Chlorophyll: a symptom and a regulator of plastid development

Authors

  • HOWARD THOMAS

    Corresponding author
    1. Cell Biology Department, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK
      E-mail: sid.thomas@bbsrc.ac.uk
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E-mail: sid.thomas@bbsrc.ac.uk

SUMMARY

The metabolism of chlorophylls and related tetrapyrroles directly influences, and is influenced by, the proteins and cell structures with which they are associated. During net accumulation, de-greening and at the steady state chlorophyll and its derivatives are important elements in the post-translational regulation of the expression of genes for chloroplast proteins. At the same time, they represent potential photodynamic hazards against which green cells need to have protective mechanisms. This review deals with genetic, chemical and environmental perturbations of chlorophyll biosynthesis that impact on protein stability, membrane organization and susceptibility to photodamage. NADPH-protochlorophyllide oxidoreductase is considered in detail as a pigment– protein regulating, and regulated by, chlorophyll metabolism. The question of the extent and significance of chlorophyll turnover at the steady state is addressed, with particular emphasis on the dynamics of the photosystem II reaction centre. The pathway of chlorophyll catabolism is described, along with its interrelationship with protein mobilization in chloroplast senescence. Finally, the structural basis of pigment-protein interaction and stability is examined, and the discussion ends by expressing some general thoughts about the control of protein lifetimes in the living cell.

Abbreviations
ALA

5-aminolaevulinate

LHCP

light-harvesting chlorophyll-binding protein

PLB

prolamellar body

POR

NADPH- protochlorophyllide oxidoreductase

Pr/Pfr

red/far-red absorbing forms of phytochrome

PS

Photosystem

Rubisco

ribulose-l,5- bisphosphate carboxylase/oxygenase

SSU

small subunit

WRL

weak red light

Ancillary

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