Heat-Shock or Red Light-Pulse Induced Circadian Rhythm in the Capacity for Chlorophyll Synthesis in Etiolated Bean or Pea Leaves

Argyroudi‐Akoyunoglou, J. H.; Anastassiou, Rania; Bei‐Paraskevopoulou, Thalia

doi:10.1007/978-94-009-0383-8_73

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…Even though this protease acts on the same substrate protein as that in the present study on degradation of excess functionally assembled LHCII, it appears not to have the same general properties since the Chtamydomonus enzyme could not be inactivated by protease inhibitors and was not dependent on ATP (Hoober and Hughes, 1992). In addition, LHCII degradation has been shown to be activated by the detergent Triton X-100 in pea thylakoids (Argyroudi-Akoyunoglou et al, 1992). It remains to be established whether or not the presently identified proteolytic activity is connected to the clp-proteases, which are of the serine type and dependent on ATP (Goldberg, 1992).…”

Section: Discussionmentioning

confidence: 51%

Regulatory Proteolysis of the Major Light‐Harvesting Chlorophyll a/b Protein of Photosystem II by a Light‐Induced Membrane‐Associated Enzymic System

Lindahl

Yang

Andersson

1995

European Journal of Biochemistry

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An endogenous proteolytic activity associated with spinach chloroplast thylakoid membranes has been identified. This enzymic activity is involved in the degradation of the major light-harvesting chlorophyll alb protein of photosystem I1 (LHCII) in response to exposure of leaves to increased irradiance. This proteolysis of LHCII requires an induction period and can only be detected 48-72 hours after transfer of the plants from low-intensity to high-intensity light. Once initiated by high-intensity light, the degradation of LHCII can readily occur in complete darkness. The proteolysis can, after induction in vivo, be experimentally followed in vitro, both in isolated intact chloroplasts and thylakoid membranes. The proteolytic process is strictly dependent on ATP and the protease involved is of the serine or cysteine type. The activity can be released from isolated thylakoid membranes by washing with high concentrations of NaCl and reconstituted by readdition of the desalted wash supernatant. It is concluded that the protease is extrinsically bound to the outer surface of the stroma-exposed regions of the stacked thylakoid membrane. The mechanism for the induction of the proteolytic process as well as its relation to previously described thylakoid proteases will be discussed.

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Section: Discussionmentioning

confidence: 51%

Regulatory Proteolysis of the Major Light‐Harvesting Chlorophyll a/b Protein of Photosystem II by a Light‐Induced Membrane‐Associated Enzymic System

Lindahl

Yang

Andersson

1995

European Journal of Biochemistry

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“…V/a such cation concentration changes, Pfr may similarly affect the oscillations in the degrading activity of thylakoids obtained from etiolated leaves following a Red light pulse. Phytochrome is believed to synchronize the biological clock in etiolated bean leaves, and to affect circadian oscillations in LHC II mRNA, capacity for Chl synthesis and stabilization of the LHC II protein in total leaf extracts (Tavladoraki et al 1989;Argyroudi-Akoyunoglou et al 1991;BeiParaskevopoulou and Argyroudi-Akoyunoglou 1991;Bei-Paraskevopoulou et al 1995). How this synchronization occurs is unknown.…”

Section: Discussionmentioning

confidence: 99%

“…(Vierstra 1993;Schmidt and Mishkind 1983;Robinson and Ellis 1984;Liu and Jagendorf 1984;Merchant and Bogorad 1986;Reisman and Ohad 1986;Kirwin et al 1987;Inagaki et al 1989;Salter et al 1992). Lately, proteolytic activity has been also detected in thylakoids towards the mature LHC II in Chlamydomonas, barley and bean (Honda et al 1991;Hoober and Hughes 1992;Argyroudi-Akoyunoglou et al 1992). …”

Section: Introductionmentioning

confidence: 99%

Thylakoid-bound proteolytic activity against LHC II apoprotein in bean

Anastassiou

Argyroudi‐Akoyunoglou

1995

Photosynth Res

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Triton X-100 solubilized thylakoids, isolated from Phaseolus vulgaris chloroplasts, degrade endogenous or exogenously added LHC II. The degradation, as monitored by immunodetection of the remaining LHC II after incubation at 37°C, is activated by Mg(++) and inhibited by pCMB, EDTA, PMSF and benzamidine; the activity under high light conditions parallels chlorophyll photooxidation. The thylakoid-bound proteolytic activity is under phytochrome control. Etiolated plants pretreated by a white light pulse, and kept in the dark thereafter, show enhanced proteolytic activity, which follows rhythmical oscillations. On the other hand, chloramphenicol pretreatment of etiolated plants, prior to their transfer to continuous light, reduces the proteolytic activity against LHC II. The results suggest that the degradation involves a serine type protease, which depends on SH group(s), coded by the plastid genome; the protease action on LHC II is regulated by Mg(++), phytochrome, the biological clock and chlorophyll accumulation in the thylakoid. The stroma lamellar fraction, separated from French press disrupted chloroplasts, exhibits higher activity towards exogenous LHC II than the grana fraction. The stroma of intact chloroplasts exhibits also high proteolytic activity, which is drastically reduced when the lysis medium is supplemented with cations. This suggests that the protease is bound mainly on stroma lamellae and peripheral granal membranes, its association to the membranes being possibly under cation control.

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