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W Wehrmeyer

Publications and source records attributed to W Wehrmeyer.

14 recordsLinked to original sources
PubMed1994

Utilization of light for nitrogen fixation by a new synechocystis strain is extended by its low photosynthetic efficiency.

Performance of photosynthesis and nitrogenase activity in a novel cyanobacterium, Synechocystis sp. strain BO 8402, isolated from Lake Constance, located at the northern fringe of the Alps in central Europe, and of a stable derivative, strain BO 9201, were examined. Strain BO 8402 is characterized by an extraordinarily high level of autofluorescence originating from paracrystalline phycobiliprotein-linker complexes located in inclusion bodies (W. Reuter, M. Westermann, S. Brass, A. Ernst, P. Böger, and W. Wehrmeyer, J. Bacteriol. 176:896-904, 1994). Energy transfer between paracrystalline phycobiliproteins and the photosystems is inefficient, resulting in a high oxygen compensation point and a decreased growth rate. The derivative strain BO 9201 exhibits hemidiscoidal phycobilisomes that support a high growth rate, even under low light intensities. Because of the differences in photosynthetic performance, anaerobic light-stimulated nitrogenase activity is maintained at higher light intensity in the original strain BO 8402 than in the derivative strain BO 9201. The results indicate that the formation of paracrystalline phycobiliproteins in Synechocystis sp. strain BO 8402 represents a hitherto-unknown means for a unicellular cyanobacterium to extend its capacity to fix nitrogen in the light.

Journal Article↗
PubMed1994

Structure, composition, and assembly of paracrystalline phycobiliproteins in Synechocystis sp. strain BO 8402 and of phycobilisomes in the derivative strain BO 9201.

The phycobiliproteins of the unicellular cyanobacterium Synechocystis sp. strain BO 8402 and its derivative strain BO 9201 are compared. The biliproteins of strain BO 8402 are organized in paracrystalline inclusion bodies showing an intense autofluorescence in vivo. These protein-pigment aggregates have been isolated. The highly purified complexes contain phycocyanin with traces of phycoerythrin, corresponding linker polypeptides LR35PC and LR33PE (the latter in a small amount), and a unique colored polypeptide with an M(r) of 55,000, designated L55. Allophycocyanin and the core linker polypeptides are absent. The substructure of the aggregates has been studied by electron microscopy. Repetitive subcomplexes of hexameric stacks of biliproteins form extraordinary long rods associated side by side in a highly condensed arrangement. Evidence that the linker polypeptides LR35PC and LR33PE stabilize the biliprotein hexamers is presented, while the location and function of the colored linker L55 remain uncertain. The derivative strain BO 9201 contains established hemidiscoidal phycobilisomes comprising phycoerythrin, phycocyanin, and allophycocyanin as well as the corresponding linker polypeptides. The core-membrane linker protein (LCM), and two polypeptides with M(r)s of 40,000 and 45,000 which are present in small amounts, exhibit strong cross-reactivity in Western blot (immunoblot) analysis using an antibody directed against the colored LCM of a Nostoc sp. In contrast, strain BO 8402 exhibits no polypeptide with a significant immunological cross-reactivity in Western blot analysis. Physiological and genetic implications of the unusual pigment compositions of both strains are discussed.

Bacterial Proteins↗
PubMed1993

Core substructure of the hemiellipsoidal phycobilisome from the red alga Porphyridium cruentum.

The allophycocyanin core of hemiellipsoidal phycobilisomes from the red alga, Porphyridium cruentum, was isolated by chromatography on hydroxylapatite and subsequent density gradient centrifugation. Electron microscopy of negatively stained core complexes revealed a tricylindrical structure with a width of 21 to 23 nm in face view and a depth of 12 to 14 nm in side view. Fluorescence emission spectra of these complexes were similar to those of whole phycobilisomes confirming the presence of the two "terminal energy acceptors" allophycocyanin B (APB) and the high molecular linker polypeptide LCM. The polypeptide composition analyzed by SDS-PAGE showed the "anchor" polypeptide LCM, alpha AP, alpha APB, beta AP subunits, a low molecular weight linker with M(r) 13,500 and a blue-colored polypeptide of M(r) 19,800. A complex containing APB could be isolated from a "trimeric" allophycocyanin fraction of the density gradient by agarose gel electrophoresis in the presence of ampholytes. This complex shows a polypeptide composition of (alpha APB alpha AP2 beta AP3).L13.5C and contributes to the core with 30 to 35% of total "trimers". In comparison to the allophycocyanin cores from hemidiscoidal phycobilisomes of cyanobacteria and red algae, all data concerning the core of the hemiellipsoidal phycobilisomes from Porphyridium cruentum strongly suggest that there is no increase in size but an increase in its APB content. A model comprising the allophycocyanin core and the membrane integral photosystem II particles presents the structural and possible functional consequences of the results.

Bacterial Proteins↗
PubMed1993

Core substructure in phycobilisomes of red algae. II. The central part of the tricylindrical core--APCM--a constituent of hemidiscoidal phycobilisomes of Rhodella violacea.

The central part of the tricylindrical core of phycobilisomes from Rhodella violacea was isolated by hydroxylapatite adsorption chromatography followed by density gradient centrifugation. In the electron microscope negatively stained APCM complexes showed a tricylindrical face view with an edge length of 20 to 24 nm and a thickness of 9 to 10 nm in profile view. These complexes had a M(r) of 900,000, and a sedimentation coefficient 24S. The fluorescence emission maximum at room temperature lay at 671 nm when excited at 590 nm. The presence of the high molecular linker polypeptide LCM exclusively in APCM and the existence of beta AP19.5, alpha AP18, and beta AP17 were demonstrated in SDS-polyacrylamide gel electrophoresis. The presence of "trimeric" allophycocyanin complexes in a separate band, with a sedimentation coefficient 6S, confirms the uncoupling of these complexes from the core; their maximal fluorescence at 680 nm in the second derivative hints at alpha AP-8. The results indicate a high conformity in the molecular organization of the core of hemidiscoidal phycobilisomes of red algae (Rhodella violacea) and cyanobacteria (Mastigocladus laminosus).

Bacterial Proteins↗
PubMed1990

Isolation of allophycocyanin B from Rhodella violacea results in a model of the core from hemidiscoidal phycobilisomes of rhodophyceae.

Two 'trimeric' allophycocyanin complexes could be isolated from the hemidiscoidal phycobilisomes of Rhodella violacea. AP = (alpha *AP alpha 2AP beta 2AP beta *AP) and APB = (alpha *AP alpha AP alpha APB beta 2AP beta *AP). Lc13.5APB. The isolation was performed by combined methods of gradient centrifugation, hydroxylapatite chromatography and 'native' polyacrylamide gel electrophoresis. AP showed the well-known spectral characteristics of allophycocyanin without linker polypeptide. APB is characterized by its long wavelength absorbing shoulder (675 nm) and fluorescence emission (682 nm), respectively. The existence of two low molecular linker polypeptides Lc12.5 and Lc13.5APB in the phycobilisomes of Rhodella violacea, their stoichiometric calculations and the localization of Lc13.5APB in allophycocyanin B facilitated the construction of a model of the phycobilisome core.

Electrophoresis, Polyacrylamide Gel↗
PubMed1990

The complete amino-acid sequence and the phylogenetic origin of phycocyanin-645 from the cryptophytan alga Chroomonas sp.

The first complete amino-acid sequence of the cryptomonad phycobiliprotein phycocyanin-645 from Chroomonas sp. is presented. The alpha 1-subunit contains 70 amino-acid residues and the alpha 2-subunit 80 residues. In each of the alpha-subunits a green, 697-nm absorbing chromophore is covalently bound to Cys18. Both alpha-subunits contain a high number of charged residues. The phycocyanin-645 beta-subunit consists of 177 amino-acid residues. Two phycocyanobilin chromophores are singly bound to Cys beta 82 and Cys beta 158. A purple cryptoviolin-like chromophore is doubly bound to Cys beta 50 and Cys beta 61. Sequence comparisons revealed that the phycocyanin-645 beta-subunit is closely related to red algal phycoerythrin (73% identical amino-acid residues) and not so close to C-phycocyanin (55% identical amino-acid residues). The phycocyanin-645 alpha-subunits represent a special type of phycobiliprotein and a direct relationship to other phycobiliproteins or any light-harvesting polypeptide-pigment complexes could not be derived by sequence comparisons.

Amino Acid Sequence↗
PubMed1988

Diaphototaxis and gravitaxis in a freshwater Cryptomonas.

Phototaxis and gravitaxis are characterized in a freshwater species of the flagellate Cryptomonas. The phototactic orientation in this limnetic species is unusual and differs from all other Cryptomonas species studied so far: At both low (< or = 1O W m-2) and higher fluence rates it orients perpendicular to the light beam (diaphototaxis) while another freshwater Cryptomonas species (strain CR-1) is restricted to positive phototaxis and the marine species, C. maculata, shows both a positive and a more pronounced negative phototaxis. The mechanism of light direction detection seems to depend on a periodic shading or irradiation mechanism as confirmed by the disturbance of phototaxis in the presence of high viscosity media. In addition, this freshwater species possesses a rather pronounced negative gravitaxis which is only partially modified by phototaxis. The ecological consequences of this behavior are discussed.

Eukaryota↗
PubMed1985

Structural studies on cryptomonad biliprotein subunits. Two different alpha-subunits in Chroomonas phycocyanin-645 and Cryptomonas phycoerythrin-545.

The N-terminal amino-acid sequences of two green alpha-subunit fractions from Chroomonas phycocyanin-645 and from two violet alpha-subunit fractions from Cryptomonas phycoerythrin-545 reveal that these cryptomonad biliproteins each contain two different alpha-subunits. The chromophore binding sites at the cysteine residues in positions 18 or 19 are homologous to the chromophore binding site at cysteine position 84 in cyanobacterial biliproteins. The sequence homologies of the beta-subunits to cyanobacterial biliproteins are higher than those of the alpha-subunits. Cryptomonas phycoerythrin-545 alpha-subunits contain a gamma-hydroxylysine residue at the fourth position of the polypeptide chains. 50%-75% of the total sequence of the alpha-subunits was determined by N-terminal amino-acid sequence analysis. The alpha-subunits of the Cryptomonad biliproteins are smaller than the alpha-subunits of the cyanobacterial biliproteins. Comparing sequence homologies we found 60 amino-acid residues less at the N-terminus of Cryptomonad biliproteins than in cyanobacterial biliproteins.

Amino Acid Sequence↗
PubMed1980

Biliprotein assembly in the disc-shaped phycobilisomes of Rhodella violacea. Electron microscopical and biochemical analysis of B-phycoerythrin and B-phycoerythrin--C-phycocyanin aggregates.

Hexameric B-phycoerythrin (alpha beta)6 gamma is a double disc of about 10.7 x 4.3 nm; each single disc consists of a six membered periphery (alpha beta)3, the subunits of which are assumed to be associated in alternating positions with little or no staggering. A central subunit, almost certainly the gamma-subunit, penetrates both rings linking them tightly together. Hexameric C-phycocyanin (alpha beta)6 has the same construction but lacks this central subunit. In urea gel electrophoresis B-phycoerythrin I and II separate into three bands alpha, beta, and gamma in a relative molar ratio of 6:6:1. The molecular weights of the alpha-, beta-, gamma-subunits, estimated from SDS gels were 18 700, 18 700 and 29 200 and 18 300, 18 300 and 29 900 for B-phycoerythrin I and II, respectively, resulting in molecular weights of 253 600 and 249 500 for both hexameric aggregates. In density gradient centrifugation a sedimentation coefficient s20,w . 10(13) of 11.3 and a molecular weight of 244 000 were calculated. In sedimentation analyses of partially dissociated phycobilisomes a fragment consisting of two phycoerythrin hexamers with a sedimentation constant of 18 S (dodecamer) and tripartite units with two B-phycoerythrin hexamers associated with one polar C-phycocyanin hexamer with a sedimentation constant of 22 S were demonstrated. The corresponding molecular weight of the tripartite units, about 800 000, coincides well with morphological measurements on the basis of an average protein packing density and with earlier estimates on cross-linked biliprotein aggregates in gradient gel electrophoresis. The spaces of 1.2 to 3.0 nm between the hexamers give rise to a strong 6.0 nm periodicity within the tripartite units, the weak 3.0 nm periodicity originates from the double-rings of the constituent hexamers.

Centrifugation, Density Gradient↗
PubMed1978

Biliprotein assemble in the disc-shaped phycobilisomes of Rhodella violacea. On the molecular composition of energy-transfering complexes (tripartite units) forming the periphery of the phycobilisome.

Heterogeneous complexes with a molecular weight of about 790000 containing B-phycoerythrin (Bangiales phycoerythrin) and C-phycocyanin (Cyanophyceae phycocyanin) in a molar pigment ratio of 2:1 were isolated from purified, dissociated phycobilisomes. Electron microscopical investigations revealed structures of three discs aggregated face to face with an apparent distance of 1.5 nm between each disc. Two discs may represent phycoerythrin and one phycocyanin. The complexes are structurally identical with tripartite units of the phycobilisome periphery. Fluorescence data confirmed the integrity of isolated tripartite units. Excitation at 546 nm gives a fluorescence maximum at 644 nm, indicating intermolecular transfer of excitation energy from phycoerythrin to phycocyanin. Comparative subunit analyses and spectral data suggested that no allophycocyanin is present. Cross-linking experiments gave evidence for a polar arrangement of phycocyanin within the complex. This pigment itself is an aggregate of two smaller molecules each having a molecular weight of about 140000. Tripartite units contain all the phycoerythrin and phycocyanin of the phycobilisome. On this basis, a phycobilisome model is proposed which combines the aspects of biliprotein distribution, energy transfer and fine structure.

Macromolecular Substances↗
PubMed1977

Isolation and characterization of disc-shaped phycobilisomes from the red alga Rhodella violacea.

Disc-shaped phycobilisomes were purified from Triton X100 treated cell homogenates of the unicellular marine red alga, Rhodella violacea. Their absorption spectrum had principal maxima at 544 and 568 nm (B-phycoerythrin), 624 nm (C-phycocyanin) and a distinct shoulder at 652 nm (allophycocyanin). Intermolecular energy transfer within the phycobilisomes was clearly demonstrated by fluorescence data. Excited at 546 nm intact phycobilisomes showed a main fluorescence emission maximum at 665 nm, a minor one at 577 nm and a shoulder at 730 nm. Dissociated phycobilisomes revealed a composition of 58% B-phycoerythrin, 25% C-phycocyanin and 17% allophycocyanin under the cultural conditions used. Analytical methods resolved no other components than phycobiliproteins. In addition to the defined C-phycocyanin and two isoproteins of B-phycoerythrin a stable heterogeneous aggregate of B-phycoerythrin/C-phycocyanin was separated in considerable amounts. In the electron microscope negatively stained phycobilisomes appeared as elliptical aggregates having dimensions slightly above the values found in ultrathin sections and a detailed subunit structure. All observations and data suggest a new rhodophytan phycobilisome type in Rhodella violacea.

Cell Fractionation↗
PubMed1975

Cryptomonad biliprotein: phycocyanin-645 from a Chroomonas species.

The properties of phycocyanin-645 from the fresh water cryptomonad Chroomonas spec. were investigated after the pigment was isolated and purified by a combination of differential ammonium sulphate fractionation, gel filtration chromatography and ammonium sulphate gradient elution. Phycocyanin-645 is characterized by absorption maxima at 645 nm, 584 nm, 369 nm, 275 nm and shoulders at 340 nm and 620 nm. The CD spectrum has a negative maximum at 645 nm and a positive maximum at 584 nm with a shoulder at 610 nm. The fluorescence emission spectrum is asymmetrical and shows a maximum at 660 nm and a shoulder at approximately 715 nm. The molecular weight of the native phycocyanin-645, estimated by gel filtration, is 45000 for all multiple pigment forms below. Phycocyanin-645 is heterogeneous as revealed by isoelectric focusing with pIs at 7.03, 6.17, 5.75, 5.25 and 4.88, respectively, the main bands lying at pI 7.03 and pI 6.17. This was confirmed by polyacrylamide gel electrophoresis; five pigment compoents differing in mobility were found. We propose the term "multiple pigment forms" for these five phycocyanin-645 modifications. Calibrated SDS gel electrophoresis shows phycocyanin-645 to consist of three subunits, two light chains (alpha1, alpha2), having molecular weights of 9200 and 10400, respectively, and one heavy chain (beta), having a molecular weight of 15 500. Suggesting a 1:1:2 ratio between the subunits, the quaternary structure of the pigment molecule is alpha1beta--alpha2beta1.

Eukaryota↗
PubMed1975

B-Phycoerythrin from Rhodella violacea: characterization of two isoproteins.

Two isoproteins of the "native" B-phycoerythrin of the red alga, Rhodella violacea, were purified from crude extracts by preparative polyacrylamide gel electrophoresis and subsequently characterized. The slower moving pigment in gel electrophoresis was designated B-PE I, the faster as B-PE II. Both were found to occur in about equal amounts. B-PE I has a molecular weight of about 280000 and an IEP at 4.39, B-PE II a molecular weight of nearly 265000 and an IEP at 4.23. B-PE I and II are characterized by absorption maxima at 568 and 542 nm and a shoulder at 500 nm in the visible part of the absorption spectra. Their absorption coefficients at 542 nm differ with values of 5.54 and 5.63, respectively. The fluorescence emission spectra show a single maximum at 575 for B-PE I and at 578 nm for B-PE II. Both spectra have a shoulder at 630 nm. The fluorescence yield of B-PE II is lower by 25%. In calibrated SDS gel electrophoresis of the purified pigments B-PE I and II show two subunits of molecular weights of 18900 and 29200 and 18500 and 29900, respectively. Quantitative amino acid analyses indicated, that the isoproteins are very similar. B-PE II, however, has a significantly higher content of acidic amino acids and a lower percentage of basic residues, which is in keeping with its lower isoelectric point. Functional aspects of the occurrence of two isoproteins of B-phycoerythrin are discussed.

Amino Acids↗