Structures of antenna complexes of several Rhodospirillales from their resonance Raman spectra

Robert, Bruno; Lutz, Marc

doi:10.1016/0005-2728(85)90048-9

Cited by 128 publications

(106 citation statements)

References 16 publications

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“…rubrum chromatophores (32,37). The frequency of these bands matches those obtained for LH1 purified from >10 different strains of purple bacteria by Soret resonance Raman in 1985 (38). It was concluded at the time that the central Mg ion of all the bchls present in the complexes were penta-coordinated and that the 1642-cm-' band was degenerate, containing contributions from both C2 acetyl carbonyls of the two bchl a molecules present in the minimal unit (a44 dimer) being involved in similar intermolecular interactions.…”

Section: Resultssupporting

confidence: 74%

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Modification of a hydrogen bond to a bacteriochlorophyll a molecule in the light-harvesting 1 antenna of Rhodobacter sphaeroides.

Olsen

Sockalingum

Robert

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

119

141

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Site-directed mutagenesis has been used to examine the function of a highly conserved aromatic residue, darp43, in the light-harvesting 1 antenna ofthe photosynthetic bacterium Rhodobacter sphaeroides. In this antenna dfrp43 is thought to be located near the putative binding site for bacteriochlorophyll; in this work it was changed to both Tyr and The photosynthetic apparatus of the purple bacterium Rhodobacter sphaeroides consists of a membrane protein complex, the reaction center (RC), surrounded by a core light-harvesting complex, LH1, also referred to as B875, in a fixed stoichiometry of -12 LH1 a(3 dimers per RC. An additional peripheral light-harvesting complex, LH2, also referred to as B800-850, occurs in variable amounts in response to environmental levels of light and oxygen (1, 2). The structure of the RC of Rb. sphaeroides is known to atomic resolution (3, 4); however, the structures of the LH1 and LH2 complexes are not known, although diffracting crystals ofvarious LH complexes have been reported (5-10). As yet, these structures have not been solved, so it is necessary to employ other methods such as mutagenesis and spectroscopy to obtain relevant data. As a result of these approaches, more information is becoming available on the interaction of the chromophores of LH1 and LH2 with nearby residues of the antenna polypeptides (11,12). These data can be used to test existing model structures derived from spectroscopic and electrophoretic mobility studies of wild-type (WT) complexes. The models that have been proposed for bacterial LH complexes all follow a similar pattern in that the af8 heterodimer, which in the case of LH1 would bind 2 bacteriochlorophyll (bchl) molecules, is considered to be the minimum possible building block. The topology and conformation of these subunits are thought to be similar, each with a cytoplasmically exposed N terminus, a single transmembrane helix, and a periplasmic C terminus. There are indications of turns at or near the membrane interfaces (13 (20), and Rhodocyclus gelatinosus (21), leading to the speculation that this bchl dimer is the building block of the LH1 complex. Characterization of the B820 form (22) supports the idea that it is an excitonically coupled bchl a dimer. Moreover, resonance Raman measurements of the B820 showed that it differed from the B873 form in the interactions of the C2 acetyl carbonyl; the loss of a H bond was one possible explanation of the Raman data. A more detailed Raman study of the LH1 ofRs. rubrum G9 has shown that upon formation of the B820, the strength of one H bond was increased (23 FT, Fourier transform; WT, wild type; P-OG, n-octyl P-Dglucopyranoside; ODPS, n-octyldipropyl sulfoxide. 7124The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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Section: Resultssupporting

confidence: 74%

“…The 1640-cm'1 peak has been previously asned to H-bonded C2 acetyl carbonyl groups of both bacteriochlorophylis in the light-harvesting 1 antenna dimer [Robert, B. & Lutz, M. (1985) RhochIm. Riophys.…”

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confidence: 99%

Modification of a hydrogen bond to a bacteriochlorophyll a molecule in the light-harvesting 1 antenna of Rhodobacter sphaeroides.

Olsen

Sockalingum

Robert

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

119

141

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“…This might indicate that the conformation of the B870ru and p polypeptides is not markedly affected by the removal of the 9 N-terminal amino acids in the B87Ocz subunits and the 22 N-terminal amino acids in the B87OJ subunit. The conserved histidines (His3' in B870cu [8] and His3* in B870@ [7]), which are buried within the membrane, are proposed to function as a ligand for the Mg2+ of the Bchl ring [22]. Furthermore, a recent X-ray structure analysis of the Rps.…”

Section: Discussionmentioning

confidence: 99%

Localization of the N‐terminal regions of the B870α,β and of reaction center L polypeptides on the cytoplasmic surface of the chromatophores of Rhodopseudomonas capsulata

Tadros¹,

Frank²,

Drews³

1986

FEBS Letters

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Chromatophores (intracytoplasmic inside-out membrane vesicles) from the mutant strain Ala+ of Rhodopseudomonas capsulata were treated with proteinase K in order to determine the orientation of the pigmentbinding polypeptides of the photochemical reaction center and of the light-harvesting complex B870. Nine amino acid residues of the B870a polypeptide were cleaved up to position Let&Vali" of the N-terminus and 22 residues up to position VaP-Tyrz3 of the p-chain N-terminus. From the reaction center L-chain the N-terminus up to position 27 (Val) was split off. The C-termini of the B870a and B polypeptides including the hydrophobic a-helical transmembrane portion remained intact. It is concluded that the N-terminal region of the pigment-binding polypeptides a and /I of the B870 light-harvesting complex and of the L-chain of the reaction center point to the cytoplasm while the C-termini of the B870a$ polypeptides are exposed or pointing toward the periplasmic membrane surface.

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“…In each LH complex, two different polypeptides bind noncovalently two or three bacteriochlorophyll and one or two carotenoid molecules. The axes of the pigment molecules have a strict orientation relative to the plane of the membrane (6,18,25). The pigment-binding polypeptides span the membrane once by a transmembrane a helix of hydrophobic amino acyl residues in LH complexes (5).…”

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confidence: 99%

Localization of reaction center and B800-850 antenna pigment proteins in membranes of Rhodobacter sphaeroides

et al. 1988

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The localization of the N-and C-terminal regions of pigment-binding polypeptides of the bacterial photosynthetic apparatus of Rhodobacter sphaeroides was investigated by proteinase K treatment of chromatophore and spheroplast-derived vesicles and amino acid sequence determination. Under conditions of proteinase K treatment of chromatophores, which left the in vivo absorption spectrum and the membrane intact, 15 and 46 amino acyl residues from the N-terminal regions of the L and M subunits, respectively, of the reaction center polypeptides were removed. The N termini are therefore exposed on the cytoplasmic surface of the membrane. The C-terminal domain of the light-harvesting B800-850a and B870a polypeptides was found to be exposed on the periplasmic surface of the membrane. A total of 9 and 13 amino acyl residues were cleaved from the B800-850a and B870a polypeptides, respectively, when spheroplasts were treated with proteinase K. The N-terminal regions of the a polypeptides were not digested in either membrane preparation and were apparently protected from proteolytic attack. Seven N-terminal amino acyl residues of the B800-850,1 polypeptide were removed after the digestion of chromatophores. C-terminal residues were not removed after the digestion of chromatophores or spheroplasts. The C termini seem to be protected from protease attack by interaction with the membrane. Therefore, the N-terminal regions of the , polypeptides are exposed on the cytoplasmic membrane surface. The C termini of the B polypeptides are believed to point to the periplasmic space.The photosynthetic apparatus of Rhodobacter sphaeroides is located in an intracytoplasmic membrane system formed by invaginations of the cytoplasmic membrane (15). The major components of the photosynthetic apparatus are the light-harvesting (LH) or antenna pigment-protein complexes and the photochemical reaction center (RC), which are present as integral membrane particles (14). The absorption of light energy by LH complexes creates excited singlet states which migrate over the antennae downhill to the RC where they are trapped and converted into a membrane potential difference and a redox potential difference. This conversion drives a cyclic electron transport and the formation of a proton gradient across the membrane (16).The bacteriochlorophyll and carotenoid pigments are bound in stoichiometric ratios to the polypeptides of the three complexes: RC and the LH complexes B870 and B800-850, named according to their near-infrared absorption bands. In each LH complex, two different polypeptides bind noncovalently two or three bacteriochlorophyll and one or two carotenoid molecules. The axes of the pigment molecules have a strict orientation relative to the plane of the membrane (6, 18, 25). The pigment-binding polypeptides span the membrane once by a transmembrane a helix of hydrophobic amino acyl residues in LH complexes (5). The RC subunits M and L (RC-M and RC-L, respectively) span the membrane five times each (1,13,22,39). The N-and C-terminal domains of L...

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Structures of antenna complexes of several Rhodospirillales from their resonance Raman spectra

Cited by 128 publications

References 16 publications

Modification of a hydrogen bond to a bacteriochlorophyll a molecule in the light-harvesting 1 antenna of Rhodobacter sphaeroides.

Modification of a hydrogen bond to a bacteriochlorophyll a molecule in the light-harvesting 1 antenna of Rhodobacter sphaeroides.

Localization of the N‐terminal regions of the B870α,β and of reaction center L polypeptides on the cytoplasmic surface of the chromatophores of Rhodopseudomonas capsulata

Localization of reaction center and B800-850 antenna pigment proteins in membranes of Rhodobacter sphaeroides

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