<i>genome uncoupled1</i> Mutants Are Hypersensitive to Norflurazon and Lincomycin

Zhao, Xiaobo; Huang, Jianyan; Chory, Joanne

doi:10.1104/pp.18.00772

Cited by 31 publications

(23 citation statements)

References 20 publications

(3 reference statements)

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“…Because most of the proteins found in green plastids are encoded in the nucleus (Timmis et al , 2004; Ferro et al , 2010; Terashima et al , 2011), the plastid communicates with the nucleus to adequately respond to external cues (Chan et al , 2016). The molecular biological chassis underpinning plastid retrograde signaling has been the subject of much recent debate and conceptual reordering (Page et al , 2017; Song et al , 2018; Wu et al , 2018; Zhao et al , 2018; Kacprzak et al , 2019; Shimizu et al , 2019). These discussions nevertheless revolve around a (relatively) robust core set of proteins including those that are tetrapyrrole biosynthesis‐associated (Chan et al , 2016; Hernández‐Verdeja and Strand, 2018).…”

Section: Introductionmentioning

confidence: 99%

Heat stress response in the closest algal relatives of land plants reveals conserved stress signaling circuits

Vries

Curtis

et al. 2020

The Plant Journal

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SUMMARY All land plants (embryophytes) share a common ancestor that likely evolved from a filamentous freshwater alga. Elucidating the transition from algae to embryophytes – and the eventual conquering of Earth’s surface – is one of the most fundamental questions in plant evolutionary biology. Here, we investigated one of the organismal properties that might have enabled this transition: resistance to drastic temperature shifts. We explored the effect of heat stress in Mougeotia and Spirogyra, two representatives of Zygnematophyceae – the closest known algal sister lineage to land plants. Heat stress induced pronounced phenotypic alterations in their plastids, and high‐performance liquid chromatography‐tandem mass spectroscopy‐based profiling of 565 transitions for the analysis of main central metabolites revealed significant shifts in 43 compounds. We also analyzed the global differential gene expression responses triggered by heat, generating 92.8 Gbp of sequence data and assembling a combined set of 8905 well‐expressed genes. Each organism had its own distinct gene expression profile; less than one‐half of their shared genes showed concordant gene expression trends. We nevertheless detected common signature responses to heat such as elevated transcript levels for molecular chaperones, thylakoid components, and – corroborating our metabolomic data – amino acid metabolism. We also uncovered the heat‐stress responsiveness of genes for phosphorelay‐based signal transduction that links environmental cues, calcium signatures and plastid biology. Our data allow us to infer the molecular heat stress response that the earliest land plants might have used when facing the rapidly shifting temperature conditions of the terrestrial habitat.

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Section: Introductionmentioning

confidence: 99%

Heat stress response in the closest algal relatives of land plants reveals conserved stress signaling circuits

Vries

Curtis

et al. 2020

The Plant Journal

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“…The GUN genes appear to promote chloroplast function (1,2). Consistent with this observation, all of the gun mutants that were isolated from gun mutant screens are more sensitive to the inhibitors that are typically used to block chloroplast biogenesis in these types of experiments (e.g., norflurazon and lincomycin) than wild type (5)(6)(7). Norflurazon blocks chloroplast biogenesis by inhibiting the biosynthesis of carotenoids, which are essential photosynthetic pigments.…”

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confidence: 61%

RNA editing implicated in chloroplast-to-nucleus communication

Larkin

2019

Proc. Natl. Acad. Sci. U.S.A.

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“…A major difficulty in the elucidation of the molecular mechanism and the precise role of GUN1 in retrograde signaling arises from the fact that gun1 mutants are virtually indistinguishable from wild type, with only a small percentage of gun1 mutants developing chlorophyll-deficient cotyledons under optimal growth conditions (Ruckle et al, 2007). However, seedlings lacking GUN1 are hypersensitive to low concentrations of both norflurazon (20 nM) and lincomycin (22 µM), as revealed by a small pale yellow or white cotyledon phenotype, while wild-type seedlings form fully developed green cotyledons under the same growth conditions (Song et al, 2018; Zhao et al, 2018; see also Figure S2a). Accordingly, when the gun1-102 mutant was combined with mutations that impair plastid protein synthesis, such as prps17-1 , prpl11-1 and prpl24-1 , the corresponding double mutants were seedling lethal (Tadini et al, 2016; Paieri et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

GUN1 influences the accumulation of NEP-dependent transcripts and chloroplast protein import in Arabidopsis cotyledons upon perturbation of chloroplast protein homeostasis

Tadini

Peracchio

Trotta

et al. 2019

Preprint

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Correct chloroplast development and function require coordinated expression of chloroplast and nuclear genes. This is achieved through chloroplast signals that modulate nuclear gene expression in accordance with the chloroplast's needs. Genetic evidence indicates that GUN1, a chloroplast-localized pentatricopeptide-repeat (PPR) protein with a C-terminal Small MutS-Related (SMR) domain, is involved in integrating multiple developmental and stress-related signals in both young seedlings and adult leaves. Recently, GUN1 was found to interact physically with factors involved in chloroplast protein homeostasis, and with enzymes of tetrapyrrole biosynthesis in adult leaves that function in various retrograde signaling pathways. Here we show that, following perturbation of chloroplast protein homeostasis i) by growth in lincomycin-containing medium, or ii) in mutants defective in either the FtsH protease complex (ftsh), plastid ribosome activity (prps21-1 and prpl11-1) or plastid protein import and folding (cphsp70-1), GUN1 influences NEP-dependent transcript accumulation during cotyledon greening and also intervenes in chloroplast protein import. import Chloroplast biogenesis is achieved through a cascade of events that include cytosolic synthesis of chloroplasttargeted proteins, followed by their import, assembly and folding, while unfolded/misfolded proteins and damaged or malformed chloroplasts are degraded (Sakamoto et al., 2008; Jarvi and López-Jauez, 2013; Izumi and Nakamura, 2018; Otegui, 2018). Most chloroplast-targeted proteins enter the chloroplasts via the protein complexes TOC ('translocon at outer envelope of chloroplast') and TIC ('translocon at inner envelope of chloroplast'). On the cytosolic side, precursor proteins are directed to the Toc34 and Toc159 receptors through the interaction of their chloroplast-targeting peptides with the chaperone heat shock protein 90 (Hsp90) and the guidance complex formed by Hsp70 and a 14-3-3 protein. Active transport through the chloroplast envelope is then mediated by an ATP-dependent import motor, consisting of Hsp70, Hsp90 and the stromal Hsp93 (ClpC2) proteins (Kessler and Schnell, 2009; Sjuts et al., 2017).On the stromal side, transcription of the plastid-encoded genes in higher plants requires two different RNA polymerases: the nuclear-encoded RNA polymerase (NEP), also termed RpoTp (located specifically in the chloroplasts and encoded by the RPOT3 gene) or RpoTmp (located both in mitochondria and plastids and encoded by the RPOT2 gene) and the plastid-encoded RNA polymerase (PEP) (Yu et al., 2014; Börner et al., 2015). NEP is a monomeric T3-T7 bacteriophage-type RNA polymerase that is mainly responsible for transcribing housekeeping genes, whereas PEP is a bacterial-type multisubunit enzyme largely tasked with transcribing photosynthesis-related genes. Chloroplast development is associated with a shift in the primary RNA polymerase from NEP to PEP. Furthermore, compensatory responses can be observed between the two RNA polymerases, as depletion of PEP activ...

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genome uncoupled1 Mutants Are Hypersensitive to Norflurazon and Lincomycin

Cited by 31 publications

References 20 publications

Heat stress response in the closest algal relatives of land plants reveals conserved stress signaling circuits

Heat stress response in the closest algal relatives of land plants reveals conserved stress signaling circuits

RNA editing implicated in chloroplast-to-nucleus communication

GUN1 influences the accumulation of NEP-dependent transcripts and chloroplast protein import in Arabidopsis cotyledons upon perturbation of chloroplast protein homeostasis

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