On the structure and function of cytochrome b-559

Cramer, William A.; Theg, Steven M.; Widger, William R.

doi:10.1007/bf00118305

Cited by 120 publications

(56 citation statements)

References 48 publications

(52 reference statements)

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“…[21]). Nevertheless, an accumulation of circumstancial evidence suggests a close association of cytochrome b-559 with the oxidizing side of photosystem I1 [l, 5,131, and Cramer et al [7] have very recently proposed a role for this elusive cytochrome as a mediator in the (re)assembly of the watersplitting enzyme in chloroplast development and in response to stress.…”

Section: Discussionmentioning

confidence: 99%

Redox and acid‐base characterization of cytochrome b‐559 in photosystem II particles

Ortega

Hervás

Losada

1988

European Journal of Biochemistry

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The redox and acidlbase states and midpoint potentials of cytochrome b-559 have been determined in oxygenevolving photosystem I1 (PS 11) particles at room temperature in the pH range from 6.5 to 8.5. At pH 7.5 the fresh PS I1 particles present about 213 of their cytochrome b-559 in its reduced and protonated (non-autooxidizable) high-potential form and about 1/3 in its oxidized and non-protonated low-potential form. Potentiometric reductive titration shows that the protonated high-potential couple is pH-independent (Eo, + 380 mV), whereas the low-potential couple is non-protonated and pH-independent above pH 7.6 (Eo, pH > 7.6, + 140 mV), but becomes pH-dependent below this pH, with a slope of -72 mV/pH unit. Moreover, evidence is presented that in PS I1 particles cytochrome b-559 can cycle, according to its established redox and acidlbase properties, as an energy transducer at two alternate midpoint potentials and at two alternate pKa values. Red light absorbed by PS I1 induces reduction of cytochrome b-559 in these particles at room temperature, the reaction being completely blocked by dichlorophenyldimethylurea.The location and function of cytochrome b-559 in the chloroplast electron-transport chain(s), although widely and intensively investigated, have remained enigmatic and controversial [l -81. Understanding the oxidation/reduction potential and pH dependence of this cytochrome in high-potential (HP) low-potential (LP) forms is essential for assessing its role as both an electron carrier and a proton carrier, but in this regard the literature is ambiguous and includes incomplete and contradictory data. Equally important is deciding whether cytochrome b-559 is reduced or oxidized by light absorbed by photosystem 11, since the reported results are also contradictory in this respect. [15] this effect, which is reversible upon raising the pH, is inhibited by 3-(3',4'-dichloropheny1)-1,l'-dimethylurea (+ 395 mV at pH 7.8; + 335 mV at pH 5.0, and + 380 mV at pH 5.0 and in the presence of dichlorophenyldimethylurea). More recently our group [19 -211 obtained solid evidence that in spinach thylakoids the HP couple of cytochrome b-559 is pH-independent in the pH range between 6.5 and 8.5 (Eb, + 340 mV), whereas the LP couple is pH-independent above pH 7.6 (Eo, pH > 7.6, + 75 mV), but becomes pH-dependent below this pH, with a slope of -60 mV/pH unit. According to our proposal [6,21] the cytochrome functions at low potential as electron acceptor of PS 11, and at high potential as electron donor to PS I, thus acting as a transducer of redox energy into acidlbase energy between the two photosystems.The HP form of cytochrome b-559 is labile towards treatments, such as aging, sonication, mild heating, incubation in Tris buffer or Triton X-100, addition of either carbonylcyanide p-trifluoromethoxyphenylhydrazone or carbonylcyanide 3-chlorophenylhydrazone (CCCP), trypsin digestion, NaCl washing, that may alter or disrupt membrane structure and that cause what is usually considered an 'irreversible' conversion to the LP fo...

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Section: Discussionmentioning

confidence: 99%

Redox and acid‐base characterization of cytochrome b‐559 in photosystem II particles

Ortega

Hervás

Losada

1988

European Journal of Biochemistry

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“…Gel filtration was performed with a Superose 12 HR 10/30 column (Pharmacia) equilibrated with buffer A. An Aminco DW-2 spectrophotometer was used to quantify cytochrome b-559, using the dithionite-reduced minus ferricyanide-oxidized difference spectrum and assuming a differential extiction coefficient of 17 500 M-' cm-' (Cramer et al, 1986).…”

Section: Methodsmentioning

confidence: 99%

Characterization by electron microscopy of isolated particles and two-dimensional crystals of the CP47-D1-D2-cytochrome b-559 complex of photosystem II

Dekker¹,

Betts²,

Yocum³

et al. 1990

Biochemistry

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A photosystem II complex containing the reaction center proteins Dl and D2, a 47-kDa chlorophyll-binding protein (CP47), and cytochrome 6-559 was isolated with high yield, purity, and homogeneity; small but well-ordered two-dimensional crystals were prepared from the particles. The crystals and the isolated particles were analyzed by electron microscopy using negatively stained specimens. The t This research was supported by National Science Foundation Grant DCB 89-04075 to C.F.Y. and by grants from the Deutsche Forschungs Gemeinschaft, Sonderforschungsbereich 312, to E.J.B.

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“…since each polypeptide contains only a single histidine residue capable of occupying a coordination position of the Fe in the two hemes [3].…”

Section: Rw(z)laih(6)glav(lo)ptvsflgsisamq Fiqr(27) Bmentioning

confidence: 99%

“…The two polypeptides are present in 1: 1 stoichiometry [ 121. Both have a single membrane-spanning region [3] with the following amino acid sequence: NH,...RY (2)WVIH (6) …”

Section: Introductionmentioning

confidence: 99%

Spectral and thermodynamic properties of the two hemes of the D1D2cytochrome b‐559 complex of spinach

1994

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In agreement with previous work [Shuvalov, Heber and Schreiber (1988) FEBS Lett. 258, 277311 two hemes (low potential (LP) and extra low potential (XLP)) per two pheophytins were found in isolated DlD2Cyt b-559 complexes. Reductive and oxidative redox titrations demonstrate that the E,,, of the LP form is at about +150 mV. It is independent of pH between pH 7.2 and 9.4. The XLP heme is autoxidizable at pH 7.2 and displays. at this pH. an E,,, of -45 mV. Both the LP and XLP hemes show absorption peaks at 559 nm. They are proposed to have bis-histidine ligation of the heme iron. At pH 9.4, the XLP heme splits into two forms. One of them has an E,,, of +40 mV, and absorption peaks at 559 nm showing the bis-histidine ligation. The other displays an E,,, of -220 mV and the peak is shifted to 562 nm. This last form is proposed to be due to the incorporation of OH-which occupies the 6th coordination position of the heme Fe(II1) at high pH. The pK value for the conversion of the XLP heme is close to 7.7. In a structure simulation of the a-helices of a-and /I-polypeptides, the B-polypeptide, but not the a-polypeptide, reveals a distance between the histidine N and the heme Fe which permits stable N-Fe coordination. In the a-polypeptide, OH-can be incorporated between N and Fe. The functional role of the two hemes of cyt b-559 is briefly discussed with respect to water oxidation and cychc electron transfer.

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On the structure and function of cytochrome b-559

Cited by 120 publications

References 48 publications

Redox and acid‐base characterization of cytochrome b‐559 in photosystem II particles

Redox and acid‐base characterization of cytochrome b‐559 in photosystem II particles

Characterization by electron microscopy of isolated particles and two-dimensional crystals of the CP47-D1-D2-cytochrome b-559 complex of photosystem II

Spectral and thermodynamic properties of the two hemes of the D1D2cytochrome b‐559 complex of spinach

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