Arabidopsis CHLI2 Can Substitute for CHLI1

Huang, Yi-Shiuan; Li, Hsou‐min

doi:10.1104/pp.109.135368

Cited by 85 publications

(101 citation statements)

References 27 publications

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“…In this study, the homozygous ell mutant possessed barely detectable chlorophyll and the heterozygote chlorophyll content was about half (48 %) of that in the wild type (Fig. 1b), consistent with other ell homologous mutations in Arabidopsis, barley, and maize (Huang and Li 2009;Hansson et al 1999;Sawers et al 2006). These results suggest that Mg-chelatase also plays a vital role in controlling the rate of chlorophyll biosynthesis.…”

Section: Discussionsupporting

confidence: 90%

A Point Mutation of Magnesium Chelatase OsCHLI Gene Dampens the Interaction Between CHLI and CHLD Subunits in Rice

et al. 2015

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Proper chloroplast development and chlorophyll biosynthesis are essential for the photoautotrophic plants. The insertion of magnesium (Mg 2+ ) into protoporphyrin IX (Proto), catalyzed by magnesium chelatase (Mgchelatase), is the first committed step of chlorophyll biosynthesis. In dicot plants, a proposed model revealed that Mg-chelatase I subunit (CHLI) and Mg-chelatase D subunit (CHLD) can interact directly; however, their relation remains elusive in rice, a monocot model plant. In this study, we characterized a chlorophyll-deficiency mutant, etiolated leaf and lethal (ell), which displayed a yellow leaf in young seedlings and became lethal after three-leaf stage. Chlorophyll content in homozygous ell mutant was approximately 1 % of that in the wild type. Besides, chloroplast development in the mutant was entirely arrested and no thylakoid structure was observed. By map-based cloning, the ell locus was delimited to a 3.9-Mb interval in chromosome 3. A single-base mutation (G529C) inOsCHLI was identified, leading to an amino acid substitution (G177R) in a highly conserved region. Compared with the wild type, more Proto but less magnesium protoporphyrin IX (Mg-Proto) was measured in the ell mutant. Using protoplast transfection and callus transformation, we found that exogenous OsCHLI could consistently recover the lesion of chloroplast in the ell mutant. By subcellar localization analysis, OsCHLI was detected in the chloroplast. Despite the secondary structure of OsCHLI that was predicted to be altered in the mutant, the point mutation did not affect subcellular localization. Real-time PCR demonstrated that the ell mutation induced significantly transcriptional downregulation of the photosynthesis-associated nuclear and plastid genes. Additionally, yeast-two-hybrid experiments indicated that the single amino acid substitution blocked the intrinsic interaction between OsCHLI and OsCHLD. Moreover, OsCHLI showed physical interactions with some thioredoxins (TRXs), suggesting a similar regulatory mechanism of Mg-chelatase activity in both monocot and dicot plants. Keywords Rice . Map-based cloning . Mg-chelatase . OsCHLI subunit . OsCHLD subunit . Thioredoxin Abbreviations Proto Protoporphyrin IX Mg-chelatase Magnesium chelatase ell Etiolated leaf and lethal Mg-Proto Magnesium protoporphyrin IX TRX Thioredoxin EMS Ethyl methyl sulfonate CHLH Mg-chelatase H subunit Electronic supplementary material The online version of this article (

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Section: Discussionsupporting

confidence: 90%

A Point Mutation of Magnesium Chelatase OsCHLI Gene Dampens the Interaction Between CHLI and CHLD Subunits in Rice

et al. 2015

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“…The residues at C-terminal region, A1253, R1269, and R1290, appear to be important for plastid signaling though they have less contribution to Mg-chelatase activity. Because the domains containing these residues (domain I & the end of V to VI) locate outer region of the CHLH protein, the mutation in these residues may interfere with the interaction of other components such as CHLI, CHLD, and GUN4 that are involved in plastid signaling (Strand et al, 2003; Huang and Li, 2009; Adhikari et al, 2011). …”

Section: Discussionmentioning

confidence: 99%

CHLH/GUN5 Function in Tetrapyrrole Metabolism Is Correlated with Plastid Signaling but not ABA Responses in Guard Cells

2016

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Expression of Photosynthesis-Associated Nuclear Genes (PhANGs) is controlled by environmental stimuli and plastid-derived signals (“plastid signals”) transmitting the developmental and functional status of plastids to the nucleus. Arabidopsis genomes uncoupled (gun) mutants exhibit defects in plastid signaling, leading to ectopic expression of PhANGs in the absence of chloroplast development. GUN5 encodes the plastid-localized Mg-chelatase enzyme subunit (CHLH), and recent studies suggest that CHLH is a multifunctional protein involved in tetrapyrrole biosynthesis, plastid signaling and ABA responses in guard cells. To understand the basis of CHLH multifunctionality, we investigated 15 gun5 missense mutant alleles and transgenic lines expressing a series of truncated CHLH proteins in a severe gun5 allele (cch) background (tCHLHs, 10 different versions). Here, we show that Mg-chelatase function and plastid signaling are generally correlated; in contrast, based on the analysis of the gun5 missense mutant alleles, ABA-regulated stomatal control is distinct from these two other functions. We found that none of the tCHLHs could restore plastid-signaling or Mg-chelatase functions. Additionally, we found that both the C-terminal half and N-terminal half of CHLH function in ABA-induced stomatal movement.

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“…The Arabidopsis Mg-chelatase I subunit single mutant (cs or ch42) did not show a gun phenotype, even though they have less potential for MgProto IX production than the H subunit mutant gun5 (Mochizuki et al, 2001). Only the chli1/chli2 double mutant showed a gun phenotype upon NF treatment (Huang and Li, 2009). In our previous study, a POR-less barley mutant accumulated two times the amount of Mg-Proto IX than the wild-type, but its Lhcb mRNA level was the same as the wild-type (Liu et al, 2008).…”

Section: Introductionmentioning

confidence: 96%

Transient accumulation of Mg-protoporphyrin IX regulates expression of PhANGs – New evidence for the signaling role of tetrapyrroles in mature Arabidopsis plants

Zhang

Yuan

Hong

et al. 2011

Journal of Plant Physiology

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Arabidopsis CHLI2 Can Substitute for CHLI1

Cited by 85 publications

References 27 publications

A Point Mutation of Magnesium Chelatase OsCHLI Gene Dampens the Interaction Between CHLI and CHLD Subunits in Rice

A Point Mutation of Magnesium Chelatase OsCHLI Gene Dampens the Interaction Between CHLI and CHLD Subunits in Rice

CHLH/GUN5 Function in Tetrapyrrole Metabolism Is Correlated with Plastid Signaling but not ABA Responses in Guard Cells

Transient accumulation of Mg-protoporphyrin IX regulates expression of PhANGs – New evidence for the signaling role of tetrapyrroles in mature Arabidopsis plants

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