DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state.

DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Research Abstract Details 

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DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Abstract Text:

Robert W Clark,Hwan Youn,Andrea J Lee,Gary P Roberts,Judith N Burstyn,

CooA is a transcription factor from Rhodospirillum rubrum that is regulated by the binding of the small molecule effector, CO, to a heme moiety in the protein. The heme in CooA is axially ligated by two endogenous donors in the Fe(III) and Fe(II) states of the protein, and CO binding to the Fe(II) state results in replacement of the distal ligand. Reduction of the heme in the absence of CO results in a ligand switch on the proximal side, in which a cysteine thiolate in the Fe(III) state is replaced by a histidine in the Fe(II) state. Recently, a variant, termed RW CooA, was designed to respond to a new effector; Fe(II) RW CooA shows high specificity and induced DNA-binding activity in the presence of imidazole. Spectroscopic characterization of the imidazole adducts of RW CooA revealed that, unlike CO, imidazole binds to both Fe(III) RW CooA and Fe(II) RW CooA. The spectral characteristics are consistent with normal function of the redox-mediated ligand switch; Fe(III)-imidazole RW CooA bears a thiolate ligand and Fe(II)-imidazole RW CooA bears a neutral donor ligand. Since the effector binds to both redox states, RW CooA was used to probe the role of the redox-mediated ligand switch in the CooA activation mechanism. Functional studies of Fe(III)-imidazole and Fe(II)-imidazole ligated RW CooA demonstrate that only the Fe(II)-imidazole form is active for DNA binding. Thus, the ligand switch is essential for the activating conformational change and may prevent aberrant activation of CooA by other neutral diatomic molecules.

DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Publishing Authors By Initials

RW Clark,H Youn,AJ Lee,GP Roberts,JN Burstyn,

For similar proteins: dna-binding proteins: trans-activators research abstracts see: proteins: dna-binding proteins: trans-activators research

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DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Journal Published:

PUBLICATION TYPE: Research Support, N.I.H., Extr

Journal: Journal of biological inorganic chemistry : JBIC :

VOLUME: 12

Page Numbers: 139-46

Journal Abbreviation: J. Biol. Inorg. Chem.

ISSN: 0949-8257

DAY: 3

MONTH: 11

YEAR: 2006

DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 9616326

DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Keywords Mesh Terms:

KEYWORDS: Trans-Activators

MESH TERMS: metabolism

Chemical & Substance for Abstract: DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state. Information

Substance Name: Histidine

Registry Number: 71-00-1

Grant and Affiliation Information for DNA binding by an imidazole-sensing CooA variant is dependent on the heme redox state.

AFFILIATION: Department of Chemistry, Hope College, Holland, MI 49423, USA.

Country: Germany

AGENCY: United States NHLBI

GRANT: HL-66147

ACRONYM: HL

MEDLINETA: J Biol Inorg Chem

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