Light is one of the most important environmental factors in plants. Plants perceive changes of wavelength, duration, direction, and intensity of light. This information is first recognized by photoreceptors such as phytochromes and cryptochromes and is then passed through a series of signal cascades to evoke the physiological and developmental responses.

While the structure and function of the photoreceptors are relatively well understood through extensive biochemical and molecular biological studies, knowledge on the signaling components remains scarce. Furthermore, most study on the light signaling system in plants has been performed through genetic and molecular biological approaches, with no protein level approach having thus far been attempted.?We therefore plan to identify new light signaling components through a proteomic approach and study the biochemical properties of the phytochromes.

- Study the interactions between chromophore and apophytochrome residues using site-directed mutagenesis and photochromic effects.
- Study the Pfr specific degradation of phytochrome A with relation to ubiquitin-associated 26S proteasome pathway.
- Study the phosphorylation of phytochrome A N-terminal serine rich domain to determine the repressor which binds the phosphorylated phytochrome A and represses the phytochrome A activity.
- Study the light signal transduction pathway using MALDI-TOF mass spectrometry.

1. Cho JI, Ryoo NY, Eom JS, Lee DW, Kim HB, Jeong SW, Lee YH, Kwon YK, Cho MH, Bhoo SH, Hahn TR, Park YI, Hwang ID, Sheen J, Jeon JS (2009) Role of the rice hexokinases OsHXK5 and OsHXK6 as glucose sensors. Plant Physiol. 149:745-759

2. Lim HM, Cho MH, Jeon JS, Bhoo SH, Kwon YK, Hahn TR (2009) Altered Expression of pyrophosphate: Fructose-6-phosphate 1-phosphotransferase affects the growth of transgenic Arabidopsis plants. Mol. Cells. 27:641-649

3. Shin DH, Kim TL, Kwon YK, Cho MH, Yoo JH, Jeon JS, Hahn TR, Bhoo SH (2009) Characterization of Arabidopsis RopGEF family genes in response to abiotic stresses. Plant Biotechnol. Rep. 3:183-190

4. Jang HK, Cho MH, Kwon YK, Bhoo SH, Jeon JS, Hahn TR (2008) Roles of the residues Lys115 and Tyr116 in the binding of an allosteric inhibitor AMP ti Pea cytosolic fructose-1,6-bisphosphatase. Appl. Biol. Chem. 51(2):45-49

5. Yoon JM, Hahn TR, Cho MH, Jeon JS, Bhoo SH, Kwon YK (2008) The PHY domain is required for conformational stability and spectral integrity of the bacteriophytochrome from Deinococcus radiodurans. BBRC. 369:1120-1124

6. Cho JH, Hwang HY, Cho MH, Kwon YK, Jeon JS, Bhoo SH, Hahn TR (2008) The effecr of DTT in protein preparation for proteomic analysis: Remival of a highly abundant plant enzyme, rebulose bisphosphate carboxylase/oxygenase. J. of Plant Biol. 51(4):297-301

7. Jung JH, Seo DH, Bhoo SH, Ha SJ, Kim JS, Kim JH, Kwon DY, Cha JH, Park CS (2008) USe of restriction fragment length polymorphism analysis to differentiate fungal strains in Sunchang Meju. Food Sci. Biotechnol. 17(4):888-891

8. Phee BK, Kim JI, Shin DH, Yoo JH, Park KJ, Han YJ, Kwon YK, Cho MH, Jeon JS, Bhoo SH, Hahn TR (2008) A novel protein phosphatase indirectly regulates phytochrome-interacting factor 3 via phytochrome. Biochem. J. 415:247-255

9. Lee SK, Jeon JS, Bornke F, Voll L, Cho JI, Goh CH, Jeong SW, Park YL, Kim SJ, Choi SB, Miyao A, Hirovhika H, An GH, Cho MH, Bhoo SH, Sonnewald U, Hahn TR (2008) Loss of cytosolic fructose-1,6-bisphosphatase limits photosynthetic sucrose synthesis and causes severe growth retardations in rice(Oryza sativa). Plant, cell and environment, 31:1851-1863

10. Park SJ, Cho MH, Bhoo SH, Jeon JS, Kwon YK, Hahn TR (2007) Altered sucroes synthesis in rice plants with reduced activity of fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase. J. of plant biol. 50(1):38-43

11. Phee BK, Park SB, Cho JH, Jeon JS, Bhoo SH, Hahn TR (2007) Comparative proteomis analysis of blue lighr signaling components in the arabidopsis cryptochrome 1 mutant. Mol. Cells. 23(2):154-60

12. Lim HM, Cho JI, Lee SC, Cho MH, Bhoo SH, An GH, Hahn TR, Jeon JS (2007) Identification of a 20-bp regulatory element of the Arabidopsis pyrophosphate: fructose-6-phosphate 1-phosphotransferase α2 gene that is essential for expression. Plant cell Rep. 26:683-692

13. Ryoo NY, Yu C, Park CS, Baik MY, Park IM, Cho MH, Bhoo SH, An GH, Hahn TR, Jeon JS (2007) Knockout of a starch synthase gene OsSSIIIa/Flo5 causes white-core floury endosperm in rice(Oryza sativa L.). Plant cell Rep. 26:1083-1095

14. Lee SK, Hwang SK, Han MH, Eom JS, Kang HK, Han YY, Choi SB, Cho MH, Bhoo SH, An GH, Hahn TR, Okita T. Jeon JS (2007) Identification of the ADP-glucose pyrophosphorylase isoforms essential for starch synthesis in the leaf and seed endosperm of rice(Oryza sativa L.). Plant Mol. Biol. 65:531-546

15. Seo HS, Bhoo SH (2006) Photochromism of phytochromes and Cph1 requires critical amino acids and secondary structure in the N-terminal domain. J. of Microbiol. and Biotechnol. 16(9): 1441-1447

16. Kim JI, Bhoo SH, Han YJ, Zarate X, Furuya M, Song PS (2006) The PAS domain is required for dimerization of phytochrome A. J. of Photochemistry and Photobiology A: Chemistry 178:115-121.

17. Phee BK, Shin DH, Cho JH, Kim SH, Kim JI, Lee YH, Jeon JS, Bhoo SH, Hahn TR (2006) Identification of phytochrome-interacting protein candidates in Arabidopsis thaliana by co-immunoprecipitation coupled with MALDI-TOF MS. Proteomics. 6:3671-3680.

18. Phee BK, Cho JH, Park S, Jung JH, Lee YH, Jeon JS, Bhoo SH, Hahn TR (2004) Proteomic analysis of the response of Arabidopsis chloroplast proteins to high light stress. Proteomics 4:3560-3568.

19. Davis S, Bhoo SH, Durski A, Walker J, Vierstra R (2001) The heme oxygenase family required for phytochrome chromophore biosynthesis is mecessary for proper photomorphogenesis in higher plants. Plant Physiol. 126:656-669.

20. Bhoo SH, Davis S, Walker J, Kaniol B, Vierstra R (2001) Bacteriophytochromes are photochromic histidine kinase using biliverdin chromphore. Nature 414: 776-779.