Diatom Fucoxanthin Chlorophyll a/c-binding Protein (FCP) and Land Plant Light-harvesting Proteins Use a Similar Pathway for Thylakoid Membrane Insertion

Lang, Markus; Kroth, Peter G.

doi:10.1074/jbc.m006417200

Cited by 33 publications

(22 citation statements)

References 39 publications

(41 reference statements)

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“…Diatoms may contribute organic matter to sediments because they are encapsulated in high-density silica frustules that can rapidly transport OM to depth (Dunne et al, 2005; Ragueneau, et al, 2006; Miki et al, 2009). Multiple fucoxanthin chlorophyll a/c binding proteins (FCPs), important light harvesting complex proteins in diatoms and other marine algae (Grossman et al, 1995; Lang and Kroth, 2001; Nunn et al, 2009), were observed in all sediment samples. The presence of these proteins is not completely unexpected; FCPs are central in the light harvesting complex, representing the most abundant protein class discovered in mid-exponential growth T. pseudonana (Nunn et al, 2009) and later observed to remain after extensive microbial attack in a controlled month-long degradation experiment (Nunn et al, 2010) .…”

Section: Discussionmentioning

confidence: 99%

Identifying and tracking proteins through the marine water column: Insights into the inputs and preservation mechanisms of protein in sediments

Moore

Nunn

Goodlett

et al. 2012

Geochimica et Cosmochimica Acta

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Proteins generated during primary production represent an important fraction of marine organic nitrogen and carbon, and have the potential to provide organism-specific information in the environment. The Bering Sea is a highly productive system dominated by seasonal blooms and was used as a model system for algal proteins to be tracked through the water column and incorporated into detrital sedimentary material. Samples of suspended and sinking particles were collected at multiple depths along with surface sediments on the continental shelf and deeper basin of the Bering Sea. Modified standard proteomic preparations were used in conjunction with high pressure liquid chromatography-tandem mass spectrometry to identify the suite of proteins present and monitor changes in their distribution. In surface waters 207 proteins were identified, decreasing through the water column to 52 proteins identified in post-bloom shelf surface sediments and 24 proteins in deeper (3490 m) basin sediments. The vast majority of identified proteins in all samples were diatom in origin, reflecting their dominant contribution of biomass during the spring bloom. Identified proteins were predominantly from metabolic, binding/structural, and transport-related protein groups. Significant linear correlations were observed between the number of proteins identified and the concentration of total hydrolysable amino acids normalized to carbon and nitrogen. Organelle-bound, transmembrane, photosynthetic, and other proteins involved in light harvesting were preferentially retained during recycling. These findings suggest that organelle and membrane protection represent important mechanisms that enhance the preservation of protein during transport and incorporation into sediments.

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Section: Discussionmentioning

confidence: 99%

Identifying and tracking proteins through the marine water column: Insights into the inputs and preservation mechanisms of protein in sediments

Moore

Nunn

Goodlett

et al. 2012

Geochimica et Cosmochimica Acta

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“…It is conserved in all LHCPs (21) and also in fucoxanthin chlorophyll a / c -binding proteins of diatoms (39) that are also targeted by cpSRP. In LHCPs, the DPLG motif is part of a conserved interaction site for carotenoids (40), which are crucial for folding (41).…”

Section: Discussionmentioning

confidence: 99%

cpSRP43 Is a Novel Chaperone Specific for Light-harvesting Chlorophyll a,b-binding Proteins

Falk

Sinning

2010

Journal of Biological Chemistry

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The biosynthesis of most membrane proteins is directly coupled to membrane insertion, and therefore, molecular chaperones are not required. The light-harvesting chlorophyll a,b-binding proteins (LHCPs) present a prominent exception as they are synthesized in the cytoplasm, and after import into the chloroplast, they are targeted and inserted into the thylakoid membrane. Upon arrival in the stroma, LHCPs form a soluble transit complex with the chloroplast signal recognition particle (cpSRP) consisting of an SRP54 homolog and the unique cpSRP43 composed of three chromodomains and four ankyrin repeats. Here we describe that cpSRP43 alone prevents aggregation of LHCP by formation of a complex with nanomolar affinity, whereas cpSRP54 is not required for this chaperone activity. Other stromal chaperones like trigger factor cannot replace cpSRP43, which implies that LHCPs require a specific chaperone. Although cpSRP43 does not have an ATPase activity, it can dissolve aggregates of LHCPs similar to chaperones of the Hsp104/ClpB family. We show that the LHCP-cpSRP43 interaction is predominantly hydrophobic but strictly depends on an intact DPLG motif between the second and third transmembrane region. The cpSRP43 ankyrin repeats that provide the binding site for the DPLG motif are sufficient for the chaperone function, whereas the chromodomains are dispensable. Taken together, we define cpSRP43 as a highly specific chaperone for LHCPs in addition to its established function as a targeting factor for this family of membrane proteins.

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“…Proteins directed to these plastids possess bipartite targeting sequences, with an N-terminal signal sequence (24) that directs them to the chloroplast ER, where they are cotranslationally imported across the first membrane (4,7,30). The domain after the signal sequence is the predicted transit peptide for transport across the inner two membranes, in a process likely to resemble translocation across plant chloroplast envelopes (43).…”

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Analysis of Euglena gracilis Plastid-Targeted Proteins Reveals Different Classes of Transit Sequences

2006

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The plastid of Euglena gracilis was acquired secondarily through an endosymbiotic event with a eukaryotic green alga, and as a result, it is surrounded by a third membrane. This membrane complexity raises the question of how the plastid proteins are targeted to and imported into the organelle. To further explore plastid protein targeting in Euglena, we screened a total of 9,461 expressed sequence tag (EST) clusters (derived from 19,013 individual ESTs) for full-length proteins that are plastid localized to characterize their targeting sequences and to infer potential modes of translocation. Of the 117 proteins identified as being potentially plastid localized whose N-terminal targeting sequences could be inferred, 83 were unique and could be classified into two major groups. Class I proteins have tripartite targeting sequences, comprising (in order) an N-terminal signal sequence, a plastid transit peptide domain, and a predicted stop-transfer sequence. Within this class of proteins are the lumen-targeted proteins (class IB), which have an additional hydrophobic domain similar to a signal sequence and required for further targeting across the thylakoid membrane. Class II proteins lack the putative stop-transfer sequence and possess only a signal sequence at the N terminus, followed by what, in amino acid composition, resembles a plastid transit peptide. Unexpectedly, a few unrelated plastid-targeted proteins exhibit highly similar transit sequences, implying either a recent swapping of these domains or a conserved function. This work represents the most comprehensive description to date of transit peptides in Euglena and hints at the complex routes of plastid targeting that must exist in this organism.A fundamental problem in cell biology is the precise and efficient targeting of proteins synthesized by cytoplasmic ribosomes to their appropriate intracellular locations. Proteins destined for the endomembrane system, mitochondria, or the chloroplast usually have specific N-terminal targeting domains that are required for proper subcellular localization. These leader sequences are often removed by specific proteases at the protein's destination prior to it assuming its active conformation. For chloroplast-targeted proteins in plants and algae, an N-terminal transit peptide (TP) is both necessary and sufficient for correct plastid targeting (11). Transit peptides are not conserved in sequence but exhibit characteristic biochemical properties, such as an elevated content of the hydroxylated amino acids serine and threonine as well as a deficiency of acidic (aspartate and glutamate) amino acids (76). Within a typical chloroplast, there are six distinct locations to which the constituent proteins must be sorted, and some proteins have to cross up to three membranes (33). This complexity requires additional targeting information within the transit peptide, such as the signal sequence-like domain found in proteins targeted to the thylakoid membrane, or information contained within the mature portion of the protein itself...

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Diatom Fucoxanthin Chlorophyll a/c-binding Protein (FCP) and Land Plant Light-harvesting Proteins Use a Similar Pathway for Thylakoid Membrane Insertion

Cited by 33 publications

References 39 publications

Identifying and tracking proteins through the marine water column: Insights into the inputs and preservation mechanisms of protein in sediments

Identifying and tracking proteins through the marine water column: Insights into the inputs and preservation mechanisms of protein in sediments

cpSRP43 Is a Novel Chaperone Specific for Light-harvesting Chlorophyll a,b-binding Proteins

Analysis of Euglena gracilis Plastid-Targeted Proteins Reveals Different Classes of Transit Sequences

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