Comparison of Structural Subunits of the Core Light-Harvesting Complexes of Photosynthetic Bacteria

Loach, Paul A.; Parkes-Loach, Pamela S.; Chang, Mu‐Chieh; Heller, Barbara A.; Bustamante, Peggy L.; Michalski, T. J.

doi:10.1007/978-1-4757-0893-6_27

Cited by 6 publications

(12 citation statements)

References 4 publications

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“…A functional B875-type complex, however, could be reconstituted only by addition of the LHI ao protein (37). In vivo, no B875 complex was formed when the LHI ao polypeptide was not synthesized (43).…”

Section: Discussionmentioning

confidence: 97%

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Characterization of LHI- and LHI+ Rhodobacter capsulatus pufA mutants

1992

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The NH2 termini of light-harvesting complex I (LHI) polypeptides a and ,B of Rhodobacter caus are thought to be involved in the assembly of the LHI complex. For a more detailed study of the role of the NH2-terminal segment of the LHI a protein in insertion into the intracytoplasmic membrane (ICM) of R. ca,psulaus, amino acids 6 to 8, 9 to 11, 12 and 13, or The LHI a and 1 polypeptides are present in a 1:1 ratio. The LHI apoproteins are integral proteins of the intracytoplasmic membrane (ICM) and span the membrane once with * Corresponding author. a central hydrophobic domain (51-53). The NH2 terminus of the LHI a polypeptide is located in the cytoplasm and has a short hydrophobic central part of amino acid residues flanked by positively charged residues which are next to a conserved proline (51, 52). The LHI a protein is inserted into the ICM in wild-type amounts only in the presence of the LHI 1 protein (43). The LHI 1 protein, however, has a negatively charged NH2 terminus and is able to integrate temporarily into the membrane in the absence of the LHI a protein (43). The LHI 13 protein was observed to be inserted earlier into the ICM than was the LHI a protein (43).The described structures and features of the LHI a and 1 polypeptides are conserved among several species of the genus Rhodospirillaceae (50). Two highly conserved amino acid residues (Trp-8 and Pro-13) are present in the NH2 terminus of the LHI a polypeptide (50). The aromatic structure of the Trp at position 8 seems to be of importance for the insertion of the LHI a polypeptide into the ICM (42). The conservative amino acid residue Pro-13, however, seems to be necessary for keeping the LHI 1 partner polypeptide in the membrane (42).Deletions or insertions have been introduced into the NH2 terminus of the LHI a protein to obtain more information on the structural requirements for the membrane insertion of the LHI a protein and the assembly of both LHI proteins into a functional complex. The construction and characterization of R capsulatus LHI-strains containing a mutated LHI a polypeptide are described in this report. Additionally, LHI+ revertant strains of one LHI-mutant strain are characterized.3030

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Section: Discussionmentioning

confidence: 97%

“…It has been reported that separately isolated LHI ,3 polypeptides but not LHI a polypeptides are able to form in vitro with Bchl a molecules the structural subunit (B820-like complex) of the B875 (LHI) complex (37). A functional B875-type complex, however, could be reconstituted only by addition of the LHI ao protein (37).…”

Section: Discussionmentioning

confidence: 99%

Characterization of LHI- and LHI+ Rhodobacter capsulatus pufA mutants

1992

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“…Isolation of a structural subunit, B820, from the LH1 complex has been previously reported for each of three different bacteria, R. rubrum (Loach et al 1985;Miller et al 1987), Rb. sphaeroides (Chang et al 1990b) and Rb.…”

Section: Reconstitution Systems With Homologous A-and T3-polypeptidesmentioning

confidence: 99%

“…It is possible to reversibly dissociate LH1 complexes into a subunit form (B820) and then to reversibly dissociate these subunits into the individual polypeptides and BChl (Loach et al 1985;Miller et al 1987;Parkes-Loach et al 1988;Loach et al 1989). Several recent studies confirm the ubiquity of a B820-type subunit in LH1 complexes of photosynthetic bacteria (Ghosh et al 1988;Visschers et al 1992;Meckenstock et al 1992;Jirsakova et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Probing protein structural requirements for formation of the core light-harvesting complex of photosynthetic bacteria using hybrid reconstitution methodology

et al. 1994

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The α- and β-polypeptides of LH1 isolated from four different photosynthetic bacteria (Rhodospirillum rubrum, Rhodobacter sphaeroides, Rhodobacter capsulatus and Rhodopseudomonas viridis) were used for homologous and hybrid reconstitution experiments with bacteriochlorophyll a. Formation of B820-type subunit complexes and LH1-type complexes were evaluated. The β-polypeptides of R. rubrum, Rb. sphaeroides and Rb. capsulatus behaved similarly and formed B820-type subunit complexes in the absence of an α-polypeptide. The α- and β-polypeptides were both required to form a LH1-type complex with each of these three homologous systems. In hybrid experiments where the β-polypeptides were tested for reconstitution with α-polypeptides other than their homologous partners, half of the twelve possible combinations resulted in formation of both B820- and LH1-type complexes. Three of the combinations that did not result in formation of a LH1-type complex involved the β-polypeptide of R. rubrum. It is suggested that these latter results can be explained by charge repulsion between the Lys at position-17 (assigning the conserved His located nearest to the C-terminus as position 0) in the β-polypeptide of R. rubrum and each of the heterologous α-polypeptides tested, all of which have an Arg at this location. Conclusions that can be derived from these experimental results include: (1) the experimental data support the idea that a central core region of approximately 40 amino acids exists in each of the polypeptides, which contains sufficient information to allow formation of both the B820- and LH1-type complexes and (2) a specific portion of the N-terminal hydrophilic region of each polypeptide was found in which ion pairs between oppositely charged groups on the α- and β-polypeptides seem to stabilize complex formation.

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“…Such an arrangement might lead to the formation of antenna complexes with different absorption characteristics. For instance Loach et al [37] With reference to the structural heterogenity of the peripheral antenna [18], it was recently reported that four a (designated a1-a4) and three p v1-p3) polypeptides were isolated and sequenced from R. palustris strain 2.6.1 [3]. The sequences of the PI, /I2 and p3 polypeptides were identical to the /la, pb (or pe) and pd sequences deduced from their coding regions.…”

Section: Northern-blot Analysismentioning

confidence: 99%

Cloning of a new antenna gene cluster and expression analysis of the antenna gene family of Rhodopseudomonas palustris

Tadros

Katsiou

Hoon

et al. 1993

European Journal of Biochemistry

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The genome of Rhodopseudomonas palustris contains five antenna gene clusters, αβa, αβb, αβc, αβd and αβe, which encode the light‐harvesting peripheral antenna complex II polypeptides. The isolation and characterisation of the gene which encodes the αe and βe polypeptides are reported. The primary structure of the βe polypeptide is identical to that of βb whilst the structure of αe is different from the other α subunits so far characterised. All five of the gene clusters were transcribed under high‐light conditions while under low‐light conditions only three were transcribed (αβb, αβd and αβe). Furthermore, Northern‐blot analysis showed that the gene clusters encode RNA transcripts of either 500 or 650 nucleotides. Individual members of the gene family showed a differential response in terms of the regulation of abundance of mRNA upon growth under either high‐light or low‐light intensities. Possible promoter sequences and operator sites upstream of the αβb, αβd and αβe genes were located. Furthermore using puc‐lacZ fusions in trans in R. palustris, we were able to examine the positions of the promoter of the gene clusters. The significance of these observations with respect to the regulation, organization and role of the peripheral antenna is discussed.

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Comparison of Structural Subunits of the Core Light-Harvesting Complexes of Photosynthetic Bacteria

Cited by 6 publications

References 4 publications

Characterization of LHI- and LHI+ Rhodobacter capsulatus pufA mutants

Characterization of LHI- and LHI+ Rhodobacter capsulatus pufA mutants

Probing protein structural requirements for formation of the core light-harvesting complex of photosynthetic bacteria using hybrid reconstitution methodology

Cloning of a new antenna gene cluster and expression analysis of the antenna gene family of Rhodopseudomonas palustris

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