receiver domain Dotaz Zobrazit nápovědu
Multistep phosphorelay (MSP) cascades mediate responses to a wide spectrum of stimuli, including plant hormonal signaling, but several aspects of MSP await elucidation. Here, we provide first insight into the key step of MSP-mediated phosphotransfer in a eukaryotic system, the phosphorylation of the receiver domain of the histidine kinase CYTOKININ-INDEPENDENT 1 (CKI1RD) from Arabidopsis thaliana We observed that the crystal structures of free, Mg2+-bound, and beryllofluoridated CKI1RD (a stable analogue of the labile phosphorylated form) were identical and similar to the active state of receiver domains of bacterial response regulators. However, the three CKI1RD variants exhibited different conformational dynamics in solution. NMR studies revealed that Mg2+ binding and beryllofluoridation alter the conformational equilibrium of the β3-α3 loop close to the phosphorylation site. Mutations that perturbed the conformational behavior of the β3-α3 loop while keeping the active-site aspartate intact resulted in suppression of CKI1 function. Mechanistically, homology modeling indicated that the β3-α3 loop directly interacts with the ATP-binding site of the CKI1 histidine kinase domain. The functional relevance of the conformational dynamics observed in the β3-α3 loop of CKI1RD was supported by a comparison with another A. thaliana histidine kinase, ETR1. In contrast to the highly dynamic β3-α3 loop of CKI1RD, the corresponding loop of the ETR1 receiver domain (ETR1RD) exhibited little conformational exchange and adopted a different orientation in crystals. Biochemical data indicated that ETR1RD is involved in phosphorylation-independent signaling, implying a direct link between conformational behavior and the ability of eukaryotic receiver domains to participate in MSP.
- MeSH
- Arabidopsis enzymologie genetika MeSH
- krystalografie rentgenová MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- proteinkinasy chemie genetika MeSH
- proteinové domény MeSH
- proteiny huseníčku chemie genetika MeSH
- receptory buněčného povrchu chemie genetika MeSH
- sekundární struktura proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Multistep phosphorelay (MSP) signaling mediates responses to a variety of important stimuli in plants. In Arabidopsis MSP, the signal is transferred from sensor histidine kinase (HK) via histidine phosphotransfer proteins (AHP1-AHP5) to nuclear response regulators. In contrast to ancestral two-component signaling in bacteria, protein interactions in plant MSP are supposed to be rather nonspecific. Here, we show that the C-terminal receiver domain of HK CKI1 (CKI1(RD) ) is responsible for the recognition of CKI1 downstream signaling partners, and specifically interacts with AHP2, AHP3 and AHP5 with different affinities. We studied the effects of Mg²⁺, the co-factor necessary for signal transduction via MSP, and phosphorylation-mimicking BeF₃⁻ on CKI1(RD) in solution, and determined the crystal structure of free CKI1(RD) and CKI1(RD) in a complex with Mg²⁺. We found that the structure of CKI1(RD) shares similarities with the only known structure of plant HK, ETR1(RD) , with the main differences being in loop L3. Magnesium binding induces the rearrangement of some residues around the active site of CKI1(RD) , as was determined by both X-ray crystallography and NMR spectroscopy. Collectively, these results provide initial insights into the nature of molecular mechanisms determining the specificity of MSP signaling and MSP catalysis in plants.
- MeSH
- Arabidopsis enzymologie genetika fyziologie MeSH
- fosforylace MeSH
- fosfotransferasy genetika metabolismus MeSH
- histidin metabolismus MeSH
- krystalografie rentgenová MeSH
- mapování interakce mezi proteiny MeSH
- molekulární modely MeSH
- mutace MeSH
- proteinkinasy chemie genetika izolace a purifikace metabolismus MeSH
- proteiny huseníčku chemie genetika izolace a purifikace metabolismus MeSH
- rekombinantní fúzní proteiny MeSH
- senzitivita a specificita MeSH
- signální transdukce fyziologie MeSH
- terciární struktura proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Immunodetection is a powerful tool in functional studies of all organisms. In plants, the gene redundancy and presence of gene families composed of highly homologous members often impedes the unambiguous identification of individual gene products. A family of eight sensor histidine kinases (HKs) mediates the transduction of diverse signals into Arabidopsis thaliana cells, thereby ensuring the initiation of appropriate adaptive responses. Antibodies recognizing specific members of the HK family would be valuable for studying their functions in Arabidopsis and other plant species including important crops. We have focused on developing and applying antibodies against CYTOKININ-INDEPENDENT 1 (CKI1), which encodes a constitutively active membrane-bound sensor HK that regulates the development of female gametophytes and vascular tissue in Arabidopsis. A coding sequence delimiting the C-terminal receiver domain of CKI1 (CKI1(RD)) was expressed in Escherichia coli using the IPTG-inducible expression system and purified to give a highly pure target protein. The purified CKI1(RD) protein was then used as an antigen for anti-CKI1(RD) antibody production. The resulting polyclonal antibodies had a detection limit of 10 ng of target protein at 1:20,000 dilution and were able to specifically distinguish CKI1, both in vitro and in situ, even in a direct comparison with highly homologous members of the same HK family AHK4, CKI2 and ETR1. Finally, anti-CKI1(RD) antibodies were able to selectively bind CKI1-GFP fusion protein in a pull-down assay using crude lysate from an Arabidopsis cell suspension culture. Our results suggest that the receiver domain is a useful target for the functional characterization of sensor HKs in immunological and biochemical studies.
- MeSH
- Arabidopsis cytologie enzymologie MeSH
- imunoprecipitace MeSH
- molekulární sekvence - údaje MeSH
- proteinkinasy chemie imunologie izolace a purifikace metabolismus MeSH
- proteiny huseníčku chemie imunologie izolace a purifikace metabolismus MeSH
- protilátky imunologie MeSH
- sekvence aminokyselin MeSH
- signální transdukce MeSH
- specificita protilátek MeSH
- terciární struktura proteinů MeSH
- transport proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- financování organizované MeSH
- Publikační typ
- abstrakty MeSH
Sequence dependence of (13) C and (15) N chemical shifts in the receiver domain of CKI1 protein from Arabidopsis thaliana, CKI1RD , and its complexed form, CKI1RD •Mg(2+), was studied by means of MD/DFT calculations. MD simulations of a 20-ns production run length were performed. Nine explicitly hydrated structures of increasing complexity were explored, up to a 40-amino-acid structure. The size of the model necessary depended on the type of nucleus, the type of amino acid and its sequence neighbors, other spatially close amino acids, and the orientation of amino acid NH groups and their surface/interior position. Using models covering a 10 and a 15 Å environment of Mg(2+), a semi-quantitative agreement has been obtained between experiment and theory for the V67-I73 sequence. The influence of Mg(2+) binding was described better by the 15 Å as compared to the 10 Å model. Thirteen chemical shifts were analyzed in terms of the effect of Mg(2+) insertion and geometry preparation. The effect of geometry was significant and opposite in sign to the effect of Mg(2+) binding. The strongest individual effects were found for (15) N of D70, S74, and V68, where the electrostatics dominated; for (13) Cβ of D69 and (15) N of K76, where the influences were equal, and for (13) Cα of F72 and (13) Cβ of K76, where the geometry adjustment dominated. A partial correlation between dominant geometry influence and torsion angle shifts upon the coordination has been observed.
- MeSH
- hořčík chemie MeSH
- izotopy dusíku chemie MeSH
- izotopy uhlíku chemie MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- proteinkinasy chemie MeSH
- proteinové domény MeSH
- proteiny huseníčku chemie MeSH
- simulace molekulární dynamiky MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, tyrosine kinase inhibitor (TKI) therapy may select for drug-resistant BCR-ABL mutants. We used an ultra-deep sequencing (UDS) approach to resolve qualitatively and quantitatively the complexity of mutated populations surviving TKIs and to investigate their clonal structure and evolution over time in relation to therapeutic intervention. To this purpose, we performed a longitudinal analysis of 106 samples from 33 patients who had received sequential treatment with multiple TKIs and had experienced sequential relapses accompanied by selection of 1 or more TKI-resistant mutations. We found that conventional Sanger sequencing had misclassified or underestimated BCR-ABL mutation status in 55% of the samples, where mutations with 1% to 15% abundance were detected. A complex clonal texture was uncovered by clonal analysis of samples harboring multiple mutations and up to 13 different mutated populations were identified. The landscape of these mutated populations was found to be highly dynamic. The high degree of complexity uncovered by UDS indicates that conventional Sanger sequencing might be an inadequate tool to assess BCR-ABL kinase domain mutation status, which currently represents an important component of the therapeutic decision algorithms. Further evaluation of the clinical usefulness of UDS-based approaches is warranted.
- MeSH
- bcr-abl fúzové proteiny genetika chemie MeSH
- chemorezistence genetika MeSH
- dospělí MeSH
- inhibitory proteinkinas MeSH
- katalytická doména genetika MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mutační analýza DNA metody MeSH
- retrospektivní studie MeSH
- tyrosinkinasy MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
BACKGROUND AND OBJECTIVE: The availability of different tyrosine kinase inhibitors (TKIs) with distinct anti-leukemic potency enables optimization of current therapeutic regimens; however, some patients lose their therapy response and acquire TKI resistance. In this study, we describe a single-center experience of monitoring BCR-ABL1 kinase domain (KD) mutations and discuss the impact of treatment on mutation selection. METHODS: Chronic myelogenous leukemia (CML) patients treated with TKIs at the Department of Internal Medicine-Hematology and Oncology, Masaryk University and University Hospital Brno during 2003-2011 were included in this study. A total number of 100 patients who did not achieve an optimal therapy response or who lost their therapy response were screened for the presence of BCR-ABL1 KD mutations, using direct sequencing. RESULTS: Our data show that pretreatment with non-specific non-TKI drugs prior to TKI therapy does not preferentially select for initial BCR-ABL1 KD mutations, in contrast to first-line imatinib therapy, which shows a clear predominance of T315I or P-loop mutations compared with mutations located in other KD regions. In addition, the median time to detection of P-loop mutations was substantially shorter in patients treated with first-line imatinib than in those pretreated with non-TKI drugs. Furthermore, analysis of CML patients who had recurrent resistance to TKI therapy revealed possible therapy-driven selection of BCR-ABL1 KD mutations. Finally, we confirm the previously described poor prognosis of CML patients with mutations in the BCR-ABL1 KD, since 40.0% of our CML patients who harbored a BCR-ABL1 KD mutation died from CML while receiving TKI treatment. Moreover, among the patients who are still on treatment, 27.8% have already progressed. Our data also confirm the unique position of the T315I mutation with respect to its strong resistance to currently approved TKIs. CONCLUSION: On the basis of the 'real-life' data described in this study, it is possible that the therapy itself results in its failure and selects the most resistant mutations under the selective pressure of the applied therapy regimen in some CML patients who harbor BCR-ABL1 KD mutations.
- MeSH
- antitumorózní látky terapeutické užití MeSH
- bcr-abl fúzové proteiny genetika MeSH
- chronická myeloidní leukemie farmakoterapie genetika MeSH
- dospělí MeSH
- inhibitory proteinkinas terapeutické užití MeSH
- lidé středního věku MeSH
- lidé MeSH
- mutace MeSH
- senioři MeSH
- tyrosinkinasy genetika MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: The research is focused on sensitive biomarkers in multiple sclerosis (MS). OBJECTIVE: The aim of the study was to assess the relationship between plasma neurofilament light chain (pNfL) and disease activity as defined by the concept NEDA (no evident disease activity), including brain volumetry, in a cohort of MS patients treated with disease-modifying treatment (DMT). METHODS: Levels of pNfL (Single Molecule Array (SIMOA) technology) were examined in 95 RRMS (relapsing-remitting multiple sclerosis) patients and analyzed in relationship to NEDA-3 status and NEDA-BVL (brain volume loss; NEDA-3 extended by brain volumetry) during the last 12 months. The statistical model was developed using logistic regression analysis, including the independent variables: demographic, clinical, and magnetic resonance imaging (MRI) data. Dependent variables were NEDA-3 and NEDA-BVL status. RESULTS: The mean age of the study participants (n = 95, 62% females) was 37.85 years (standard deviation (SD) = 9.62) and the median disability score was 3.5 (2.5-4.1). Receiver operating characteristics (ROC) analysis showed that pNfL predicts NEDA-3 (the sensitivity and specificity of the model were 92% and 78%, respectively, p < 0.001) and NEDA-BVL status (the sensitivity and specificity were 80% and 65%, respectively, p < 0.001). CONCLUSION: The results show that pNfL levels are a useful biomarker of disease activity determined by NEDA-BVL status, including brain MRI-volumetry in patients with RRMS.
- MeSH
- dospělí MeSH
- intermediární filamenta MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- mozek diagnostické zobrazování MeSH
- relabující-remitující roztroušená skleróza * diagnostické zobrazování MeSH
- roztroušená skleróza * diagnostické zobrazování MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Immunotherapy and targeted therapy are currently two alternative backbones in the therapy of BRAF-mutated malignant melanoma. However, predictive biomarkers that would help with treatment selection are lacking. METHODS: This retrospective study investigated outcomes of anti-programmed death receptor-1 monotherapy and targeted therapy in the first-line setting in patients with metastatic BRAF-mutated melanoma, focusing on clinical and laboratory parameters associated with treatment outcome. RESULTS: Data from 174 patients were analysed. The median progression-free survival (PFS) was 17.0 months (95% CI; 8-39) and 12.5 months (95% CI; 9-14.2) for immunotherapy and targeted therapy, respectively. The 3-year PFS rate was 39% for immunotherapy and 25% for targeted therapy. The objective response rate was 72% and 51% for targeted therapy and immunotherapy. The median overall (OS) survival for immunotherapy has not been reached and was 23.6 months (95% CI; 16.1-38.2) for targeted therapy, with a 3-year survival rate of 63% and 40%, respectively. In a univariate analysis, age < 70 years, a higher number of metastatic sites, elevated serum LDH and a neutrophil-lymphocyte ratio above the cut-off value were associated with inferior PFS regardless of the therapy received, but only serum LDH level and the presence of lung metastases remained significant predictors of PFS in a multivariate analysis. CONCLUSIONS: Present real-world data document the high effectiveness of immunotherapy and targeted therapy. Although targeted therapy had higher response rates, immunotherapy improved PFS and OS. While the prognostic value of LDH was confirmed, the potential use of blood cell count-derived parameters to predict outcomes needs further investigation.
