3128. [Abstract] [Full Text] [PDF]
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 P. Dominguez-Cuevas, P. Marin, J. L. Ramos, and S. Marques RNA Polymerase Holoenzymes Can Share a Single Transcription Start Site for the Pm Promoter: CRITICAL NUCLEOTIDES IN THE -7 TO-18 REGION ARE NEEDED TO SELECT BETWEEN RNA POLYMERASE WITH {sigma}38 OR {sigma}32 J. Biol. Chem., December 16, 2005; 280(50): 41315 - 41323. [Abstract] [Full Text] [PDF]
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 D. Tropel and J. R. van der Meer Bacterial Transcriptional Regulators for Degradation Pathways of Aromatic Compounds Microbiol. Mol. Biol. Rev., September 1, 2004; 68(3): 474 - 500. [Abstract] [Full Text] [PDF]
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D. J. Lessner, R. E. Parales, S. Narayan, and D. T. Gibson Expression of the Nitroarene Dioxygenase Genes in Comamonas sp. Strain JS765 and Acidovorax sp. Strain JS42 Is Induced by Multiple Aromatic Compounds J. Bacteriol., July 1, 2003; 185(13): 3895 - 3904. [Abstract] [Full Text] [PDF]
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R. Ruiz, S. Marques, and J. L. Ramos Leucines 193 and 194 at the N-Terminal Domain of the XylS Protein, the Positive Transcriptional Regulator of the TOL meta-Cleavage Pathway, Are Involved in Dimerization J. Bacteriol., May 15, 2003; 185(10): 3036 - 3041. [Abstract] [Full Text] [PDF]
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