Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in Chlamydomonas reinhardtii by sensing CO2 availability.
Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a set of genes for a carbon-concentrating mechanism (CCM) to acclimate to CO2-limiting conditions. This acclimation is modulated by some mechanisms in the cell to sense CO2 availability. Previously, a high-CO2-requiring mutant C16 defective in an induction of the CCM was isolated from C. reinhardtii by gene tagging. By using this pleiotropic mutant, we isolated a nuclear regulatory gene, Ccm1, encoding a 699-aa hydrophilic protein with a putative zinc-finger motif in its N-terminal region and a Gln repeat characteristic of transcriptional activators. Introduction of Ccm1 into this mutant restored an active carbon transport through the CCM, development of a pyrenoid structure in the chloroplast, and induction of a set of CCM-related genes. That a 5,128-base Ccm1 transcript and also the translation product of 76 kDa were detected in both high- and low-CO2 conditions suggests that CCM1 might be modified posttranslationally. These data indicate that Ccm1 is essential to control the induction of CCM by sensing CO2 availability in Chlamydomonas cells. In addition, complementation assay and identification of the mutation site of another pleiotropic mutant, cia5, revealed that His-54 within the putative zinc-finger motif of the CCM1 is crucial to its regulatory function.
Fukuzawa
H
H
Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan. fukuzawa@lif.kyoto-u.ac.jp
Miura
K
K
Ishizaki
K
K
Kucho
K I
KI
Saito
T
T
Kohinata
T
T
Ohyama
K
K
D048868:Adaptor Proteins, Signal Transducing; D020418:Algal Proteins; D000595:Amino Acid Sequence; D000818:Animals; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology; D016825:Chlamydomonas reinhardtii / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics; D010940:Plant Proteins; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors; D014170:Transformation, Genetic; D016335:Zinc Fingers
D048868:Adaptor Proteins, Signal Transducing; D020418:Algal Proteins; C425932:Cia5 protein, Chlamydomonas reinhardtii; D009687:Nuclear Proteins; D010940:Plant Proteins; D011506:Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; C425934:ccm1 protein, Chlamydomonas reinhardtii; D002245:Carbon Dioxide; D002244:Carbon