Dynamics of Carbon Monoxide Binding to CooA

Puranik, Mrinalini; Nielsen, Steen Brøndsted; Youn, Hwan; Hvitved, Angela N.; Bourassa, James; Case, Martin A.; Tengroth, Charbel; Balakrishnan, Gurusamy; Thorsteinsson, Marc V.; Groves, John T.; McLendon, George; Roberts, Gary P.; Olson, John S.; Spiro, Thomas G.

doi:10.1074/jbc.m400613200

Cited by 63 publications

(89 citation statements)

References 27 publications

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“…These substitutions do not lie near the DNA-contacting surfaces and are best explained by their creating a shift in the equilibrium such that a larger fraction of the CooA population is truly active. Another line of evidence discussed below, is from kinetic analysis, which has shown that there are two different states of the heme in a population of CO-bound wild-type CooA, as revealed by substantially different CO off-rates (103). Lastly, the failure to obtain crystals of the CO-bound CooA is consistent with the hypothesis of the heterogeneity of this form.…”

Section: Population Dynamics Of the Cooa Response To Comentioning

confidence: 49%

CO-Sensing Mechanisms

Roberts

Youn

Kerby

2004

Microbiol Mol Biol Rev

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101

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Carbon monoxide (CO) has long been known to have dramatic physiological effects on organisms ranging from bacteria to humans, but recently there have a number of suggestions that organisms might have specific sensors for CO. This article reviews the current evidence for a variety of proteins with demonstrated or potential CO-sensing ability. Particular emphasis is placed on the molecular description of CooA, a heme-containing CO sensor from Rhodospirillum rubrum, since its biological role as a CO sensor is clear and we have substantial insight into the basis of its sensing ability

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Section: Population Dynamics Of the Cooa Response To Comentioning

confidence: 49%

CO-Sensing Mechanisms

Roberts

Youn

Kerby

2004

Microbiol Mol Biol Rev

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101

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“…Further discussion of this model for NO dissociation from sGC can be found in a previous report (29). Additionally, analogous models have been proposed to explain multiple exponentials observed for ligand binding to hexacoordinate globins (40) and to the CO sensor CooA (41).…”

Section: Resultsmentioning

confidence: 99%

Incorporation of Tyrosine and Glutamine Residues into the Soluble Guanylate Cyclase Heme Distal Pocket Alters NO and O2 Binding

Derbyshire

Deng

Marletta

2010

Journal of Biological Chemistry

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Nitric oxide (NO) is the physiologically relevant activator of the mammalian hemoprotein soluble guanylate cyclase (sGC).The heme cofactor of ␣1␤1 sGC has a high affinity for NO but has never been observed to form a complex with oxygen. Introduction of a key tyrosine residue in the sGC heme binding domain ␤1(1-385) is sufficient to produce an oxygen-binding protein, but this mutation in the full-length enzyme did not alter oxygen affinity. To evaluate ligand binding specificity in fulllength sGC we mutated several conserved distal heme pocket residues (␤1 Val-5, Phe-74, Ile-145, and Ile-149) to introduce a hydrogen bond donor in proximity to the heme ligand. We found that the NO coordination state, NO dissociation, and enzyme activation were significantly affected by the presence of a tyrosine in the distal heme pocket; however, the stability of the reduced porphyrin and the proteins affinity for oxygen were unaltered. Recently, an atypical sGC from Drosophila, Gyc-88E, was shown to form a stable complex with oxygen. Sequence analysis of this protein identified two residues in the predicted heme pocket (tyrosine and glutamine) that may function to stabilize oxygen binding in the atypical cyclase. The introduction of these residues into the rat ␤1 distal heme pocket (Ile-145 3 Tyr and Ile-149 3 Gln) resulted in an sGC construct that oxidized via an intermediate with an absorbance maximum at 417 nm. This absorbance maximum is consistent with globin Fe II -O 2 complexes and is likely the first observation of a Fe II -O 2 complex in the full-length ␣1␤1 protein. Additionally, these data suggest that atypical sGCs stabilize O 2 binding by a hydrogen bonding network involving tyrosine and glutamine.Soluble guanylate cyclase (sGC) 3 is the most thoroughly characterized receptor for the gaseous signaling agent nitric oxide (NO). NO induced activation of sGC is critical to several physiological processes, including neurotransmission, vasodilation, and platelet aggregation (1-3). The importance of sGC to physiological function has been clearly demonstrated over the last decade (4, 5); however, much less is understood about the molecular mechanisms that regulate enzyme activity.sGC is a heterodimeric hemoprotein consisting of two homologous subunits, ␣ and ␤. The ␣1␤1 heterodimer is the most prevalent and commonly studied protein. Despite the same histidine ligated heme and iron oxidation state as found in the globins, sGC shows no measurable affinity for O 2 and therefore can selectively bind NO in the presence of O 2 (reviewed in Refs. 6, 7). Interestingly, not only does sGC discriminate against O 2 binding to the heme, but both the Fe II -unligated and Fe II -NO species are stable in an aerobic environment (8). This is in stark contrast to other hemoproteins that readily bind and ultimately react with O 2 (9 -12). The mechanism by which sGC discriminates against O 2 binding as well as the molecular events that lead to activation remain to be elucidated.There have been several proposals on the mechanism of ligand discr...

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“…CooA regulates the pathway, binding CO to activate expression of genes for oxidation of CO to CO 2 and reduction of protons to H 2 (57). CooA is a homodimeric heme-binding cAMP receptor protein (CRP) transcriptional regulator family member that binds CO cooperatively (58). Inactive ferric CooA has a Cys-75 thiolate heme ligand, which switches to His-77 in ferrous CooA.…”

Section: Cooamentioning

confidence: 99%

Heme Sensor Proteins

Girvan

Munro

2013

Journal of Biological Chemistry

128

116

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Heme is a prosthetic group best known for roles in oxygen transport, oxidative catalysis, and respiratory electron transport. Recent years have seen the roles of heme extended to sensors of gases such as O 2 and NO and cell redox state, and as mediators of cellular responses to changes in intracellular levels of these gases. The importance of heme is further evident from identification of proteins that bind heme reversibly, using it as a signal, e.g. to regulate gene expression in circadian rhythm pathways and control heme synthesis itself. In this minireview, we explore the current knowledge of the diverse roles of heme sensor proteins. Heme-responsive Proteins: Defining FeaturesHeme homeostasis is crucial. Free heme at Ͼ1 M is cytotoxic, mainly by producing reactive oxygen species. Iron intake accounts for only a small proportion of mammalian requirements, so iron recycling (particularly from heme) is critical (1). Tight regulation of heme synthesis/breakdown is needed. Heme regulates its own fate and controls several other biological processes. Heme-responsive proteins elicit cellular responses by binding/debinding heme or via changes in heme ligation (e.g. by gases) or redox state. They can be divided into two classes: nuclear receptor (NR) 2 hemoproteins and heme sensors with no NR function. Each heme-responsive protein has a heme regulatory motif (HRM), usually containing a CP motif (2). The Cys residue of the CP motif is an axial heme ligand. No other residues are conserved across the protein class. The wider relevance of the CP motif is unclear because other hemoproteins (e.g. prostaglandin E 2 synthase, chloroperoxidase, and some cytochromes P450) also have a CP motif. The properties of members of the two main classes are described below. NR HemoproteinsSeveral heme-binding proteins occur in the NR superfamily, which is the largest transcription factor superfamily (summarized in Table 1). NRs bind specific DNA motifs in response to small molecule signaling. They generally share conserved domain architecture, with a DNA-binding region containing two zinc fingers, a ligand-binding domain, and activation domains (3). Usually, ligand binding induces conformational changes that dissociate partner proteins, allowing DNA binding and/or changes to dimerization status or cellular localization that enable the protein to elicit a response. A subfamily of NRs binds heme at their ligand-binding domain and so act as heme sensors, as discussed below. Circadian Rhythm Heme SensorsCircadian rhythms are regulated by feedback loops at transcriptional/translational levels. Heme is critical in this process (4). In vertebrates, the expression of several day/night cycle genes, as well as Rev-erb␣, is controlled by binding a heterodimer of Clock (or NPAS2 (neuronal PAS domain protein 2)) and Bmal1 to their 5Ј-UTR, thus switching on transcription. Expression of Bmal1 and NPAS2/Clock is repressed in turn by binding of Rev-erb␣ to a homodimeric partner (5). Rev-erb␣ and homologs (Rev-erb␤ and E75, with the latter involved in inse...

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Dynamics of Carbon Monoxide Binding to CooA

Cited by 63 publications

References 27 publications

CO-Sensing Mechanisms

CO-Sensing Mechanisms

Incorporation of Tyrosine and Glutamine Residues into the Soluble Guanylate Cyclase Heme Distal Pocket Alters NO and O2 Binding

Heme Sensor Proteins

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