Control by phytochrome of the appearance of ribulose-1,5-bisphosphate carboxylase and the mRNA for its small subunit

1993

Planta

Self Cite

Homologous cDNA clones of the nuclear-codes 23- and 33-kDa polypeptides of the oxygen-evolving system, as well as the Rieske iron/sulfur protein, were expressed in antisense or sense orientation under the control of the 35S RNA cauliflower mosaic virus promoter in transgenic tobacco (Nicotiana tabacum, L.) in order to modulate stationary concentrations of transcripts for studying relationships between transcript and protein levels. In all instances, in individuals that contained as little as 10% or less of the transcripts of untransformed plants, the corresponding protein levels were not notably altered. This indicated that the mRNA levels for components under study are not rate-limiting for protein accumulation and that severely reduced amounts of these transcripts still allow normal plant development. Overexpression of the 23-kDa polypeptide by the corresponding cDNA integrated in sense orientation resulted in both higher mRNA and protein levels without detectable enhancement of oxygen evolution. At least some of the excess protein was found in the soluble fraction and not associated with the photosystem-II reaction center. An attempt has been made to reconcile the varied responses obtained using these approaches with different expression patterns.

Section: Introductionmentioning

confidence: 98%

Antisense RNA for components associated with the oxygen-evolving complex and the Rieske iron/sulfur protein of the tobacco thylakoid membrane suppresses accumulation of mRNA, but not of protein

Palomares

Herrmann

1993

Planta

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“…The photocontrolled appearance and accumulation of nuclear-encoded polypeptides seem to be regulated both transcriptionally and post-transcriptionally (Tobin and Silverthorne, 1985 ;Gilmartin et al, 1990;Thompson and White, 1991 ;Herrmann et al, 1991Herrmann et al, , 1992. The changes in transcription rates as well as in steady-state mRNA levels of both plastid and nuclear genes are frequently not matched by comparable changes of the corresponding polypeptides (Schmidt and Mishkind, 1983;Herrmann et al, 1985, 1991: Oelmuller et al, 1986aSchuster et al, 1988;Flieger et al, 1993;Bolle et al, 1993). For example, transcripts from all nuclear genes studied accumulate with comparable kinetics when spinach seedlings are transferred from darkness to light, while the corresponding proteins display pronounced differences: some of them, for instance, the ATP synthase subunits y and 6, the Rieske Fe/S protein of the cytochrome complex, the peripheral polypeptides plastocyanin, ferredoxin-NADP'-oxidoreductase, and the extrinsic polypeptides of the oxygen-evolving system are synthesized effectively from minute RNA amounts in the dark and accumulate only moderately during greening.…”

mentioning

confidence: 99%

Post‐transcriptional and post‐translational regulatory steps are crucial in controlling the appearance and stability of thylakoid polypeptides during the transition of etiolated tobacco seedlings to white light

Palomares

Herrmann

European Journal of Biochemistry

1993

We have investigated the expression of nuclear-encoded chloroplast proteins that are not associated with chlorophyll (the lumenal 33-kDa and 23-kDa polypeptides of the oxygen-evolving system of photosystem 11, plastocyanin and the Rieske Fe/S protein) by comparing mRNA-accumulation rates with those of the corresponding proteins during illumination of etiolated tobacco seedlings. Using subcellular fractionation, pulsekhase, Northern and Western techniques, we found that the biogenesis and stability of these proteins are regulated both translationally, as well as post-translationally, including the efficiency of mRNA uptake into polysomes, processes that operate between translation and assembly or monitor the status (soluble and membrane-attached) of a terminally processed polypeptide. Polypeptide synthesis is generally not limited by mRNA amounts. For instance, steady-state transcript levels may increase 10-fold during illumination, while those associated with polycomes increase only 2-3-fold without measurable influence on the rate of protein synthesis. The 23-kDa and Rieske polypeptides are predominantely membrane associated, but plastocyanin and the 33-kDa polypeptide are distributed among both soluble and membrane-associated protein fractions. Plastocyanin appears to be comparably stable in both forms. However, for the 33-kDa polypcptide, only the membrane-attached form is stable (> 8 h) and only this pool increases upon illumination. Its soluble form is rapidly degraded with a half-life of approximately 1 h under the chosen conditions. Our findings probably reflect part of a more general regulatory principle operating in the differentiation and maintenance of subcellular structure.Thylakoid membranes of higher plants consist of approximately 70 polypcptide species, the majority of which are assembled in five major multisubunit complexes, the photosystems I and 11, the cytochrome complex, the ATP synthase and the NAD(P)H dehydrogenase. Most of the genes that code for these polypeptides have been isolated during the past decadc (summarized in Hallick, 1989, andHemnann et al., 1991); approximately half of them originate in plastids, the remaining in the nucleus. The dual genetic origin and a vast difference of 2-3 orders of magnitude in genc-copy number between nucleus and plastids implies that the synthcsis and assembly of thylakoid polypeptides must be highly coordinated in time and space, with regard to stoichiometry, and in response to external stimuli.Light plays a crucial role among the various factors that influence the biosynthesis of the photosynthetic membranc and appears to operate at various levels. The light-dependent synthesis of polypeptides made in plastids is generally controlled post-transcriptionally (Herrmann et al

“…In mustard seedlings 15 min of photodamage to the plastids already prevents further accumulation of the nuclear-and plastidencoded RuBPCase in subsequent non-photooxidative far-red light, while 1 h' of photodamage is required to obtain the same effect for the plastidic enzyme glyceraldehyde-3-phosphate dehydrogenase, which is only nuclear-encoded (Oelmuller et al, 1986b). The decrease in the amount of plastidic components during photodamage is primarily due to a direct damage of already formed proteins rather than to the normal turnover in the absence of de novo synthesis: the level of the relatively stable RuBPCase in mustard (Schuster et al, 1988a) decreases rapidly during photodamage as long as Chl is available for the perception of the 'destructive' light, while the enzyme level remains stable as soon as all Chl is photooxidized (Oelmiiller et a / . , 1986b.…”

mentioning

confidence: 99%

Photooxidative Destruction of Chloroplasts and Its Effect on Nuclear Gene Expression and Extraplastidic Enzyme Levels *

Photochem & Photobiology

1989

202

139

Abstract-The cooperation between the nuclear and plastidic genome has been investigated extensively and it is generally accepted that plastidic development is controlled by the genetic information encoded in the nucleus (Ellis, 1981). It was discovered only recently that plastids are also involved in controlling extraplastidic events. If carotenoid-free plastids are destroyed by photooxidation. expression of plastidic proteins which are encoded in the nucleus is reduced or prevented. Thus is has been postulated that a signal which derives from the plastids controls the expression of these genes in the nucleus. Moreover. extraplastidic enzymes with functions related to intact plastids (such as nitrate reductase and peroxisomal enzymes) are also affected by this treatment, while (ph0to)morphogenesis and extraplastidic compounds not directly related to plastidic functions seem to be unaffected. Since the damage is restricted exclusively to the plastids and even the outer envelope membrane appears to be unimpaired, photooxidative destruction of carotenoid-free plastids is often used as a tool to investigate nuclear plastid interaction. This review briefly describes the events occurring during photodamage, analyzes the consequences for extraplastidic events, and discusses the implication of a plastidic signal(s) in controlling the expression of nuclear genes which code for plastidic proteins.