Expression of a dominant negative form of cpSRP54 inhibits chloroplast biogenesis in <i>Arabidopsis</i>

Pilgrim, Marsha; Va, Klaas‐Jan; Wijk,; Parry, Devin H.; Sy, Donna A. C.; Hoffman, Neil E.

doi:10.1046/j.1365-313x.1998.00021.x

Cited by 64 publications

(81 citation statements)

References 41 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alternatively, deviations in the L18 region of these cab proteins may be an indication that they do not require cpSRP for localization. The latter is consistent with the ability of mutants lacking cpSRP54 or cpSRP43 to still accumulate cab proteins, albeit at reduced levels (8,23).…”

Section: Discussionsupporting

confidence: 82%

A novel precursor recognition element facilitates posttranslational binding to the signal recognition particle in chloroplasts

DeLille

Peterson

Johnson

et al. 2000

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

117

View full text Add to dashboard Cite

Signal recognition particles (SRPs) in the cytosols of prokaryotes and eukaryotes are used to target proteins to cytoplasmic membranes and the endoplasmic reticulum, respectively. The mechanism of targeting relies on cotranslational SRP binding to hydrophobic signal sequences. An organellar SRP identified in chloroplasts (cpSRP) is unusual in that it functions posttranslationally to localize a subset of nuclear-encoded thylakoid proteins. In assays that reconstitute thylakoid integration of the light harvesting chlorophyll-binding protein (LHCP), stromal cpSRP binds LHCP posttranslationally to form a cpSRP͞LHCP transit complex, which is believed to represent the LHCP form targeted to thylakoids. In this investigation, we have identified an 18-aa sequence motif in LHCP (L18) that, along with a hydrophobic domain, is required for transit complex formation. Fusion of L18 to the amino terminus of an endoplasmic reticulum-targeted protein, preprolactin, led to transit complex formation whereas wild-type preprolactin exhibited no ability to form a transit complex. In addition, a synthetic L18 peptide, which competed with LHCP for transit complex formation, caused a parallel inhibition of LHCP integration. Translocation of proteins by the thylakoid Sec and Delta pH transport systems was unaffected by the highest concentration of L18 peptide examined. Our data indicate that a motif contained in L18 functions in precursor recruitment to the posttranslational SRP pathway, one of at least four different thylakoid sorting pathways used by chloroplasts. Signal recognition particle (SRP) and its receptor comprise essential components of a signal peptide-based protein targeting mechanism that is conserved across evolutionary boundaries (1-3). SRPs in the cytosols of eukaryotes and Escherichia coli target proteins cotranslationally to the endoplasmic reticulum and cytoplasmic membrane, respectively. Targeting is initiated as a result of SRP binding to the hydrophobic domain of amino-terminal signal peptides or signal anchors as they emerge from the ribosome. The entire ribosome͞nascent polypeptide chain complex (RNC) then is piloted by SRP to an SRP receptor that functions at the membrane. GTP binding and hydrolysis by SRP and its receptor result in both the release of SRP from its receptor and the release of SRP from the RNC, whereupon the nascent chain enters a translocation pore that directs the translating polypeptide into or across the lipid bilayer.An organellar SRP, which exhibits striking structural and functional differences from cytosolic SRPs, also has been identified in chloroplasts (4, 5). Chloroplast SRP (cpSRP) is a soluble Ϸ200-kDa stromal particle that contains an evolutionary conserved 54-kDa subunit (cpSRP54) as well as a unique 43-kDa polypeptide (cpSRP43) (6). Unlike cytosolic SRPs, an RNA moiety is conspicuously lacking in cpSRP. Biochemical and genetic evidence have demonstrated that cpSRP functions posttranslationally to localize a subset of nuclear-encoded thylakoid proteins belonging to the chlorophyll...

show abstract

Section: Discussionsupporting

confidence: 82%

A novel precursor recognition element facilitates posttranslational binding to the signal recognition particle in chloroplasts

DeLille

Peterson

Johnson

et al. 2000

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

117

View full text Add to dashboard Cite

show abstract

“…a dominant negative mutation (Pilgrim et al, 1998). Surprisingly, these mutants have a phenotype different from that of chaos.…”

Section: Discussionmentioning

confidence: 99%

“…The bound protein was eluted by the addition of 200 L of 2 ϫ sample buffer and heated for 3 min at 95ЊC. Corresponding amounts of the diluted ribosome-free stroma, the supernatant, and the immunoprecipitate were separated by SDS-PAGE in 12% polyacrylamide gels, blotted onto nitrocellulose, and probed with the anti-chaos antiserum (1:5000), as described previously (Pilgrim et al, 1998).…”

Section: Immunoprecipitation Of the Signal Recognition Particle Complexmentioning

confidence: 99%

A Chromodomain Protein Encoded by the Arabidopsis CAO Gene Is a Plant-Specific Component of the Chloroplast Signal Recognition Particle Pathway That Is Involved in LHCP Targeting

et al. 1999

Self Cite

View full text Add to dashboard Cite

A recessive mutation in Arabidopsis, named chaos (for chlorophyll a/b binding protein harvesting-organelle specific; designated gene symbol CAO ), was isolated by using transposon tagging. Characterization of the phenotype of the chaos mutant revealed a specific reduction of pigment binding antenna proteins in the thylakoid membrane. These nuclear-encoded proteins utilize a chloroplast signal recognition particle (cpSRP) system to reach the thylakoid membrane. Both prokaryotes and eukaryotes possess a cytoplasmic SRP containing a 54-kD protein (SRP54) and an RNA. In chloroplasts, the homolog of SRP54 was found to bind a 43-kD protein (cpSRP43) rather than to an RNA. We cloned the CAO gene, which encodes a protein identified as Arabidopsis cpSRP43. The product of the CAO gene does not resemble any protein in the databases, although it contains motifs that are known to mediate protein-protein interactions. These motifs include ankyrin repeats and chromodomains. Therefore, CAO encodes an SRP component that is unique to plants. Surprisingly, the phenotype of the cpSRP43 mutant (i.e., chaos ) differs from that of the Arabidopsis cpSRP54 mutant, suggesting that the functions of the two proteins do not strictly overlap. This difference also suggests that the function of cpSRP43 is most likely restricted to protein targeting into the thylakoid membrane, whereas cpSRP54 may be involved in an additional process(es), such as chloroplast biogenesis, perhaps through chloroplast-ribosomal association with chloroplast ribosomes. INTRODUCTIONHigher plants require chloroplasts for essential functions ranging from photosynthesis to sugar, lipid, and amino acid biosyntheses. Many of the proteins required for the light reactions of photosynthesis, including the chlorophyll-containing antenna proteins, are localized in the thylakoid membrane. Thylakoid proteins are encoded by both the nuclear and chloroplast genomes. Nuclear-encoded proteins destined for the thylakoid membrane are synthesized with a cleavable N-terminal extension (transit peptide) that targets the protein across the envelope membranes into the stroma (reviewed in Cline and Henry, 1996;Kermode, 1996;Lübeck et al., 1997). Multiple mechanisms exist for targeting proteins from the stroma to the thylakoid membrane (reviewed in Cline and Henry, 1996;Klösgen, 1997). These include spontaneous insertion, a chloroplast Sec r -dependent pathway, a chloroplast signal recognition particle (cpSRP) pathway, and a pathway requiring only an electrochemical potential of ⌬ pH across the thylakoid membrane. These pathways can be distinguished by specific requirements for stromal proteins and/or by energetic requirements when in 1 These authors contributed equally to this work. 2 To whom correspondence should be addressed: E-mail lnussaume @cea.fr; fax 33-442-25-4656. 88The Plant Cell vitro reconstitution assays are performed. In vitro, precursor proteins are targeted exclusively via one of the aforementioned pathways.LHCIIb proteins are the most abundant of the thylakoid membrane ...

show abstract

“…In addition to regulatory genes, genetic studies have identi®ed nuclear genes whose products are imported into chloroplasts and whose functions are required for plastid biogenesis. These proteins include those that participate in the import of proteins into the chloroplast such as PPI1 (Jarvis et al, 1998) and PPI2 (Bauer et al, 2000), in protein targeting and routing, such as CAO (Pilgrim et al, 1998), FFC (Voelker and Barkan, 1995), THA1 (Voelker et al, 1997), CSY1 (Roy and Barkan, 1998), and HCF106 (Klimyuk et al, 1999), and in protein folding such as VAR2 and SLP (Apuya et al, 2001). They also include enzymes catalyzing the biosynthesis of chlorophyll (GUN5) (Nobuyoshi et al, 2001) and isoprenoids such as CLA (Amin et al, 1999;Estevez et al, 2000) and IM (Carol et al, 1999;Wu et al, 1999), proteins involved in plastid gene transcription and translation such as PAC (Meurer et al, 1998) and ALBOSTRIANS (Hess et al, 1994), and metabolite transporters CUE1 (Streat®eld et al, 1999) and LAF6 (Moller et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

et al. 2003

View full text Add to dashboard Cite

SummaryThe cr88 mutant of Arabidopsis is a novel chlorate-resistant mutant that displays long hypocotyls in red light, but not in far red or blue light, and is delayed in the greening process. In cotyledons and young leaves, plastids are less developed compared with those of the wild type. In addition, a subset of light-regulated genes are under-expressed in this mutant. To understand the pleiotropic phenotypes of cr88, we isolated the CR88 gene through map-based cloning. We found that CR88 encodes a chloroplast-targeted 90-kDa heat shock protein (HSP90). The CR88 gene is expressed at highest levels during early post-germination stages and in leaves and reproductive organs. It is constitutively expressed but is also light and heat shock inducible. Chloroplast import experiments showed that the protein is localized to the stroma compartment of the chloroplast. The possible function of an HSP90 in the chloroplast and a plausible explanation of the pleiotropic phenotypes observed in cr88 are discussed.

show abstract

Expression of a dominant negative form of cpSRP54 inhibits chloroplast biogenesis in Arabidopsis

Cited by 64 publications

References 41 publications

A novel precursor recognition element facilitates posttranslational binding to the signal recognition particle in chloroplasts

A novel precursor recognition element facilitates posttranslational binding to the signal recognition particle in chloroplasts

A Chromodomain Protein Encoded by the Arabidopsis CAO Gene Is a Plant-Specific Component of the Chloroplast Signal Recognition Particle Pathway That Is Involved in LHCP Targeting

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

Contact Info

Product

Resources

About