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D W Krogmann

Publications and source records attributed to D W Krogmann.

At least 19 recordsLinked to original sources
PubMed2001

Structures of cytochrome c-549 and cytochrome c6 from the cyanobacterium Arthrospira maxima.

Cytochrome c(6) and cytochrome c-549 are small (89 and 130 amino acids, respectively) monoheme cytochromes that function in photosynthesis. They appear to have descended relatively recently from the same ancestral gene but have diverged to carry out very different functional roles, underscored by the large difference between their midpoint potentials of nearly 600 mV. We have determined the X-ray crystal structures of both proteins isolated from the cyanobacterium Arthrospira maxima. The two structures are remarkably similar, superimposing on backbone atoms with an rmsd of 0.7 A. Comparison of the two structures suggests that differences in solvent exposure of the heme and the electrostatic environment of the heme propionates, as well as in heme iron ligation, are the main determinants of midpoint potential in the two proteins. In addition, the crystal packing of both A. maxima cytochrome c-549 and cytochrome c(6) suggests that the proteins oligomerize. Finally, the cytochrome c-549 dimer we observe can be readily fit into the recently described model of cyanobacterial photosystem II.

Amino Acid Sequence↗
PubMed2000

The golden age of biochemical research in photosynthesis.

The perspectives and enthusiasms recorded in this review describe the events I witnessed and, in small ways, contributed to. Two great rewards emerged from my experiences - the pleasure of doing experiments and the great wealth of friendships with students and colleagues. As a graduate student, phenomena appeared at the bench before me which clarified the coupling of electron transport to ATP synthesis. My first PhD graduate student measured concentrations of pyridine nucleotides in chloroplasts and his results have been often confirmed and well used. All of the many graduate students who followed contributed to our understanding of photosynthesis. I have taken much pleasure from documenting the details of photosynthetic phosphorylation and electron transport in cyanobacteria. Studies of the 'c' type cytochromes in these organisms continue to fascinate me. My experiences in government in its efforts to promote research are unusual, perhaps unique. A rare event outside the laboratory - a natural bloom of cyanobacteria - stimulated new thoughts and special opportunities for laboratory science. Photosynthesis seems magisterial in its shaping of our planet and its biology and in the details of its cleverness that were revealed in the time of my witness.

Journal Article↗
PubMed1997

The orange carotenoid protein of Synechocystis PCC 6803.

A water soluble protein with the carotenoid 3'-hydroxyequinenone bound to it has been purified from the cyanobacterium Synechocystis PCC 6803. Based on partial amino acid sequencing of the protein, oligonucleotides were synthesized and used as primers for PCR to obtain a substantial fragment of the gene. This DNA was sequenced and the sequence data and the size of the protein indicate that the protein is encoded by gene slr 1963 in the Kazusa DNA sequence data bank containing the Synechocystis 6803 genome. This protein is very similar to 3'-hydroxyechinenone proteins found in several other cyanobacteria but it shows very little resemblance in its amino acid or gene sequence to other carotenoid binding proteins. The protein binds 1-2 molecules of 3'-hydroxyechinenone and is slowly cleaved by proteases in the cell extract to give a molecule of approximately half the original mass which retains the carotenoid and which shows a striking change in color.

Amino Acid Sequence↗
PubMed1997

Crystals of the carotenoid protein from Arthrospira maxima containing uniformly oriented pigment molecules.

Crystals of a carotenoid protein from the cyanobacterium Arthrospira maxima have been grown in space group C2 with unit-cell dimensions a = 219.6, b = 40.3, c = 75.5 A and beta = 95.5 degrees. The crystals diffract X-rays to 2.3 A resolution and display unusual optical properties in polarized light that suggest that all of the carotenoid molecules in the crystals are oriented similarly. A slight increase in the concentration of a crystallization additive in the mother liquor induces macroscopic twinning, which is also visible when the crystals are illuminated with polarized light.

Journal Article↗
PubMed1994

Cloning and sequence analysis of the gene encoding the low potential cytochrome c of Synechocystis PCC 6803.

The gene for the low potential cytochrome c (petK) was isolated from a genomic library of Synechocystis PCC 6803. The nucleotide sequence of this gene contains two regions with sequence similarity to two regions in the gene for the high potential cytochrome c6 of the organism. The sixth iron ligand can be identified with a conserved histidine. Experiments demonstrate the reduction of the low potential cytochrome by reduced ferredoxin II. The heme of the cytochrome is flanked by lysines which may be involved in orienting the ferredoxin near the site of electron donation.

Amino Acid Sequence↗
PubMed1991

The low-potential cytochrome c of cyanobacteria and algae.

A water-soluble, low-potential cytochrome c-550 is found in some cyanobacteria and eukaryotic algae and has regions of sequence similarity to cytochrome c6. This cytochrome appears to be involved in a fermentation that sustains the organisms during prolonged periods of dark, anaerobic conditions.

Cyanobacteria↗
PubMed1989

Plastocyanin cytochrome f interaction.

Spinach plastocyanin and turnip cytochrome f have been covalently linked by using a water-soluble carbodiimide to yield an adduct of the two proteins. The redox potential of cytochrome f in the adduct was shifted by -20 mV relative to that of free cytochrome f, while the redox potential of plastocyanin in the adduct was the same as that of free plastocyanin. Solvent perturbation studies showed the degree of heme exposure in the adduct to be less than in free cytochrome f, indicating that plastocyanin was linked in such a way as to bury the exposed heme edge. Small changes were also observed when the resonance Raman spectrum of the adduct was compared to that of free cytochrome f. The adduct was incapable of interacting with or donating electrons to photosystem I. Peptide mapping and sequencing studies revealed two sites of linkage between the two proteins. In one site of linkage, Asp-44 of plastocyanin is covalently linked to Lys-187 of cytochrome f. This represents the first identification of a group on cytochrome f that is involved in the interaction with plastocyanin. The other site of linkage involves Glu-59 and/or Glu-60 of plastocyanin to as yet unidentified amino groups on cytochrome f. Euglena cytochrome c-552 could also be covalently linked to turnip cytochrome f, although with a lower efficiency than spinach plastocyanin. In contrast, a variety of cyanobacterial cytochrome c-553's and a cyanobacterial plastocyanin could not be covalently linked to turnip cytochrome f.

Amino Acid Sequence↗
PubMed1989

The amino acid sequence of cytochrome c553 from Microcystis aeruginosa.

Cytochrome c553 is an electron donor to P700 in the photosynthetic electron transfer chain of cyanobacteria and eukaryotic algae. We have purified this cytochrome from the cyanobacterium Microcystis aeruginosa and determined its amino acid sequence. When the amino acid sequence of this protein is compared to sequences of cytochromes c553 from other organisms, one sees that the evolution of net charge is more pronounced than the evolution of overall structure, further documenting a pronounced shift in the isoelectric point of this protein during the evolution of cyanobacteria. Cyanobacteria and algae also contain cytochrome c550 (Mr 15,500) which is quite different from cytochrome c553 (Mr 10,500). When the amino acid sequence of cytochrome c553 is compared to that of cytochrome c550, two regions of similar sequence are recognized.

Amino Acid Sequence↗
PubMed1989

The amino acid sequence of low-potential cytochrome c550 from the cyanobacterium Microcystis aeruginosa.

The low-potential cytochrome c550 has been purified from the cyanobacterium Microcystis aeruginosa and its amino acid sequence has been determined. The protein contains 135 amino acid residues with the Cys-X-X-Cys-His heme binding site at residues 37 to 41. The sequence from residue 28 to 45 shows similarity to cytochrome c553 residues 1 to 18 when the heme binding sites are aligned. Another region of similarity is in the carboxyl-terminal regions of these two proteins. The two aligning regions of cytochrome c553 correspond to helical segments in other related cytochromes. A partial sequence of cytochrome c550 from Aphanizomenon flos-aquae was obtained and showed a 48% identity to the sequence of the M. aeruginosa cytochrome. The single methionine residue in cytochrome c550 of M. aeruginosa occurs at position 119 but there is no methionine in this region in the A. flos-aquae cytochrome, indicating that methionine is not the sixth ligand to the heme iron atom. Histidine 92 is a possible sixth ligand in M. aeruginosa cytochrome c550. The far-uv circular dichroism spectrum indicates that this protein is approximately 17% alpha helix, 42% beta-pleated sheet, and 41% random coil.

Amino Acid Sequence↗
PubMed1987

Kinetics of reduction by free flavin semiquinones of algal cytochromes and plastocyanin.

It had been shown that plastocyanin and cytochrome c-553 are functionally interchangeable in algae and that the physiological electron transfer reactions are sensitive to ionic strength. The isoelectric points of these proteins range from very acidic to basic depending upon species, and naturally occurring amino acid substitutions of charged residues have been shown to affect the kinetics of electron transfer, presumably through alteration of protein net charge. We have now shown that these naturally occurring amino acid substitutions also affect the kinetics of nonphysiological electron transfer reactions, and that we can quantitate the extent of nonconservation of charge. The reduction of plant and algal proteins by FMN semiquinone is sensitive to ionic strength and the effects can be correlated with net protein charge with regard to sign, but not to magnitude, with the charge at the site of electron transfer varying from +3 through 0 to -3. We had previously observed in a large variety of electron transfer proteins from bacteria (G. Tollin, T. E. Meyer, and M. A. Cusanovich (1986) Biochim. Biophys. Acta 853, 29-41) that charge localized at the site of electron transfer, rather than net protein charge, was more likely to affect kinetics. This also appears to be the case with the algal proteins. By comparison of protein structures, we have been able to predict which substitutions are likely to be responsible for the kinetic effects in the algal proteins and to discuss the implications of such changes for function.

Amino Acid Sequence↗
PubMed1987

Highly efficient purification of the 33-, 24-, and 18-kDa proteins in spinach photosystem II by butanol/water phase partitioning and high-performance liquid chromatography.

The 33-, 24-, and 18-kDa proteins involved in photosynthetic oxygen evolution were purified from spinach photosystem II particles by butanol/water phase partitioning and high-performance liquid chromatography with a silica-based cation-exchange column. With this procedure a significant improvement was made in the time required for the purification and also in the amount and purity of the proteins. The N-terminal sequence of amino acid was determined for the purified proteins. Partial degradation of the proteins, which sometimes occurred in the purification, was not detected in the new procedure.

Amino Acids↗
PubMed1986

Blooms of cyanobacteria on the potomac river.

Blooms of cyanobacteria have appeared on the Potomac River near Washington, DC in years of drought and low river volume. The location of the bloom may be related to tidal activity. In 1983, the bloom of Microcystis aeruginosa used ammonia as its nitrogen source and contained low levels of toxic peptides. Cells collected from this bloom proved to be homogeneous and were an excellent source material for the isolation of proteins involved in photosynthesis.

Journal Article↗
PubMed1986

Isolation and sequence of the gene for ferredoxin I from the cyanobacterium Anabaena sp. strain PCC 7120.

The structural gene for ferredoxin I, petF, from the cyanobacterium Anabaena sp. strain PCC 7120 has been isolated from a recombinant lambda library. Mixtures of tetradecanucleotides and heptadecanucleotides, each containing all possible DNA sequences corresponding to two separate regions of the ferredoxin amino acid sequence, were synthesized and used as hybridization probes to identify a genomic clone containing the coding sequence for the petF gene. The sequence of the entire petF coding region and portions of the 3'- and 5'-flanking regions was determined. The DNA sequence of petF suggests that, in contrast to the nucleus-encoded plant protein, cyanobacterial apoferredoxin is not synthesized as a higher-molecular-weight precursor. The Anabaena petF gene is a single-copy gene. During growth on complete medium it was transcribed into a monocistronic mRNA species of approximately 500 bases that initiated 100 base pairs upstream from the petF coding region.

Amino Acid Sequence↗
PubMed1983

Three c-type cytochromes from the red alga Porphyridium cruentum.

Three c-type cytochromes were isolated from the red alga, Porphyridium cruentum, and partially characterized. The cytochrome c553 was an extrinsic membrane protein which was easily released to the aqueous phase with a yield of 10 to 15 mg pure protein/100 g cells. The properties of this cytochrome were similar to other algal and cyanobacterial cytochromes which function as Photosystem I electron donors. Absorption maxima in reduced cytochrome c553 were at 552.8, 521.8, and 415.6 nm. The molecular mass was 10 kDa, the redox potential was +340m V, and the pI was 4.3. The near-infrared absorption band of ferricytochrome was found to titrate with a single pK of 9.5. In addition to the loss of the near-infrared band at alkaline pH, other spectral changes were noted in the ferrocytochrome. The most obvious change was that of the alpha-band shifting to 550 nm in the dithionite-reduced cytochrome at alkaline pH. Small quantities of a cytochrome c550 were detected in some preparations of P. cruentum. This cytochrome had absorption maxima in the reduced form at 550, 522, and 416 nm. The pI was 4.1. This cytochrome was isolated in the oxidized form and was not ascorbate-reducible. The third c-type cytochrome isolated from P. cruentum was an intrinsic membrane protein analogous to higher plant cytochrome f. The absorption maxima in the reduced cytochrome were at 553.8, 522.5, and 421.0 nm. Cytochrome f was always isolated in the reduced form with a yield of 1 to 1.5 mg/100 g of algal membranes. The cytochrome f was unstable at 4 or -20 degrees C. The molecular mass was 26 kDa, and the pI was 6.5. Photosynthetically active vesicles from P. cruentum were prepared and exogenous cytochrome c553 stimulated Photosystem I-dependent activity but not reactions dependent on both photosystems. Antibody to cytochrome c553 had no effect on photochemical activity.

Chemical Phenomena↗
PubMed1982

Structure and heme environment of ferrocytochrome c553 from 1H NMR studies.

Cytochrome c553 is a photosynthetic electron transport protein found in algae and cyanobacteria. We have purified cytochromes c553 from five cyanobacteria and studied the structures of the ferrocytochromes by 1H NMR spectroscopy at 360 and 470 MHz. Using standard NMR techniques and by comparing the amino acid sequences of four cytochromes c553 with their 1H NMR spectra, we have assigned in the spectrum of the Aphanizomenon flos-aquae protein 18 resonances to specific amino acid residues and 12 resonances to specific heme protons. Steady state and truncated driven nuclear Overhauser enhancement experiments indicate that a tyrosine and methionine are located near pyrrole ring IV of the heme and that a phenylalanine ring is near the heme alpha-mesoproton. The general folding of the cytochrome c553 protein backbone appears to resemble that of Pseudomonas aeruginosa cytochrome c551, but the chirality of the cytochrome c553 axial methine sulfur is R, the same as that of horse heart cytochrome c.

Cyanobacteria↗
PubMed1980

Cytochrome f from spinach and cyanobacteria. Purification and characterization.

Cytochrome f has been purified from spinach chloroplasts and from the photosynthetic membranes of the cyanobacterium Spirulina maxima. The spinach protein has an isoelectric point of 5.2 and gives a single band on isoelectric focusing gels. The S. maxima cytochrome shows a major band with a pI of 4.01 and a minor band with a pI of 3.97. S. maxima cytochrome f has a molecular weight approximately 38,000 and is monomeric, while the spinach protein is slightly smaller, approximately 36,000 daltons, and aggregates to form an octamer. S. maxima cytochrome f has an E'0 of +339 mV which is close to that of cytochromes f from higher plants. The NH2-terminal amino acid sequences of the cytochromes show striking similarities. Spinach cytochrome f shows a clear preference for oxidation by spinach plastocyanin and S. maxima cytochrome f is more readily oxidized by its in vivo reaction partner, cytochrome c553.

Amino Acid Sequence↗
PubMed1980

Electron donation to photosystem I.

Electron donation to photosystem I was studied in highly resolved particles from spinach. Divalent cations increased the efficiency of electron donation from spinach plastocyanin to P700(+) through a decrease in the apparent K(m) for plastocyanin. Cytochrome f was not an efficient electron donor for P700(+) in the presence or absence of divalent cations. Cytochrome f photooxidation could be observed in the presence of both plastocyanin and divalent cations.The efficiencies of electron donors from eukaryotic and prokaryotic algae to P700(+) were also examined. Divalent cations enhanced the effectiveness of electron donors from eukaryotic organisms, while inhibiting electron donors from prokaryotic organisms. The prokaryotic electron donors were also much more efficient donors than were the electron donors from eukaryotic organisms. A correlation between the K(m) for the electron donor and its isoelectric point suggests that the net charge on the donor protein is a major determinant of the efficiency for electron donation. The data presented raise interesting questions with respect to the evolution of electron donation to photosystem I and the possibility of an additional electron carrier between plastocyanin and P700(+).

Journal Article↗