HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 278, Issue 37, 35384-35393, September 12, 2003

This Article Full Text Full Text (PDF) All Versions of this Article: 278/37/35384    most recent M301000200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Coyle, C. M. Articles by Spiro, T. G. Search for Related Content PubMed PubMed Citation Articles by Coyle, C. M. Articles by Spiro, T. G. Social Bookmarking                      What's this?

Activation Mechanism of the CO Sensor CooA

MUTATIONAL AND RESONANCE RAMAN SPECTROSCOPIC STUDIES^*

Candace M. Coyle  , Mrinalini Puranik , Hwan Youn ¶, Steen Brøndsted Nielsen  ||, Robert D. Williams , Robert L. Kerby ¶, Gary P. Roberts ¶ and Thomas G. Spiro  **

From the Department of Chemistry, Princeton University, Princeton, New Jersey 08544 and ^¶Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706

CooA is a CO-dependent heme protein transcription factor of the bacterium Rhodospirillum rubrum. CO binding to its heme causes CooA to bind DNA and activate expression of genes for CO metabolism. To understand the nature of CO activation, several CooA mutational variants have been studied by resonance Raman spectroscopy, in vivo activity measurements, and DNA binding assays. Analysis of the Fe–C and C–O stretching Raman spectroscopy bands permits the conclusion that when CO displaces the Pro² heme ligand, the protein forms a hydrophobic pocket in which the C-helix residues Gly¹¹⁷, Leu¹¹⁶, and Ile¹¹³ are close to the bound CO. The displaced Pro² terminus is expelled from this pocket, unless the pH is raised above the pK_a, in which case the terminus remains in H-bond contact. The pK_a for this transition is 8.6, two units below that of aqueous proline, reflecting the hydrophobic nature of the pocket. The proximal Fe–His bond in Fe[II]CooA is as strong as it is in myoglobin but is weakened by CO binding, an effect attributable to loss of an H-bond from the proximal His⁷⁷ ligand to the adjacent Asn⁴² side chain. A structural model is proposed for the position of the CO-bound heme in the active form of CooA, which has implications for the mechanism of CO activation.

Received for publication, January 29, 2003 , and in revised form, May 16, 2003.

^* This work was supported in part by National Institutes of Health Grants GM 33576 (to T. G. S.) and GM 53228 (to G. P. R.) and by a postdoctoral fellowship (Grant 21-01-0142) from the Danish Natural Science Research Council (to S. B. N.). 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.

Present address: Dept. of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249.

^|| Present address: Dept. of Physics and Astronomy, University of Aarhus, Ny Munkegade, DK-8000 Aarhus C, Denmark.

^** To whom correspondence should be addressed. Tel.: 609-258-3907; Fax: 609-258-0348; E-mail: spiro{at}princeton.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Ibrahim, R. L. Kerby, M. Puranik, I. H. Wasbotten, H. Youn, G. P. Roberts, and T. G. Spiro Heme Displacement Mechanism of CooA Activation: MUTATIONAL AND RAMAN SPECTROSCOPIC EVIDENCE J. Biol. Chem., September 29, 2006; 281(39): 29165 - 29173. [Abstract] [Full Text] [PDF]

				M. Kubo, S. Inagaki, S. Yoshioka, T. Uchida, Y. Mizutani, S. Aono, and T. Kitagawa Evidence for Displacements of the C-helix by CO Ligation and DNA Binding to CooA Revealed by UV Resonance Raman Spectroscopy J. Biol. Chem., April 21, 2006; 281(16): 11271 - 11278. [Abstract] [Full Text] [PDF]

				R. W. Clark, N. D. Lanz, A. J. Lee, R. L. Kerby, G. P. Roberts, and J. N. Burstyn Unexpected NO-dependent DNA binding by the CooA homolog from Carboxydothermus hydrogenoformans PNAS, January 24, 2006; 103(4): 891 - 896. [Abstract] [Full Text] [PDF]

				T. Yamashita, Y. Hoashi, Y. Tomisugi, Y. Ishikawa, and T. Uno The C-helix in CooA Rolls upon CO Binding to Ferrous Heme J. Biol. Chem., November 5, 2004; 279(45): 47320 - 47325. [Abstract] [Full Text] [PDF]

				H. Youn, R. L. Kerby, and G. P. Roberts Changing the Ligand Specificity of CooA, a Highly Specific Heme-based CO Sensor J. Biol. Chem., October 29, 2004; 279(44): 45744 - 45752. [Abstract] [Full Text] [PDF]

				G. P. Roberts, H. Youn, and R. L. Kerby CO-Sensing Mechanisms Microbiol. Mol. Biol. Rev., September 1, 2004; 68(3): 453 - 473. [Abstract] [Full Text] [PDF]

				M. Puranik, S. B. Nielsen, H. Youn, A. N. Hvitved, J. L. Bourassa, M. A. Case, C. Tengroth, G. Balakrishnan, M. V. Thorsteinsson, J. T. Groves, et al. Dynamics of Carbon Monoxide Binding to CooA J. Biol. Chem., May 14, 2004; 279(20): 21096 - 21108. [Abstract] [Full Text] [PDF]

				T. Yamashita, Y. Hoashi, K. Watanabe, Y. Tomisugi, Y. Ishikawa, and T. Uno Roles of Heme Axial Ligands in the Regulation of CO Binding to CooA J. Biol. Chem., May 14, 2004; 279(20): 21394 - 21400. [Abstract] [Full Text] [PDF]

				J. Igarashi, A. Sato, T. Kitagawa, T. Yoshimura, S. Yamauchi, I. Sagami, and T. Shimizu Activation of Heme-regulated Eukaryotic Initiation Factor 2{alpha} Kinase by Nitric Oxide Is Induced by the Formation of a Five-coordinate NO-Heme Complex: OPTICAL ABSORPTION, ELECTRON SPIN RESONANCE, AND RESONANCE RAMAN SPECTRAL STUDIES J. Biol. Chem., April 16, 2004; 279(16): 15752 - 15762. [Abstract] [Full Text] [PDF]

				H. Youn, R. L. Kerby, M. Conrad, and G. P. Roberts Functionally Critical Elements of CooA-Related CO Sensors J. Bacteriol., March 1, 2004; 186(5): 1320 - 1329. [Abstract] [Full Text] [PDF]