TY - JOUR
T1 - Chlorophyll-deficient mutants of Chlamydomonas reinhardtii that accumulate magnesium protoporphyrin IX
AU - Meinecke, Linda
AU - Alawady, Ali
AU - Schroda, Michael
AU - Willows, Robert
AU - Kobayashi, Marilyn C.
AU - Niyogi, Krishna K.
AU - Grimm, Bernhard
AU - Beck, Christoph F.
PY - 2010
Y1 - 2010
N2 - 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.
AB - 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.
KW - Chlamydomonas
KW - Mg protoporphyrin IX methyltransferase mutants
KW - MgProtoporphyrin IX accumulation
KW - gene expression
KW - signaling
UR - http://www.scopus.com/inward/record.url?scp=84856067322&partnerID=8YFLogxK
U2 - 10.1007/s11103-010-9604-9
DO - 10.1007/s11103-010-9604-9
M3 - Article
C2 - 20127142
AN - SCOPUS:84856067322
SN - 0167-4412
VL - 72
SP - 643
EP - 658
JO - Plant Molecular Biology
JF - Plant Molecular Biology
IS - 6
ER -