Chlorophyll-deficient mutants of Chlamydomonas reinhardtii that accumulate magnesium protoporphyrin IX

Linda Meinecke, Ali Alawady, Michael Schroda, Robert Willows, Marilyn C. Kobayashi, Krishna K. Niyogi, Bernhard Grimm, Christoph F. Beck

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Two Chlamydomonas reinhardtii mutants defective in CHLM encoding Mg-protoporphyrin IX methyltransferase (MgPMT) were identified. The mutants, one with a missense mutation (chlM-1) and a second mutant with a splicing defect (chlM-2), do not accumulate chlorophyll, are yellow in the dark and dim light, and their growth is inhibited at higher light intensities. They accumulate Mg-protoporphyrin IX (MgProto), the substrate of MgPMT and this may be the cause for their light sensitivity. In the dark, both mutants showed a drastic reduction in the amounts of core proteins of photosystems I and II and lightharvesting chlorophyll a/b-binding proteins. However, LHC mRNAs accumulated above wild-type levels. The accumulation of the transcripts of the LHC and other genes that were expressed at higher levels in the mutants during dark incubation was attenuated in the initial phase of light exposure. No regulatory effects of the constitutively 7- to 18-fold increased MgProto levels on gene expression were detected, supporting previous results in which MgProto and heme in Chlamydomonas were assigned roles as second messengers only in the transient activation of genes by light.

Original languageEnglish
Pages (from-to)643-658
Number of pages16
JournalPlant Molecular Biology
Volume72
Issue number6
DOIs
Publication statusPublished - 2010

Keywords

  • Chlamydomonas
  • Mg protoporphyrin IX methyltransferase mutants
  • MgProtoporphyrin IX accumulation
  • gene expression
  • signaling

Fingerprint Dive into the research topics of 'Chlorophyll-deficient mutants of Chlamydomonas reinhardtii that accumulate magnesium protoporphyrin IX'. Together they form a unique fingerprint.

Cite this