Co

(prokaryotic?/prokaryotic) ■ pnmary endosymbiosis - (eukaryotic/proltaryoöc) heterotrophic autotrophic

{animals, fungi) (plants)

(prokaryotic?/prokaryotic) ■ pnmary endosymbiosis - (eukaryotic/proltaryoöc) heterotrophic autotrophic

{animals, fungi) (plants)

secondly eryJosymbtosis (euitaryobcfeukaryotic)

secondly eryJosymbtosis (euitaryobcfeukaryotic)

endosymbcsH ieufcanrcli&'Mcondary eu*aryotic]
i V.-

Color Plate 2. Simplified scheme illustrating the principal steps in the origin and evolution of photosynthetic (and respiratory) organelles and of plant cells. Primary mitochondria and plastids resulting from phagocytosis of (a) a heterotrophic prokaryote (a-proteobacterium) into a prokaryotic or protoeukaryotic (see text) host cell, or (b) of a photoautotrophic prokaryote (cyanobacterium) into a eukaryotic cell, (c-f) Complex plastids generated by secondary endosymbiosis, i.e. by engulfment of photoautotrophic microbes (microalgae) into heterotrophic (or autotrophic) cells. Stage (d) is hypothetical, (g-h) Plastids generated by tertiary endosymbiosis. Modified from Herrmann (1997). (See Chapter 1, p. 6.)

Color Plate 3. Localization of enzymes of the central carbohydrate metabolism in spinach. Suggested evolutionary origins for the nuclear genes are color coded. Enzymes regulated through the thioredoxin system (Fig. 1) are indicated. Enzyme abbreviations are: FBA, fructose-1,6-biophosphate aldolase; FBP, fructose-1,6-bisphosphatase; GAPDH, glyceraldehyde-3-P dehydrogenase; PGK, 3-phosphoglycerate kinase; PRI, ribulose-5-P isomerase; PRK, phosphoribulokinase; RPE, ribulose-5-P 3-epimerase; SBP, sedoheptulose-1,7-bisphosphatase; TLK, transketolase; TPI, triosephosphate isomerase; TAL, transaldolase; GPI, glucose-6-P isomerase; G6PDH, glucose-6-P dehydrogenase; 6GPDH, 6-phosphogluconate dehydrogenase; pGluM, phosphoglucomutase; PGM, phosphoglyceromutase; PFK, phosphofructokinase (pyrophosphate and ATP-dependent); ENO, enolase; PYK, pyruvate kinase; PDC, pyruvate dehydrogenase complex (El, E2, E3 components); and T, translocator. PDC is a multienzyme complex, but only one set of components is drawn here. Open arrowheads indicate transport rather than conversion. Solid arrowheads indicate physiologically irreversible reactions. For details, Martin and Herrmann (1998). (See Chapter 1, p. 9.)

Color Plate 4a. Phytochrome signaling pathways identified by microinjection approaches. PhyA pathways are indicated in red, PhyB in green. Reciprocal negative regulation (denoted -ve) between the cGMP- and calcium-dependent pathways is indicated by dashed lines. Redox signals (denoted e") arising from plastoquinone are proposed to regulate the relative activities of the two calcium-dependent pathways. For further details see Sections III and IV. Abbreviations: CHS, chalcone synthase; FNR, ferredoxin oxidoreductase; CAB, chlorophyll a,¿-binding proteins; AS1, asparagine synthetase. (See Chapter 3, p. 54.)

Color Plate 4b. A Simplified Model of Phytochrome Signal Transduction. Activated phytochrome (Pfr) is proposed to be phosphorylated and subsequently (a) to be translocated to the nucleus, (b) to activate calcium- and cGMP-dependent signaling pathways, or (c) to be sequestered away from the active pool by phytochrome kinase substrate 1 (PKS1), which in turn becomes phosphorylated by Pfr. Once inside the nucleus, Pfr can interact with PIF3 and cryptochomes (CRY) to control photoregulated gene expression. Additional nuclear factors such as HY5 and the COP/DET/FUS proteins may act as intermediates for photomorphogenesis either downstream of the cytoplasmic calcium and cGMP signals or downstream of the nuclear-localized phytochromes. The model is simplistic in that it does not account for differences between PhyA and PhyB signaling, e.g. the nuclear SP A1 and FAR1 proteins, that are specific for PhyA signaling (Hoecker et al., 1999; Hudson et al., 1999), are not shown. (See Chapter 3, p. 60.)

FBPase NADP-MDH

Color Plate 5. Structure of proteins constituting the ferredoxin/thioredoxin system and two target enzymes. The top of the figure shows the FTR (Synechocystis) from the side with the variable subunit in green and the catalytic subunit in red. The concave disk shape of the heterodimer allows simultaneous docking of a thioredoxin (on the left) and of a ferredoxin molecule (on the right). Two spinach chloroplast thioredoxins are given in surface view in the middle. The colors (as shown in the color-plate section of this book) represent the following residue type: green—Cys; red—charged (+ or -); blue—polar; yellow—polar; gray—backbone. The bottom structures represent spinach FBPase (only one subunit), with the regulatory loop carrying the Cys, extending out of the core structure, and oxidized sorghum NADP-MDH dimer with the disulfide bonds implicated in regulation. (See Chapter 20, p. 335.)

Phosphorylation Thylakoid Proteins

Color Plate 6. Phosphorylation of thylakoid proteins during various stages of Photosystem II photodamage-repair cycle in higher plants. Phosphorylation and migration of the photodamaged PS II from grana region of thylakoids to stroma-exposed membranes for repair are presented. LHCII phosphorylation occurs mainly at low light and is not shown in the figure. The various steps of the cycle, marked from 1 to 7, are described in the text. (See Chapter 23, p. 409.)

Color Plate 6. Phosphorylation of thylakoid proteins during various stages of Photosystem II photodamage-repair cycle in higher plants. Phosphorylation and migration of the photodamaged PS II from grana region of thylakoids to stroma-exposed membranes for repair are presented. LHCII phosphorylation occurs mainly at low light and is not shown in the figure. The various steps of the cycle, marked from 1 to 7, are described in the text. (See Chapter 23, p. 409.)

Color Plate 1. Systemic induction ofyiPJO-ii/Cexpression in transgenic Arabidopsis leaf tissue and the scheme illustrating the systemic acquired acclimation (SAA) mechanism. (A) Image of luciferase activity in relative light units (RLU). A part of the whole rosette (as shown) exposed to EL for 40 min, the arrow indicates the apical region of the rosette. A typical primary (1°) EL-exposed leaf and secondary (2°) LL-exposed leaf are shown (after Karpinski et al., 1999). (B) EL-induced permanent photodamage (PPD) and the SAA mechanism in plants. Induction of expression of the defense genes in the cell is controlled by plastoquinone dependent signaling (PQDS). SAA = systemic acquired acclimation at 200 ¿¿mol of photons m~2 s"1, EL = 2500 ¿¿mol of photons m~2 s~', LL = 200 ¿miol of photons m~2 s"1. (See Chapter 27, p. 481.)

This page intentionally left blank

Chapter 1

Was this article helpful?

0 0

Post a comment