Loss of peripheral polypeptides in the stromal side of photosystem I by light-chilling in cucumber leaves.
Photosystem I (PSI) is severely damaged by chilling at 4 degrees C in low light, especially in the chilling sensitive plant cucumber. To investigate the early events in PSI photoinhibition, we examined structural changes in the level of pigment-protein complexes in cucumber leaves in comparison with pea leaves. The complexes were separated on a native green gel and an increase in the intensity of a band was observed only in light-chilled cucumber leaves. The 77 K fluorescence emission spectrum of this green band indicated that the band was mainly composed of PSI with light-harvesting complex I. Each lane was cut from the green gel and separated on a fully denaturing SDS-PAGE in the second dimension. The new green gel band observed after light-chilling in cucumber leaves lacked 19, 18, and 16.5 kDa polypeptides. These results suggest that light-chilling facilitates the release of three peripheral polypeptides as an early event of chilling stress in vivo, which results in the inactivation of PSI in intact cucumber leaves.
Oh
Min-Hyuk
MH
Department of Molecular Biology, Pusan National University, Busan 609-735, Korea.
Safarova
Rana B
RB
Eu
Young-Jae
YJ
Zulfugarov
Ismayil S
IS
Kim
Jin-Hong
JH
Hwang
Hong Jin
HJ
Lee
Chin Bum
CB
Lee
Choon-Hwan
CH