Regulation and Function of Cytochrome
            <i>c</i>
            ′ in
            <i>Rhodobacter sphaeroides</i>
            2.4.3

Choi, Peter S.; Grigoryants, Vladimir M.; Abruña, Héctor D.; Scholes, Charles P.; Shapleigh, James P.

doi:10.1128/jb.187.12.4077-4085.2005

Cited by 28 publications

(43 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They are typically homodimers with each monomer forming a four-α-helix bundle and containing a pentacoordinate (5c) c-type heme with a proximal histidine ligand and a vacant distal coordination site. Although the exact physiological functions of CYTcp remain unclear, previous studies have suggested roles in suppression of toxic levels of NO [3], defence against nitrosoative stress or an NO reductase activity [4], or NO shuttling between nitrite reductase and NO reductase during denitrification [5].…”

Section: Introductionmentioning

confidence: 99%

Conformational control of the binding of diatomic gases to cytochrome c′

et al. 2015

View full text Add to dashboard Cite

The cytochromes c' (CYTcp) are found in denitrifying, methanotrophic and photosynthetic bacteria. These proteins are able to form stable adducts with CO and NO but not with O2. The binding of NO to CYTcp currently provides the best structural model for the NO activation mechanism of soluble guanylate cyclase. Ligand binding in CYTcps has been shown to be highly dependent on residues in both the proximal and distal heme pockets. Group 1 CYTcps typically have a phenylalanine residue positioned close to the distal face of heme, while for group 2, this residue is typically leucine. We have structurally, spectroscopically and kinetically characterised the CYTcp from Shewanella frigidimarina (SFCP), a protein that has a distal phenylalanine residue and a lysine in the proximal pocket in place of the more common arginine. Each monomer of the SFCP dimer folds as a 4-alpha-helical bundle in a similar manner to CYTcps previously characterised. SFCP exhibits biphasic binding kinetics for both NO and CO as a result of the high level of steric hindrance from the aromatic side chain of residue Phe 16. The binding of distal ligands is thus controlled by the conformation of the phenylalanine ring. Only a proximal 5-coordinate NO adduct, confirmed by structural data, is observed with no detectable hexacoordinate distal NO adduct.

show abstract

Section: Introductionmentioning

confidence: 99%

Conformational control of the binding of diatomic gases to cytochrome c′

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The wild type RC strain was further shown to produce N 2 O when grown in the presence of NO, leading to the suggestion that RCCP is involved in reductase activity (8). Particularly since NO-reductase activity has not been demonstrated for purified RCCP or any other cytochrome cЈ, it is possible that cytochrome cЈ could be a transporter coupled to a NO reductase, as recently proposed for the species Chromatium vinosum (53) and Rhodobacter sphaeroides (54). In the context of a physiological NO binding role for AXCP, the overall picture is that the distal side controls the initial NO binding, whereas the proximal heme pocket controls the release of NO with the ability of trapping and gating NO despite its close proximity to solvent with a virtually unidirectional release of NO.…”

mentioning

confidence: 96%

Molecular Basis for Nitric Oxide Dynamics and Affinity with Alcaligenes xylosoxidans Cytochrome c´

Kruglik

Lambry

Cianetti

et al. 2007

Journal of Biological Chemistry

View full text Add to dashboard Cite

The bacterial heme protein cytochrome c from Alcaligenes xylosoxidans (AXCP) reacts with nitric oxide (NO) to form a 5-coordinate ferrous nitrosyl heme complex. The crystal structure of ferrous nitrosyl AXCP has previously revealed that NO is bound in an unprecedented manner on the proximal side of the heme. To understand how the protein structure of AXCP controls NO dynamics, we performed absorption and Raman timeresolved studies at the heme level as well as a molecular computational dynamics study at the entire protein structure level. We found that after NO dissociation from the heme iron, the structure of the proximal heme pocket of AXCP confines NO close to the iron so that an ultrafast (7 ps) and complete (99 ؎ 1%) geminate rebinding occurs, whereas the proximal histidine does not rebind to the heme iron on the timescale of NO geminate rebinding. The distal side controls the initial NO binding, whereas the proximal heme pocket controls its release. These dynamic properties allow the trapping of NO within the protein core and represent an extreme behavior observed among heme proteins.Nitric oxide (NO) acts as a second messenger in several physiological systems (1, 2), is involved in the production of several cytotoxic chemical species and nitrosative stress (3), and appears as an intermediate in the denitrification process (4). Cells have, thus, developed numerous heme proteins whose diverse functions involve nitric oxide binding and/or release. In some bacteria heme sensors were recently discovered (5) with a femtomolar affinity for NO, whereas cytochromes cЈ able to bind NO are found in many nitrogen-fixing, denitrifying, and photosynthetic bacteria (6). Although the physiological role the bacterial cytochrome cЈ from Alcaligenes xylosoxidans (AXCP) 2 is not yet established, the homologous cytochrome cЈ from Rhodobacter capsulatus has been shown to increase the resistance of this bacteria against NO toxicity (7,8). Thus, the bacterial cytochromes cЈ are inferred to disclose a particular behavior regarding NO dynamics and affinity. How heme proteins interact with NO and control its reactivity is ultimately related to their structure and the heme surroundings. A wide range of affinity and kinetic constants can be observed that correlates with the molecular dynamics of NO within the protein core. A striking example of this diversity is offered when comparing the NO dynamics governed by the enzyme NO synthase (9), the endogenous cellular source, and the NO receptorsoluble guanylate cyclase (10) (sGC) whose heme cofactor has a somewhat opposite role. Nitrosylated heme proteins usually form 6-coordinate complexes having histidine and NO as axial ligands at the proximal and distal sides of the heme, respectively (6c-NO-His), but some become 5-coordinate (5c) with NO (5c-NO) like sGC (11, 12) and AXCP (13,14). These latter proteins have an overall structure that presumably controls the strain upon the proximal histidine. Although sGC and AXCP possess different sequences and tertiary structures, they share the pro...

show abstract

“…Steric constraints and electrostatic interaction with the bound ligand on the distal side of the heme group can dramatically influence ligand selectivity (84,90). Different stereochemical strategies appear to have evolved to optimize both absolute ligand affinity and selectivity between NO, CO, and O 2 and to meet specific physiological needs for O 2 storage and transport [e.g., myoglobin (Mb), hemoglobin (Hb) (109)], O 2 sensing (e.g., FixL, EcDos, HemAT) (39), NO storage/transport (nitrophorins) (126), NO sensing (e.g., sGC, cyt c¢, and other sensors of NO) (15,22,26), and CO sensing (e.g., CooA and NPAS in circadian rhythm control) (8,29,95).…”

Section: Effect Of Protein On Heme Ligand Selectivitymentioning

confidence: 99%

How Do Heme-Protein Sensors Exclude Oxygen? Lessons Learned from Cytochrome c′,Nostoc puntiformeHeme Nitric Oxide/Oxygen-Binding Domain, and Soluble Guanylyl Cyclase

Tsai

Martin

Berka

et al. 2012

Antioxidants & Redox Signaling

View full text Add to dashboard Cite

Significance: Ligand selectivity for dioxygen (O 2 ), carbon monoxide (CO), and nitric oxide (NO) is critical for signal transduction and is tailored specifically for each heme-protein sensor. Key NO sensors, such as soluble guanylyl cyclase (sGC), specifically recognized low levels of NO and achieve a total O 2 exclusion. Several mechanisms have been proposed to explain the O 2 insensitivity, including lack of a hydrogen bond donor and negative electrostatic fields to selectively destabilize bound O 2 , distal steric hindrance of all bound ligands to the heme iron, and restriction of in-plane movements of the iron atom. Recent Advances: Crystallographic structures of the gas sensors, Thermoanaerobacter tengcongensis heme-nitric oxide/oxygen-binding domain (Tt H-NOX 1 ) or Nostoc puntiforme (Ns) H-NOX, and measurements of O 2 binding to site-specific mutants of Tt H-NOX and the truncated b subunit of sGC suggest the need for a H-bonding donor to facilitate O 2 binding. Critical Issues: However, the O 2 insensitivity of full length sGC with a site-specific replacement of isoleucine by a tyrosine on residue 145 and the very slow autooxidation of Ns H-NOX and cytochrome c¢ suggest that more complex mechanisms have evolved to exclude O 2 but retain high affinity NO binding. A combined graphical analysis of ligand binding data for libraries of heme sensors, globins, and model heme shows that the NO sensors dramatically inhibit the formation of six-coordinated NO, CO, and O 2 complexes by direct distal steric hindrance (cyt c¢), proximal constraints of in-plane iron movement (sGC), or combinations of both following a sliding scale rule. High affinity NO binding in H-NOX proteins is achieved by multiple NO binding steps that produce a high affinity five-coordinate NO complex, a mechanism that also prevents NO dioxygenation. Future Directions: Knowledge advanced by further extensive test of this ''sliding scale rule'' hypothesis should be valuable in guiding novel designs for heme based sensors.

show abstract

Regulation and Function of Cytochrome c ′ in Rhodobacter sphaeroides 2.4.3

Cited by 28 publications

References 48 publications

Conformational control of the binding of diatomic gases to cytochrome c′

Conformational control of the binding of diatomic gases to cytochrome c′

Molecular Basis for Nitric Oxide Dynamics and Affinity with Alcaligenes xylosoxidans Cytochrome c´

How Do Heme-Protein Sensors Exclude Oxygen? Lessons Learned from Cytochrome c′,Nostoc puntiformeHeme Nitric Oxide/Oxygen-Binding Domain, and Soluble Guanylyl Cyclase

Contact Info

Product

Resources

About