Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Influence of Polar Mutations on the Electronic and Structural Properties of QA–· in Bacterial Reaction Centers

Technical Report ·
DOI:https://doi.org/10.2172/2234289· OSTI ID:2234289
 [1];  [2];  [2]
  1. University of Illinois at Urbana-Champaign, IL (United States); RubrYc Therapeutics, San Carlos, CA (United States)
  2. University of Illinois at Urbana-Champaign, IL (United States)
+ Show Author Affiliations

Reaction centers from Rb. sphaeroides with residue M265 mutated from isoleucine to threonine, serine, and asparagine (M265IT, M265IS, and M265IN, respectively) in the QA–· state are studied by high-resolution ESEEM and ENDOR spectroscopies to investigate the structural characteristics of these mutants influencing the redox properties of the QA site. All three mutants decrease the redox midpoint potential (Em) of QA by ~0.1 V, yet the mechanism for this drop in Em is unclear. In this work, we examine (i) the hydrogen bonding interactions between QA–· and residues histidine M219 and alanine M260, (ii) the electron spin density distribution of the semiquinone, and (iii) the orientations of the ubiquinone methoxy substituents. 13C measurements show no significant contribution of methoxy dihedral angles to the observed decrease in Em for the QA mutants. Instead, 14N three-pulse ESEEM data suggest electrostatic or hydrogen bond formation between the mutated M265 side chain and His-M219 Nδ may be involved in the observed lowering of the QA midpoint potential. For mutant M265IN, analysis of the proton hyperfine couplings reveals a weakened hydrogen bond network, resulting in an altered QA–· spin density distribution. Here, the magnetic resonance study presented here is therefore most consistent with an electrostatic or structural perturbation of the His-M219 Nδ hydrogen bond in these mutants as a mechanism for the ~0.1 V decrease in QA Em.

Research Organization:
Univ. of Illinois at Urbana-Champaign, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB); National Science Foundation (NSF); NCRR/NIH
DOE Contract Number:
FG02-08ER15960; MCB-0818121; S10-RR15878; S10-RR025438
OSTI ID:
2234289
Report Number(s):
DOE-UICU-15960
Country of Publication:
United States
Language:
English

References (40)

The interaction of quinone and detergent with reaction centers of purple bacteria. I. Slow quinone exchange between reaction center micelles and pure detergent micelles journal May 1997
Evidence that Ala M260 is hydrogen-bonded to the reduced primary acceptor quinone QA−. in reaction centers of Rb. sphaeroides journal December 1996
Tuning Cofactor Redox Potentials: The 2-Methoxy Dihedral Angle Generates a Redox Potential Difference of >160 mV between the Primary (Q A ) and Secondary (Q B ) Quinones of the Bacterial Photosynthetic Reaction Center journal October 2013
Proton and electron transfer in the acceptor quinone complex of photosynthetic reaction centers from Rhodobacter Sphaeroides journal January 2004
A quantum chemical investigation of structures, vibrational spectra and electron affinities of the radicals of quinone model compounds journal March 1998
Intensity of Cross-Peaks in Hyscore Spectra of S = 1/2, I = 1/2 Spin Systems journal June 2000
Hydrogen Bonding and Spin Density Distribution in the Q B Semiquinone of Bacterial Reaction Centers and Comparison with the Q A Site journal April 2011
Parameters of quadrupole coupling of 14N nuclei in chlorophyll a cations determined by the electron spin echo method journal July 1982
Primary Quinone (QA) Binding Site of Bacterial Photosynthetic Reaction Centers:  Mutations at Residue M265 Probed by FTIR Spectroscopy journal March 2003
Nuclear quadrupole interactions in copper(II)-diethylenetriamine-substituted imidazole complexes and in copper(II) proteins journal December 1990
Pulsed ENDOR at 95 GHz on the Primary Acceptor Ubisemiquinone in Photosynthetic Bacterial Reaction Centers and Related Model Systems journal May 1998
Coupling of electron transfer to proton uptake at the QB site of the bacterial reaction center: A perspective from FTIR difference spectroscopy journal October 2008
Nuclear Hyperfine and Quadrupole Tensor Characterization of the Nitrogen Hydrogen Bond Donors to the Semiquinone of the Q B Site in Bacterial Reaction Centers: A Combined X- and S-Band 14,15 N ESEEM and DFT Study journal January 2014
Electron transfer in reaction centers of Rhodopseudomonas sphaeroides. I. Determination of the charge recombination pathway of D+QAQ−B and free energy and kinetic relations between Q−AQB and QAQ−B journal July 1984
General and efficient simulation of pulse EPR spectra journal January 2009
Determination of Electronic Structure of Molecules from Nuclear Quadrupole Effects journal September 1949
Influence of Hyperfine Coupling Strain on Two-Dimensional ESEEM Spectra from I = 1/2 Nuclei journal August 2020
Hyperfine and Nuclear Quadrupole Tensors of Nitrogen Donors in the Q A Site of Bacterial Reaction Centers: Correlation of the Histidine N δ Tensors with Hydrogen Bond Strength journal July 2014
Electron acceptors of bacterial photosynthetic reaction centers II. H+ binding coupled to secondary electron transfer in the quinone acceptor complex journal November 1979
Direct Evidence for Nitrogen Ligation to the High Stability Semiquinone Intermediate in Escherichia coli Nitrate Reductase A journal January 2010
Cross-Peak Lineshape of Two-Dimensional ESEEM Spectra in Disordered S = 12, I = 12 Spin Systems journal September 1995
The primary and secondary acceptors in bacterial photosynthesis III. Characterization of the quinone radicals Q A − ⋅ and Q B − ⋅ by EPR and ENDOR journal May 1999
The effect of methoxy group rotation and hydrogen bonding on the redox properties of ubiquinone journal October 2015
High-field EPR, ENDOR and ELDOR on bacterial photosynthetic reaction centers journal March 2007
Modulation of the free energy of the primary quinone acceptor (QA) in reaction centers from Rhodobacter sphaeroides: contributions from the protein and protein–lipid(cardiolipin) interactions journal April 2004
Protein-Cofactor Interactions in Bacterial Reaction Centers from Rhodobacter sphaeroides R-26: II. Geometry of the Hydrogen Bonds to the Primary Quinone QA⋅⁡− by 1H and 2H ENDOR Spectroscopy journal January 2007
Conformational Differences between the Methoxy Groups of Q A and Q B Site Ubisemiquinones in Bacterial Reaction Centers: A Key Role for Methoxy Group Orientation in Modulating Ubiquinone Redox Potential journal June 2013
Hydrogen Bonds between Nitrogen Donors and the Semiquinone in the Q B Site of Bacterial Reaction Centers journal August 2010
Kinetics and thermodynamics of the P870+Q−A → P870+Q−B reaction in isolated reaction centers from the photosynthetic bacterium Rhodopseudomonas sphaeroides journal January 1984
Systematic High-Accuracy Prediction of Electron Affinities for Biological Quinones: Systematic High-Accuracy Prediction of Electron Affinities for Biological Quinones journal October 2018
The 2-Methoxy Group Orientation Regulates the Redox Potential Difference between the Primary (QA) and Secondary (QB) Quinones of Type II Bacterial Photosynthetic Reaction Centers journal July 2014
1D- and 2D-ESEEM Study of the Semiquinone Radical Q A - of Photosystem II journal August 1999
Electron Paramagnetic Resonance Studies of Zinc-Substituted Reaction Centers from Rhodopseudomonas viridis journal August 1999
Protein-Cofactor Interactions in Bacterial Reaction Centers from Rhodobacter sphaeroides R-26: I. Identification of the ENDOR Lines Associated with the Hydrogen Bonds to the Primary Quinone QA⋅− journal May 2006
Protein Control of the Redox Potential of the Primary Quinone Acceptor in Reaction Centers from Rhodobacter sphaeroides journal January 2001
Interplay of substituent conformation and electron affinity in quinone models of quinone reductases journal June 1990
The involvement of iron and ubiquinone in electron transfer reactions mediated by reaction centers from photosynthetic bacteria journal March 1979
Two-Dimensional Pulsed EPR Resolves Hyperfine Coupling Strain in Nitrogen Hydrogen Bond Donors of Semiquinone Intermediates journal April 2018
The primary acceptor quinone QA in reaction centers of Rhodobacter sphaeroides R26 is hydrogen bonded to the Nσ(1)-H of His M219. An electron spin echo study of QA−• journal June 1995
A comparative electron spin echo envelope modulation study of the primary electron acceptor quinone in Zn-substituted and cyanide-treated preparations of photosystem II journal June 1998

Similar Records

How Can a Single Second Sphere Amino Acid Substitution Cause Reduction Midpoint Potential Changes of Hundreds of Millivolts?
Journal Article · 2009 · J. Am. Chem. Soc. 129:9927,2007 · OSTI ID:953911
+5 more
The Raised Midpoint Potential of the[2Fe2S] Cluster of Cytochrome bc1 is Mediated by Both the Q(o) Site Occupants and the Head Domain Position of the Fe-S Protein Subunit
Journal Article · 2004 · Biochemistry (Eaton) · OSTI ID:15007033
+2 more
Q-Band Electron-Nuclear Double Resonance Reveals Out-of-Plane Hydrogen Bonds Stabilize an Anionic Ubisemiquinone in Cytochrome bo3 from Escherichia coli [Q-Band ENDOR Reveals Out-of-Plane Hydrogen Bonds Stabilize an Anionic Ubisemiquinone in Cytochrome bo3 from Escherichia coli]
Journal Article · 2016 · Biochemistry · OSTI ID:1465174
+5 more

Related Subjects

14 SOLAR ENERGY
Reaction centers from Rb. sphaeroides
residue M265 mutated from isoleucine to threonine
serine
and asparagine (M265IT, M265IS, and M265IN, respectively) in the QA‒• state
high-resolution ESEEM and ENDOR spectroscopies
electrostatic or hydrogen bond formation between the mutated M265 side chain and His-M219 Nδ
energy levels
magnetic properties
nitrogen
noncovalent interactions
quinones