Role of apparent membrane growth initiation sites during photosynthetic membrane development in synchronously dividing Rhodopseudomonas sphaeroides

Reilly, Patricia A.; Niederman, Robert A.

doi:10.1128/jb.167.1.153-159.1986

Cited by 28 publications

(17 citation statements)

References 24 publications

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“…xw!y synthesized I3875 reactior! center cores of rhe photosynthetic apparatus predominantly incorporate into a distinct cytoplasmic membrane fraction from which they are then transferred into the ICM [28]. Dierstein et al [ 161 also found preferential integration of the reaction center polypeptides into a light, non-ICM membrane fraction in E. capsutatus.…”

Section: Discussionmentioning

confidence: 99%

Identification and solubilization of a signal peptidase from the phototrophic bacterium Rhodobacter capsulatus

1992

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In Gram-ncgativc bacteria, exported proteins arc synthesized with an amino-terminal signal sequence which is cleaved off by the signal peptidasc during, or shortly after the translocation process. Here, we report the identification and solubilization of a signal peptidase from the phototrophic k6cterium Ahc~uf~~cfe~ cupsularr~s which cleaves homologous and heierologous precursor proteins at the authentic cleavage site. This signal peptidase is the first identified component of the I?. cupsufuras protein export machinery.

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Section: Discussionmentioning

confidence: 99%

Identification and solubilization of a signal peptidase from the phototrophic bacterium Rhodobacter capsulatus

1992

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“…It has been proposed that the development of ICM is initiated by the incorporation of reaction centers and B875 complexes at specific sites into the peripheral cytoplasmic membrane (CM) (5,27,32). Some of the B800-850 complexes are added to these sites as well, but by far most of them become integrated into the developing ICM (27,28,32).…”

Section: Discussionmentioning

confidence: 99%

Regulation of tetrapyrrole synthesis by light in chemostat cultures of Rhodobacter sphaeroides

Oelze

1988

J Bacteriol

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Control of bacteriochlorophyll (Bchl), magnesium protoporp}yrin monomethyl ester (MgPME), cytochromes, and coproporphyrin by light was studied with chemostat cultures of Rhodobacter sphaeroides growing at a constant dilution rate. By increasing the growth-limiting light energy flux from 10 to 55 W/m2, specific Bchl contents decreased from 19.3 to 7.9 nmol/mg of protein. This was strictly proportional to a decrease in the ratio of B800-850 to B875 light-harvesting complexes. MgPME levels increased from 1.5 to 5.3 nmol/mg of protein, while cytochrome as well as coproporphyrin levels stayed constant at 0.46 and 1.95 nmol/mg of protein, respectively. Since in chemostat cultures steady-state levels of a product represent the rate of synthesis, these results infer only slight control of the rate-limiting step of total tetrapyrrol formation by light. In substrate-limited cultures MgPME was accumulated when growth and Bchl formation approached substrate saturation. This suggests that light controls a second step, i.e., MgPME conversion, whenever too much precursor is available, owing to the low sensitivity of the initial step of control. MgPME was preferentially localized in a subcellular fraction with high contents of B875 complexes. A second fraction exhibiting increased contents of B800-850 complexes lacked significant levels of MgPME. These results are discussed in terms of localization of Bchl synthesis in the membrane system of R. sphaeroides.

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“…This cell-free system now offers the opportunity to study integration and assembly of pigment-binding proteins in mutant membranes lacking individual pigment-binding proteins. Furthermore, it should be suitable to address the question of the specificity of the protein insertion into distinct membrane subfractions as suggested by others (7,29). These studies should shed some light on the complex regulation of synthesis, integration and assembly of the photosynthetic apparatus from R. capsulatus.…”

Section: Discussionmentioning

confidence: 99%

“…It was shown that (a) they appear to be inserted into distinct membrane areas (7,15,29); (b) the RC is not properly assembled if the B870 complex is missing (14); (c) pigments are required for the stability and proper assembly of the protein complexes (20).…”

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Development of a cell-free system to study the membrane assembly of photosynthetic proteins of Rhodobacter capsulatus.

Troschel

Müller

1990

The Journal of Cell Biology

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Abstract. A cell-free translation system from the facultatively photoheterotrophic bacterium Rhodobacter capsulatus is described. Synthesis of two proteins of the bacterium's photosynthetic apparatus (lightharvesting complex B870 ot and/~) was performed by SP6 polymerase transcription of the subcloned genes, isolation of the mRNA and translation in vitro using a cell-free extract of R. capsulatus cells.The integration of these proteins in vitro into added intracytoplasmic membrane vesicles (ICM) is demonstrated. Without addition of ICM ,,070% of the synthesized B870 proteins were soluble. If, however, ICM were present during synthesis, the majority of the soluble protein was found to associate with the membranes. The membrane-associated polypeptides could be solubilized only by detergent treatment but could not be extracted by treatment at alkaline pH (Na2CO3), suggesting that the proteins had been firmly inserted into the lipid bilayer. Moreover, the B870 t~ and proteins that integrated in vitro into ICM were also found to associate with pigment ligands and to assemble into a native reaction center/B870 complex. The native conformation of this complex isolated from ICM by Triton fractionation was demonstrated by microspectral analysis of the bound pigments.T HF. Gram-negative, facultatively photoheterotrophic bacterium Rhodobacter capsulatus is a good model organism for studying membrane differentiation because of its inducible apparatus for photosynthesis. The assembly of the photosynthetically active intracytoplasmic membrane (ICM) ~ system is induced by lowering either the oxygen tension or the light intensity (reviewed in references 9, 17, 40).The photosynthetic complexes are composed of eight different integral membrane proteins, organized into two light-harvesting (LH) complexes, B870 (LH-I) and B800-850 (LH-II), and a reaction center (RC). Each LH-complex consists of two pigment-binding proteins in a 1:1 stoichiometry; B870 t~ and/3 (Mr = 12 and 7 kD), and B800-850 ot and ~ (Mr = 10 and 8 kD). The B800-850 complex also contains the non-pigment-binding protein V (Mr = 14 kD). Each of these ot and/3 peptides has one et-helical transmembrane segment of • 20 amino acids with the NH2 terminus facing the cytoplasm and the COOH terminus located in the periplasmic space (32-34). The RC consists of the two pigment-binding proteins L and M (Mr = 20.5 and 24 kD), each possessing five membrane-spanning segments, and the non-pigment-binding protein H (Mr = 28 kD), which is anchored within the membrane by a single hydrophobic stretch. The three RC proteins are found in the ICM in a 1:1:1 stoichiometry with their NH2 termini located in the cyto-1. Abbreviations used in this paper: ICM, intracytoplasmic membrane vesicles; Me2SO, dimethyl sulfoxide; TeaOAc, triethanolamine acetate. plasm (34). None of the eight polypeptides is synthesized with a cleavable, NH2-terminal signal sequence (8).The genes for the eight proteins of the photosynthetic complexes are organized into three operons: puf(B870 a and ~, RC-L and M), puh ...

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Role of apparent membrane growth initiation sites during photosynthetic membrane development in synchronously dividing Rhodopseudomonas sphaeroides

Cited by 28 publications

References 24 publications

Identification and solubilization of a signal peptidase from the phototrophic bacterium Rhodobacter capsulatus

Identification and solubilization of a signal peptidase from the phototrophic bacterium Rhodobacter capsulatus

Regulation of tetrapyrrole synthesis by light in chemostat cultures of Rhodobacter sphaeroides

Development of a cell-free system to study the membrane assembly of photosynthetic proteins of Rhodobacter capsulatus.

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