Genetic Analysis Reveals Domain Interactions of Arabidopsis Hsp100/ClpB and Cooperation with the Small Heat Shock Protein Chaperone System

Lee, Ung; Wie, Chris; Escobar, Mindy; Williams, Bruce; Hong, Suk‐Whan; Vierling, Elizabeth

doi:10.1105/tpc.104.027540

Cited by 100 publications

(119 citation statements)

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“…Because HSP expression is known to be an important component of acquired thermotolerance, we also assayed the accumulation of different HSPs by protein blot analysis in the hot5 mutants ( Figure 2A). All of the hot5 alleles showed wild-type levels of Hsp101, which is essential for heat tolerance (Hong and Vierling, 2000), as well as cytosolic small HSPs of the class I and II types (Lee et al, 2005). Therefore, we conclude that hot5 mutants are not compromised in signaling mechanisms that lead to the expression of HSPs and that the absence of HSPs is not the cause of the hot5 thermotolerance defect.…”

Section: Gsnor In Thermotolerance 789mentioning

confidence: 74%

Modulation of Nitrosative Stress byS-Nitrosoglutathione Reductase Is Critical for Thermotolerance and Plant Growth inArabidopsis

et al. 2008

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Nitric oxide (NO) is a key signaling molecule in plants. This analysis of Arabidopsis thaliana HOT5 (sensitive to hot temperatures), which is required for thermotolerance, uncovers a role of NO in thermotolerance and plant development. HOT5 encodes S-nitrosoglutathione reductase (GSNOR), which metabolizes the NO adduct S-nitrosoglutathione. Two hot5 missense alleles and two T-DNA insertion, protein null alleles were characterized. The missense alleles cannot acclimate to heat as darkgrown seedlings but grow normally and can heat-acclimate in the light. The null alleles cannot heat-acclimate as light-grown plants and have other phenotypes, including failure to grow on nutrient plates, increased reproductive shoots, and reduced fertility. The fertility defect of hot5 is due to both reduced stamen elongation and male and female fertilization defects. The hot5 null alleles show increased nitrate and nitroso species levels, and the heat sensitivity of both missense and null alleles is associated with increased NO species. Heat sensitivity is enhanced in wild-type and mutant plants by NO donors, and the heat sensitivity of hot5 mutants can be rescued by an NO scavenger. An NO-overproducing mutant is also defective in thermotolerance. Together, our results expand the importance of GSNOR-regulated NO homeostasis to abiotic stress and plant development. INTRODUCTIONNitric oxide (NO) is a short-lived, endogenously produced radical that acts as a signaling molecule in all higher organisms Wendehenne et al., 2004;Delledonne, 2005;Crawford, 2006;Besson-Bard et al., 2008). Despite its deceivingly simple structure, the rich chemistry of NO in biological systems gives rise to multiple secondary and tertiary reaction products, greatly complicating our mechanistic understanding of NO-related effects (Stamler and Hausladen, 1998;Mancardi et al., 2004;Ridnour et al., 2004). Directly and via its various chemical transformations, NO not only accomplishes signaling functions but also acts as a redox modulator with both antioxidant (by quenching other radical reactions) and pro-oxidant (through the production of reactive nitrogen species; RNS) properties. In addition to effects on redox status, the formation of RNS leads to nitrosation, nitrosylation, and nitration reactions with other molecules. Most of the regulatory effects of NO are thought to be mediated through posttranslational protein modifications, including heme nitrosylation, Tyr nitration, Cys nitrosation, and even glutathiolation (Lindermayr et al., 2005;Aracena-Parks et al., 2006;Wang et al., 2006b;West et al., 2006;Zaninotto et al., 2006).In plants, NO is believed to be produced via two different enzymatic pathways (Guo et al., 2003;Crawford, 2006). In one pathway, it is generated by nitrate reductase through the successive reduction of nitrate to nitrite and further to NO. In the other pathway, L-Arg, plus oxygen and NADPH, is converted to NO and citrulline by the action of a NO synthase, although the actual existence and identity of plant NO synthase is currently unres...

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Section: Gsnor In Thermotolerance 789mentioning

confidence: 74%

Modulation of Nitrosative Stress byS-Nitrosoglutathione Reductase Is Critical for Thermotolerance and Plant Growth inArabidopsis

et al. 2008

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“…The Arabidopsis (Arabidopsis thaliana) T-DNA KO mutants hsp101, hot1-3, and hsa32-1 were as described previously (Lee et al, 2005;Charng et al, 2006). The double KO mutant hsp101 hsa32-1 was generated by crossing the single mutant lines and isolated from the offspring in the F2 generation.…”

Section: Plants Materials and Mutant Screenmentioning

confidence: 99%

Interplay between Heat Shock Proteins HSP101 and HSA32 Prolongs Heat Acclimation Memory Posttranscriptionally in Arabidopsis

Juan

Hsu

et al. 2013

Plant Physiology

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Heat acclimation improves the tolerance of organisms to severe heat stress. Our previous work showed that in Arabidopsis (Arabidopsis thaliana), the "memory" of heat acclimation treatment decayed faster in the absence of the heat-stress-associated 32-kD protein HSA32, a heat-induced protein predominantly found in plants. The HSA32 null mutant attains normal short-term acquired thermotolerance but is defective in long-term acquired thermotolerance. To further explore this phenomenon, we isolated Arabidopsis defective in long-term acquired thermotolerance (dlt) mutants using a forward genetic screen. Two recessive missense alleles, dlt1-1 and dlt1-2, encode the molecular chaperone heat shock protein101 (HSP101). Results of immunoblot analyses suggest that HSP101 enhances the translation of HSA32 during recovery after heat treatment, and in turn, HSA32 retards the decay of HSP101. The dlt1-1 mutation has little effect on HSP101 chaperone activity and thermotolerance function but compromises the regulation of HSA32. In contrast, dlt1-2 impairs the chaperone activity and thermotolerance function of HSP101 but not the regulation of HSA32. These results suggest that HSP101 has a dual function, which could be decoupled by the mutations. Pulse-chase analysis showed that HSP101 degraded faster in the absence of HSA32. The autophagic proteolysis inhibitor E-64d, but not the proteasome inhibitor MG132, inhibited the degradation of HSP101. Ectopic expression of HSA32 confirmed its effect on the decay of HSP101 at the posttranscriptional level and showed that HSA32 was not sufficient to confer long-term acquired thermotolerance when the HSP101 level was low. Taken together, we propose that a positive feedback loop between HSP101 and HSA32 at the protein level is a novel mechanism for prolonging the memory of heat acclimation.

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“…Besides the two nucleotide binding domains (NBDs), the N-terminal domain is assumed to play a role in substrate recognition, but appears to be dispensable for disaggregating small aggregates in vitro [9,10] and the C-terminal domain is involved in subunit oligomerization [11]. The M domain, which is specific for ClpB and its homolog Hsp104 and strictly required for protein disaggregation [12][13][14][15], is inserted into NBD1 and forms a large coiled-coil structure built by four helices.…”

Section: Introductionmentioning

confidence: 99%

Nucleotide utilization requirements that render ClpB active as a chaperone

Castillo¹,

Fernández-Higuero²,

Pérez-Acebrón³

et al. 2010

FEBS Letters

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a b s t r a c tClpB is a member of the AAA+ superfamily that forms a ring-shaped homohexamer. Each protomer contains two nucleotide binding domains arranged in two rings that hydrolyze ATP. We extend here previous studies on ClpB nucleotide utilization requirements by using an experimental approach that maximizes random incorporation of different subunits into the protein hexamer. Incorporation of one subunit unable to bind or hydrolyze ATP knocks down the chaperone activity, while the wt hexamer can accommodate two mutant subunits that hydrolyze ATP in only one protein ring. Four subunits seem to build the functional cooperative unit, provided that one of the protein rings contains active nucleotide binding sites.

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Genetic Analysis Reveals Domain Interactions of Arabidopsis Hsp100/ClpB and Cooperation with the Small Heat Shock Protein Chaperone System

Cited by 100 publications

References 51 publications

Modulation of Nitrosative Stress byS-Nitrosoglutathione Reductase Is Critical for Thermotolerance and Plant Growth inArabidopsis

Modulation of Nitrosative Stress byS-Nitrosoglutathione Reductase Is Critical for Thermotolerance and Plant Growth inArabidopsis

Interplay between Heat Shock Proteins HSP101 and HSA32 Prolongs Heat Acclimation Memory Posttranscriptionally in Arabidopsis

Nucleotide utilization requirements that render ClpB active as a chaperone

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