Poster: Photosynthesis

Abs # 315: Post-translational and transcriptional regulation of CND41 protease during senescence

Presenter:	Kato, Yusuke , yusuke21@kais.kyoto-u.ac.jp
Authors	Kato, Yusuke  (A)   Yamamoto, Yumiko  (A)   Sato, Fumihiko  (A)
Affiliations:	(A): Department of Plant Gene and Totipotency, Graduate School of Biostudies, Kyoto University
Web Site:	http://www.lif.kyoto-u.ac.jp/labs/callus/introduct/TOPE.htm

CND41 is a 41kDa DNA-binding protein isolated from chloroplast nucleoids of cultured tobacco cells. CND41 has active domain of aspartic protease and the purified protein had strong proteolytic activity at acidic pHs (pH2-4) (Murakami et al. FEBS Lett. 468:15(2000)). Further studies showed that CND41 could degrade denatured Rubisco at physiological pH and the expression increased with leaf age. Characterization of transgenic tobacco with low CND41 supported the functional involvement of CND41 in the in vivo degradation of Rubisco protein during senescence. In this study, we showed the possibilities of post-translational and transcriptional regulation of CND41 protease during senescence. Since aspartic proteases are very common in senescent plants, we prepared the specific antibodies against CND41-specific peptide (anti-Val 186 to Ser 206). These newly prepared antibodies reacted with CND41 specifically. Immuno-blot analysis of leaves clearly indicated that CND41 has been processed differently during maturation of leaves in whole plants; young leaves contained more processed low molecular weight bands and senescent leaves showed mature size of CND41, suggesting that CND41 was only active in senescent leaves. Further study in seedlings also suggested the induction of CND41 accumulation by the senescence induced by the combined treatment of nitrogen-starvation, high sucrose and darkness. Further characterization of CND41 expression and its post-translational regulation is on going.