Identifizierung und Analyse von Mutanten in der Chlorophyllbiosynthese der Grünalge Chlamydomonas reinhardtii

The green alga /Chlamydomonas/ can grow heterotrophically in the dark
using acetate. A collection of dark-grown brown, yellow and yellow-green
/Chlamydomonas/ mutants, which were derived from UV and insertional
mutagenesis, was selected by the inability or strong inhibition to grow
photoautotrophically under normal light condition. These mutant
phenotypes would likely be lethal in plants. The/ Chlamydomonas/ mutants
are likely candidates for defects in chlorophyll biosynthesis, because
their light sensitivity allows them to grow in darkness or in dim light
only and distinguish them from mutants impaired in photosynthesis. An
initial HPLC-based quantitative analysis of porphyrins and Mg porphyrins
(up to divinyl and monovinyl derivatives of chlorophyllide and
geranylgeranylated chlorophyll) will facilitate to trace back new
mutants of impaired chlorophyll biosynthesis due to accumulation of
specific pathway intermediates. The mutated genes will be identified by
complementation studies using BAC clones containing genes encoding
enzymes of the tetrapyrrole pathway. Then, studies of expression and
enzyme activities of the deficient metabolic steps and other enzymes in
the pathway will enable us to characterize effects of deregulated
tetrapyrrole biosynthesis and elucidate possible unique regulatory
mechanisms of /Chlamydomonas,/ which are different from vascular plants.