• Journal of Plant Biology
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• v.33 no.1
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• pp.81-84
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• 1990

The chloroplast has been the prime light-energy harvesting organelle on earth. It also carries out several key metabolic processes, such as lipid synthesis and nitrogen metabolism. Even though the chloroplast has its own genome, its coding capacity can afford only dozens of proteins, and most of the proteins functioning in the chloroplast are imported from the cytosol where nuclear encoded chloroplast genes are synthesized on free cytosokic ribosomes. Precursor proteins synthesized on cytosolic ribosomes have transit peptides at the amino termini of the proteins, and the transit peptide is sufficient to transfer chloroplast proteins from the cytosol into the chloroplast. When comparing amino acid sequences duduced from the nucleotide sequences of the clones of the chloroplast proteins, high homologies can be found among the transit peptides of proteins with the same function. Overall amino acid compositions of the transit peptides show amphiphilic characters of the transit peptides, and the amphiphilicity indicates that three dimensional structure of the transit peptide is responsible for the translocation of the chloroplast proteins.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.28-38
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• 2023

Plant viruses are responsible for worldwide production losses of numerous economically important crops. The most common plant RNA viruses are positivesense single-stranded RNA viruses [(+)ss RNA viruses]. These viruses have small genomes that encode a limited number of proteins. The viruses depend on their host's machinery for the replication of their RNA genome, assembly, movement, and attraction to the vectors for dispersal. Recently researchers have reported that chloroplast proteins are crucial for replicating (+)ss plant RNA viruses. Some chloroplast proteins, including translation initiation factor [eIF(iso)4E] and 75 DEAD-box RNA helicase RH8, help viruses fulfill their infection cycle in plants. In contrast, other chloroplast proteins such as PAP2.1, PSaC, and ATPsyn-α play active roles in plant defense against viruses. This is also consistent with the idea that reactive oxygen species, salicylic acid, jasmonic acid, and abscisic acid are produced in chloroplast. However, knowledge of molecular mechanisms and functions underlying these chloroplast host factors during the virus infection is still scarce and remains largely unknown. Our review briefly summarizes the latest knowledge regarding the possible role of chloroplast in plant virus replication, emphasizing chloroplast-related proteins. We have highlighted current advances regarding chloroplast-related proteins' role in replicating plant (+)ss RNA viruses.

• Journal of Ginseng Research
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• v.19 no.3
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• pp.275-280
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• 1995

The formation of thylakoid membrane proteins and changes in the chloroplast ultrastructure of ginseng leaf were investigated as a function of time following the leaf emergence. The leaf chloroplast obtained just after the leaf emergence showed short rod-like thylakoids which were connected and arranged in 3~4 layers along the longitudinal axis of the chloroplast. The 10 DAE (days after emergence) chloroplast started to form grana structure. The typical grana structure was observed 17 DAE, and the grana was fully developed 28 DAE. The membrane proteins obtained from just after emerging leaf were separated into many minor bands indicating no CP-complex formation yet. LHC II was detected after 10 days. CP 47 and CP 43 were detected after 17 days. After 28 days, the PS I and PS II proteins were distinctly separated into CP 1, LHC II, CP 47, CP 43, CP 29, CP 27+24. Thus, the appearance of the light harvesting protein, LHC II, which was concentrated in grana stacks, was consis tent in time with the formation of grana stacks 17 DAE. Key words Chloroplast ultrastructure, grana, CP-complex, LHC II.

• Molecules and Cells
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• v.41 no.3
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• pp.161-167
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• 2018

Chloroplasts are present in organisms belonging to the kingdom Plantae. These organelles are thought to have originated from photosynthetic cyanobacteria through endosymbiosis. During endosymbiosis, most cyanobacterial genes were transferred to the host nucleus. Therefore, most chloroplast proteins became encoded in the nuclear genome and must return to the chloroplast after translation. The N-terminal cleavable transit peptide (TP) is necessary and sufficient for the import of nucleus-encoded interior chloroplast proteins. Over the past decade, extensive research on the TP has revealed many important characteristic features of TPs. These studies have also shed light on the question of how the many diverse TPs could have evolved to target specific proteins to the chloroplast. In this review, we summarize the characteristic features of TPs. We also highlight recent advances in our understanding of TP evolution and provide future perspectives about this important research area.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.2
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• pp.85-94
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• 2000

The effects of ozone on chloroplast development in barley seedlings during greening was investigated based on ultrastructural changes in the chloroplasts and band pattern changes in the chloroplast thylakoid membrane proteins. In this analysis of the chloroplast thylakoid membrane thylakoid protein band pattern by SDS-PAGE, none of the 24-hour greening bands included were clearer than the control. This means that the ozone treatment produced a dealy in chloroplast development and decreased the amount of thylakoid membrane proteins. LHC II chloroplast band of developing barley seedlings treated with 0.5 and 1.0 ppm ozone during the last 4 hours of the 24-hour greening period was weaker than the other bands. This result indicates that ozone affects the LHC II protein complex of the chloroplast thylakoid membrane. When investigating the ultastructural changes in ozone-treated chloroplast, the main site affected by 0.5 ppm ozone was the chloroplast grana, thereby explaining the delayed chloroplast development during the early phase of greening. In addition, there was also a structural change in the stromal grana of the ozone treated chloroplast during the middle phase of greening. The effects of ozone on the chloroplast of barley seedlings during the last phase of 48-hour greening were more functionally inhibiting than structural changes.

• BMB Reports
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• v.42 no.7
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• pp.450-455
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• 2009

The "stage albinism line of winter wheat" FA85 was a specific natural mutant strain on leaf color. This physiological mutation was controlled by cytogene. In order to reveal the genetic and biochemical mechanism of albinism, 2-DE was used to investigate the difference of chloroplast protein expression pattern between FA85 and its parent wheat Aibian 1. From the results of 2-DE gels analysis, approximately 683 spots were detected on each gel, and 57 spots were expressed differently at least two-fold. Using MALDI-TOF/TOF MS, 14 of 57 spots were identified, which could be categorized into four classes: carbon metabolism, energy metabolism, defense/stress response and signal transduction. Compared with the parent wheat, the expression of ATPase-$\gamma$ and GP1-$\alpha$ was up-regulated in FA85, and of other proteins was down-regulated. Together, we concluded that the expression of chloroplast proteins had changed obviously in FA85, which might be related to the leaf color mutant.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.310-316
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• 2001

To find out the effect of low temperature on the regulation of tomato chloroplast genes, the optimization of the system in chloroplast protein synthesis and the identification of the changes in chloroplast protein synthesis induced by chilling were studied. Incorporation reaction occurred rapidly at the first 30 minutes and was constantly maintained after 60 minutes. A broad optimal temperature on protein synthesis was found around 20 to $30^{\circ}C$. No difference was shown in the chloroplast protein synthesis under high light intensity (1600 ${\mu}E/m^2/s$) as well as under low light intensity (400 ${\mu}E/m^2/s$) even darkness. $K^+$, $Mg^{++}$ and ATP at an optimal concentration act as an activator, while DTT, chloramphenicol, cycloheximide, $Ca^{++}$ and inorganic phosphate act as an inhibitor in the chloroplast protein synthesis. Synthesis of 15, 55 and 60 kd chloroplast encoded stromal proteins and 18, 24, 33 and 55 kd chloroplast encoded thylakoid membrane proteins were reduced by chilling, while 17 kd chloroplast encoded stromal protein and 16 kd chloroplast encoded thylakoid membrane protein was induced by chilling. It was expected that the 55 kd stromal protein would be the large subunit of rubisco and the 33 kd thylakoid membrane protein would be the D1 protein which was drastically reduced by chilling.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.14-14
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• 2010

Plastid proteomics are essential organelles present in virtually all cells in plants and green algae. Plastids are responsible for the synthesis and storage of key molecules required for the basic architecture and functions of plant cells. The proteome of plastid, and in particular of chloroplast, have received significant amounts of attention in recent years. Various fractionation and mass spectrometry (MS) techniques have been applied to catalogue the chloroplast proteome and its sub-organelles compartments. To better understanding the function of the lumenal sub-organelles within the thylakoid network, we have carried out a systematical analysis and identification of the lumenal proteins in the thylakoid of wheat by using Tricine-SDS-PAGE, and LTQ-ESI-FTICR mass spectrometry followed by SWISS-PROT database searching. We isolation and fractionation these membrane from fully developed wheat leaves using a combination of differential and gradient centrifugation couple to high speed ultra-centrifuge. After collecting all proteins to eliminate possible same proteins, we estimated that there are 407 different proteins including chloroplast, chloroplast stroma, lumenal, and thylakoid membrane proteins excluding 20 proteins, which were identified in nucleus, cytoplasm and mitochondria. A combination of these three programs (PSORT, TargetP, TMHMM, and TOPPRED) was found to provide a useful tool for evaluating chloroplast localization, transit peptide, transmembranes, and also could reveal possible alternative processing sites and dual targeting. Finally, we report also sub-cellular location specific protein interaction network using Cytoscape software, which provides further insight into the biochemical pathways of photosynthesis. The present work helps understanding photosynthesis process in wheat at the molecular level and provides a new overview of the biochemical machinery of the thylakoid in wheat.

• Journal of Plant Biotechnology
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• v.37 no.3
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• pp.275-282
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• 2010

Chloroplast transformation in higher plants offers many attractive advantages over nuclear transformation, including a high-level accumulation of foreign proteins, multi-gene expression in single transformation event via transgene stacking in operons and no position effect due to site-specific integration of transgenes by homologous recombination. Most importantly, chloroplast transgenic plants are eco-friendly because their transgenes are maternally inheritance in most crop plants. However, chloroplast transformation system has limited success in crops alike nuclear transformation. In the past two decades, great progress has been made to overcome the limitations of chloroplast transformation, thus expending chloroplast bioreactor to several important crops including soybean, carrot, lettuce, and oilseed. Therefore, it has become possible that chloroplast transformation of crops can be used not only for the improvement of agronomic traits, but also for the production of vaccines and high valuable therapeutic proteins in pharmaceutical industry.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.57-62
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• 1999

Light-regulated translation of chloroplast mRNAs requires nuclear-encoded trans-acting factors that interact with the 5' untranslated region (UTR) of these mRNAs. A set of four proteins (60, 55, 47, and 38 kDa) that bind to the 5'-UTR of the psbA mRNA had been identified in C. reinhardtii. 47 kDa protein (RB47) was found to encode a chloroplast poly (A)-binding protein (cPABP) that specifically binds to the 5'-UTR of the psbA mRNA, and essential for translation of this mRNA, cDNA encoding 60 kDa protein (RB60) was isolated, and the amino acid sequence of the encoded protein was highly homologous to plants and mammalian protein disulfide isomerases (PDI), normally found in the endoplasmic reticulum (ER). Immunoblot analysis of C. reinhardtii proteins showed that anti-PDI recognized a distinct protein of 56 kDa in whole cell extract, whereas anti-rRB60 detected a 60 kDa protein. The ER-PDI was not retained on heparin-agarose resin whereas RB60 was retained. In vitro translation products of the RB60 cDNA can be transported into C. reinhardtii chloroplast in vitro. Immunoblot analysis of isolated pea chloroplasts indicated that higher plant also possess a RB60 homolog. In vitro RNA-binding studies showed that RB60 modulates the binding of cPABP to the 5'-UTR of the psbA mRNA by reversibly changing the redox status of cPABP using redox potential or ADP-dependent phosphorylation. Site-directed mutagenesis of -CGHC- catalytic site in thioredoxin-like domain of RB60 is an unique PDI located in the chloroplast of C. reinhardtii, and suggest that the chloroplast PDI may have evolved to utilize the redox-regulated thioredoxin like domain as a mechanism for regulating the light-activated translation of the psbA mRNA.