Arabidopsis MPK4 and MPK6 are implicated in different signalling pathways responding to diverse external stimuli. This was recently correlated with transcriptomic profiles of Arabidopsis mpk4 and mpk6 mutants, and thus it should be reflected also on the level of constitutive proteomes. Therefore, we performed a shot gun comparative proteomic analysis of Arabidopsis mpk4 and mpk6 mutant roots. We have used bioinformatic tools and propose several new proteins as putative MPK4 and MPK6 phosphorylation targets. Among these proteins in the mpk6 mutant were important modulators of development such as CDC48A and phospholipase D alpha 1. In the case of the mpk4 mutant transcriptional reprogramming might be mediated by phosphorylation and change in the abundance of mRNA decapping complex VCS. Further comparison of mpk4 and mpk6 root differential proteomes showed differences in the composition and regulation of defense related proteins. The mpk4 mutant showed altered abundances of antioxidant proteins. The examination of catalase activity in response to oxidative stress revealed that this enzyme might be preferentially regulated by MPK4. Finally, we proposed developmentally important proteins as either directly or indirectly regulated by MPK4 and MPK6. These proteins contribute to known phenotypic defects in the mpk4 and mpk6 mutants.

• MeSH
• Arabidopsis enzymologie   genetika   MeSH
• fosforylace MeSH
• fyziologický stres MeSH
• genová ontologie MeSH
• genový knockout MeSH
• katalasa metabolismus   MeSH
• kořeny rostlin enzymologie   genetika   MeSH
• missense mutace MeSH
• mitogenem aktivované proteinkinasy genetika   MeSH
• peroxidasa metabolismus   MeSH
• posttranslační úpravy proteinů MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteom metabolismus   MeSH
• proteomika MeSH
• receptory pro aktivovanou kinasu C metabolismus   MeSH
• sekvence aminokyselin MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• srovnávací studie MeSH
• Názvy látek
• AtMPK4 protein, Arabidopsis MeSH Prohlížeč
• katalasa MeSH
• mitogenem aktivované proteinkinasy MeSH
• MPK6 protein, Arabidopsis MeSH Prohlížeč
• peroxidasa MeSH
• proteiny huseníčku MeSH
• proteom MeSH
• RACK1 protein, Arabidopsis MeSH Prohlížeč
• receptory pro aktivovanou kinasu C MeSH
• REM1 protein, Arabidopsis MeSH Prohlížeč

Plant cell growth and morphogenesis depend on remodelling of both actin and microtubule cytoskeletons. AtFH1 (At5g25500), the main housekeeping Arabidopsis formin, is targeted to membranes and known to nucleate and bundle actin. The effect of mutations in AtFH1 on root development and cytoskeletal dynamics was examined. Consistent with primarily actin-related formin function, fh1 mutants showed increased sensitivity to the actin polymerization inhibitor latrunculin B (LatB). LatB-treated mutants had thicker, shorter roots than wild-type plants. Reduced cell elongation and morphological abnormalities were observed in both trichoblasts and atrichoblasts. Fluorescently tagged cytoskeletal markers were used to follow cytoskeletal dynamics in wild-type and mutant plants using confocal microscopy and VAEM (variable-angle epifluorescence microscopy). Mutants exhibited more abundant but less dynamic F-actin bundles and more dynamic microtubules than wild-type seedlings. Treatment of wild-type seedlings with a formin inhibitor, SMIFH2, mimicked the root growth and cell expansion phenotypes and cytoskeletal structure alterations observed in fh1 mutants. The results suggest that besides direct effects on actin organization, the in vivo role of AtFH1 also includes modulation of microtubule dynamics, possibly mediated by actin-microtubule cross-talk.

• MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   MeSH
• forminy MeSH
• kořeny rostlin genetika   růst a vývoj   metabolismus   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• mikrofilamenta genetika   metabolismus   MeSH
• mikrotubuly genetika   metabolismus   MeSH
• mutace * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AFH1 protein, Arabidopsis MeSH Prohlížeč
• forminy MeSH
• membránové proteiny MeSH
• proteiny huseníčku MeSH

Gamma-tubulin is required for microtubule (MT) nucleation at MT organizing centers such as centrosomes or spindle pole bodies, but little is known about its noncentrosomal functions. We conditionally downregulated gamma-tubulin by inducible expression of RNA interference (RNAi) constructs in Arabidopsis thaliana. Almost complete RNAi depletion of gamma-tubulin led to the absence of MTs and was lethal at the cotyledon stage. After induction of RNAi expression, gamma-tubulin was gradually depleted from both cytoplasmic and microsomal fractions. In RNAi plants with partial loss of gamma-tubulin, MT recovery after drug-induced depolymerization was impaired. Similarly, immunodepletion of gamma-tubulin from Arabidopsis extracts severely compromised in vitro polymerization of MTs. Reduction of gamma-tubulin protein levels led to randomization and bundling of cortical MTs. This finding indicates that MT-bound gamma-tubulin is part of a cortical template guiding the microtubular network and is essential for MT nucleation. Furthermore, we found that cells with decreased levels of gamma-tubulin could progress through mitosis, but cytokinesis was strongly affected. Stepwise diminution of gamma-tubulin allowed us to reveal roles for MT nucleation in plant development, such as organization of cell files, anisotropic and polar tip growth, and stomatal patterning. Some of these functions of gamma-tubulin might be independent of MT nucleation.

• MeSH
• Arabidopsis anatomie a histologie   cytologie   metabolismus   MeSH
• buněčné jádro fyziologie   MeSH
• down regulace MeSH
• fenotyp MeSH
• kořeny rostlin cytologie   růst a vývoj   metabolismus   MeSH
• listy rostlin cytologie   růst a vývoj   metabolismus   MeSH
• mikrotubuly metabolismus   ultrastruktura   MeSH
• mitóza fyziologie   MeSH
• molekulární sekvence - údaje MeSH
• proteiny huseníčku genetika   fyziologie   MeSH
• RNA interference MeSH
• tubulin genetika   fyziologie   MeSH
• zvětšování buněk MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteiny huseníčku MeSH
• tubulin MeSH