Recent advances in chlorophyll biosynthesis and breakdown in higher plants

Abstract

Chlorophyll (Chl) has unique and essential roles in photosynthetic light-harvesting and energy transduction, but its biosynthesis, accumulation and degradation is also associated with chloroplast development, photomorphogenesis and chloroplast-nuclear signaling. Biochemical analyses of the enzymatic steps paved the way to the identification of their encoding genes. Thus, important progress has been made in the recent elucidation of almost all genes involved in Chl biosynthesis and breakdown. In addition, analysis of mutants mainly in Arabidopsis , genetically engineered plants and the application of photo-reactive herbicides contributed to the genetic and regulatory characterization of the formation and breakdown of Chl. This review highlights recent progress in Chl metabolism indicating highly regulated pathways from the synthesis of precursors to Chl and its degradation to intermediates, which are not longer photochemically active.

An Intermediate Membrane Subfraction in Cyanobacteria Is Involved in an Assembly Network for Photosystem II Biogenesis

“…Possibly, the chlorophyllide a synthesized in TMs is converted faster into chlorophyll a. In chloroplasts, the respective enzyme, the chlorophyll synthase, has been localized exclusively in TMs, whereas activity measurements in Synechocystis revealed its presence in both TMs and perhaps the PDMs resembling thylakoid centers (19,25). As discussed previously (4), it also remains to be established whether the pool of chlorophyllide a in PDMs is synthesized by the light-dependent POR enzyme or the light-independent POR system in cyanobacteria (27).…”

“…This would not only ensure the availability of sufficient pigments to build up the photosynthetic apparatus but would also prevent the accumulation of free and potentially harmful chlorophyll and/or chlorophyll precursor molecules (16,17). Such coordination may be favored by co-localization of the machineries required for protein and pigment synthesis, as suggested by studies of the Pitt protein, which interacts with the light-dependent protochlorophyllide oxidoreductase (POR), an enzyme involved in the conversion of protochlorophyllide a into chlorophyllide a (4,11,18,19), a precursor of chlorophyll a. Intriguingly, both Pitt and POR are present in PDM fractions of wild-type cells, suggesting a role for PDMs not only in protein synthesis and assembly but also in pigment synthesis and insertion (4,18).…”

Functional Differentiation of Bundle Sheath and Mesophyll Maize Chloroplasts Determined by Comparative Proteomics

“…We quantified three enzymes in the tetrapyrrole synthesis pathway implicated in three steps of the chlorophyll/heme biosynthesis pathway: (1) formation of the precursor 5-aminolevulinic acid (ALA), (2) synthesis of protoporphyrin, and (3) incorporation of Mg 2þ into the porphyrin ring (for reviews, see Beale, 1999;Eckhardt et al, 2004). The formation of ALA is the limiting step for the rest of the pathway.…”

Rice Cytokinin GATA Transcription Factor1 Regulates Chloroplast Development and Plant Architecture

“…Since that time, there has been an intricate exchange of DNA between the chloroplast and plant nucleus, resulting in a highly complex system regulating chloroplast development and activity (Raven and Allen, 2003;Gould et al, 2008). The molecular aspects involved in chloroplast biogenesis (Kessler and Schnell, 2009;Okazaki et al, 2010;Pogson and Albrecht, 2011), chlorophyll biosynthesis (Eckhardt et al, 2004;Tanaka and Tanaka, 2007;Reinbothe et al, 2010), photosynthesis (Laisk et al, 2009), and carbon metabolism have been quite well documented in recent decades. However, plants rely on their immediate environment for the acquisition of resources (e.g.…”