RESUMO
Manganese and calcium homeostasis and signalling, in eukaryotic organisms, are regulated through membrane located pumps, channels and exchangers, including the Mn2+/Ca2+ uncharacterized protein family 0016 (UPF0016). Here we show that Plasmodiophora brassicae PbGDT1 is a member of the UPF0016 and an ortholog of Saccharomyces cerevisiae Gdt1p (GCR Dependent Translation Factor 1) protein involved in manganese homeostasis as well as the calcium mediated stress response in yeast. PbGDT1 complemented the ScGdt1p and ScPMR1 (Ca2+ ATPase) double null mutant under elevated calcium stress but not under elevated manganese conditions. In both yeast and Nicotiana benthamiana, PbGDT1 localizes to the Golgi apparatus, with additional ER association in N. benthamiana. Expression of PbGDT1 in N. benthamiana, suppresses BAX-triggered cell death, further highlighting the importance of calcium homeostasis in maintaining cell physiology and integrity in a stress environment.
Assuntos
Cálcio , Complexo de Golgi , Manganês , Nicotiana , Saccharomyces cerevisiae , Nicotiana/genética , Manganês/metabolismo , Cálcio/metabolismo , Complexo de Golgi/metabolismo , Complexo de Golgi/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Homeostase , ATPases Transportadoras de Cálcio/genética , ATPases Transportadoras de Cálcio/metabolismo , Transporte Biológico/genéticaRESUMO
We screened for endoplasmic reticulum (ER) stress-resistant mutants among 25 mutants of the Arabidopsis NTL (NAC with Transmembrane motif 1-Like) family. We identified a novel mutant, SALK_044777, showing strong resistance to ER stress. RT-PCR and genomic DNA sequence analyses identified the mutant as atntl7, which harbors a T-DNA insertion in the fourth exon of AtNTL7. Two other atntl7-mutant alleles, in which T-DNA was inserted in the second exon and third intron of AtNTL7, respectively, showed ER-stress sensitive phenotypes, suggesting that SALK_044777 is a gain-of-function mutant. Arabidopsis plants overexpressing AtNTL7 showed strong ER-stress resistance. Our findings suggest that AtNTL7 fragment is cleaved from the ER membrane under ER stress and translocates into the nucleus to induce downstream ER-stress responsive genes.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Estresse do Retículo Endoplasmático , Retículo Endoplasmático/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/genética , Fatores de Transcrição/genéticaRESUMO
To identify novel roles of SMALL RUBBER PARTICLE PROTEIN Homolog in the non-rubber-producing plant Arabidopsis (AtSRP1), we isolated a T-DNA-insertion knock-out mutant (FLAG_543A05) and investigated its functional characteristics. AtSRP1 is predominantly expressed in reproductive organs and is localized to lipid droplets and ER. Compared to wild-type (WT) Arabidopsis, atsrp1 plants contain small siliques with a reduced number of heterogeneously shaped seeds. The size of anther and pollen grains in atsrp1 is highly irregular, with a lower grain number than WT. Therefore, AtSRP1 plays a novel role related to pollen growth and development in a non-rubber-producing plant.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Pólen/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/análise , Proteínas de Arabidopsis/genética , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Técnicas de Inativação de Genes , Mutação , Pólen/genética , Pólen/metabolismo , Sementes/genética , Sementes/metabolismoRESUMO
Although a wide range of physiological information on Universal Stress Proteins (USPs) is available from many organisms, their biochemical, and molecular functions remain unidentified. The biochemical function of AtUSP (At3g53990) from Arabidopsis thaliana was therefore investigated. Plants over-expressing AtUSP showed a strong resistance to heat shock and oxidative stress, compared with wild-type and Atusp knock-out plants, confirming the crucial role of AtUSP in stress tolerance. AtUSP was present in a variety of structures including monomers, dimers, trimers, and oligomeric complexes, and switched in response to external stresses from low molecular weight (LMW) species to high molecular weight (HMW) complexes. AtUSP exhibited a strong chaperone function under stress conditions in particular, and this activity was significantly increased by heat treatment. Chaperone activity of AtUSP was critically regulated by the redox status of cells and accompanied by structural changes to the protein. Over-expression of AtUSP conferred a strong tolerance to heat shock and oxidative stress upon Arabidopsis, primarily via its chaperone function.
