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1.
Plant J ; 119(1): 237-251, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38597817

RESUMEN

Plasma membrane (PM)-associated abscisic acid (ABA) signal transduction is an important component of ABA signaling. The C2-domain ABA-related (CAR) proteins have been reported to play a crucial role in recruiting ABA receptor PYR1/PYL/RCAR (PYLs) to the PM. However, the molecular details of the involvement of CAR proteins in membrane-delimited ABA signal transduction remain unclear. For instance, where this response process takes place and whether any additional members besides PYL are taking part in this signaling process. Here, the GUS-tagged materials for all Arabidopsis CAR members were used to comprehensively visualize the extensive expression patterns of the CAR family genes. Based on the representativeness of CAR1 in response to ABA, we determined to use it as a target to study the function of CAR proteins in PM-associated ABA signaling. Single-particle tracking showed that ABA affected the spatiotemporal dynamics of CAR1. The presence of ABA prolonged the dwell time of CAR1 on the membrane and showed faster lateral mobility. Surprisingly, we verified that CAR1 could directly recruit hypersensitive to ABA1 (HAB1) and SNF1-related protein kinase 2.2 (SnRK2.2) to the PM at both the bulk and single-molecule levels. Furthermore, PM localization of CAR1 was demonstrated to be related to membrane microdomains. Collectively, our study revealed that CARs recruited the three main components of ABA signaling to the PM to respond positively to ABA. This study deepens our understanding of ABA signal transduction.


Asunto(s)
Ácido Abscísico , Proteínas de Arabidopsis , Arabidopsis , Membrana Celular , Proteínas Serina-Treonina Quinasas , Transducción de Señal , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Ácido Abscísico/metabolismo , Arabidopsis/metabolismo , Arabidopsis/genética , Membrana Celular/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Regulación de la Expresión Génica de las Plantas , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas Modificadas Genéticamente
2.
Plant Physiol ; 2024 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-38850036

RESUMEN

Water transportation to developing tissues relies on the structure and function of plant xylem cells. Plant microtubules govern the direction of cellulose microfibrils and guide secondary cell wall formation and morphogenesis. However, the relevance of microtubule-determined xylem wall thickening patterns in plant hydraulic conductivity remains unclear. In the present study, we identified a maize (Zea mays) semi-dominant mutant, designated drought-overly-sensitive1 (ZmDos1), the upper leaves of which wilted even when exposed to well-watered conditions during growth; the wilting phenotype was aggravated by increased temperatures and decreased humidity. Protoxylem vessels in the stem and leaves of the mutant showed altered thickening patterns of the secondary cell wall (from annular to spiral), decreased inner diameters, and limited water transport efficiency. The causal mutation for this phenotype was found to be a G-to-A mutation in the maize gene α-tubulin4, resulting in a single amino acid substitution at position 196 (E196K). Ectopic expression of the mutant α-tubulin4 in Arabidopsis (Arabidopsis thaliana) changed the orientation of microtubule arrays, suggesting a determinant role of this gene in microtubule assembly and secondary cell wall thickening. Our findings suggest that the spiral wall thickenings triggered by the α-tubulin mutation are stretched during organ elongation, causing a smaller inner diameter of the protoxylem vessels and affecting water transport in maize. This study underscores the importance of tubulin-mediated protoxylem wall thickening in regulating plant hydraulics, improves our understanding of the relationships between protoxylem structural features and functions, and offers candidate genes for the genetic enhancement of maize.

3.
Biochem Biophys Res Commun ; 714: 149956, 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38663095

RESUMEN

BACKGROUND: Maize is a major cereal crop world widely, however, the yield of maize is frequently limited by dehydration and even death of plants, which resulted from osmotic stress such as drought and salinity. Dissection of molecular mechanisms controlling stress tolerance will enable plant scientists and breeders to increase crops yield by manipulating key regulatory components. METHODS: The candidate OSR1 gene was identified by map-based cloning. The expression level of OSR1 was verified by qRT-PCR and digital PCR in WT and osr1 mutant. Electrophoretic mobility shift assay, transactivation activity assay, subcellular localization, transcriptome analysis and physiological characters measurements were conducted to analyze the function of OSR1 in osmotic stress resistance in maize. RESULTS: The osr1 mutant was significantly less sensitive to osmotic stress than the WT plants and displayed stronger water-holding capacity, and the OSR1 homologous mutant in Arabidopsis showed a phenotype similar with maize osr1 mutant. Differentially expressed genes (DEGs) were identified between WT and osr1 under osmotic stress by transcriptome analysis, the expression levels of many genes, such as LEA, auxin-related factors, PPR family members, and TPR family members, changed notably, which may primarily involve in osmotic stress or promote root development. CONCLUSIONS: OSR1 may serve as a negative regulatory factor in response to osmotic stress in maize. The present study sheds new light on the molecular mechanisms of osmotic stress in maize.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Presión Osmótica , Proteínas de Plantas , Factores de Transcripción , Zea mays , Zea mays/genética , Zea mays/metabolismo , Zea mays/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Mutación , Estrés Fisiológico/genética , Perfilación de la Expresión Génica
4.
Nucleic Acids Res ; 50(21): 12344-12354, 2022 11 28.
Artículo en Inglés | MEDLINE | ID: mdl-36477372

RESUMEN

5-Methyl-cytosine (5mC) is one of the most important DNA modifications and plays versatile biological roles. It is well known that 5mC stabilizes DNA duplexes. However, it remains unclear how 5mC affects the kinetics of DNA melting and hybridization. Here, we studied the kinetics of unzipping and rezipping using a 502-bp DNA hairpin by single-molecule magnetic tweezers. Under constant loading rates, 5mC increases the unzipping force but counterintuitively decreases the rezipping force at various salt and temperature conditions. Under constant forces, the non-methylated DNA hops between metastable states during unzipping and rezipping, which implies low energy barriers. Surprisingly, the 5mC DNA can't rezip after fully unzipping unless much lower forces are applied, where it rezips stochastically in a one-step manner, which implies 5mC kinetically hinders DNA hybridization and high energy barriers in DNA hybridization. All-atom molecular dynamics simulations reveal that the 5mC kinetically hinders DNA hybridization due to steric effects rather than electrostatic effects caused by the additional methyl groups of cytosines. Considering the possible high speed of DNA unzipping and zipping during replication and transcription, our findings provide new insights into the biological roles of 5mC.


Asunto(s)
5-Metilcitosina , ADN , Citosina , ADN/química , Fenómenos Magnéticos , Conformación de Ácido Nucleico , Hibridación de Ácido Nucleico
5.
Proc Natl Acad Sci U S A ; 118(25)2021 06 22.
Artículo en Inglés | MEDLINE | ID: mdl-34140406

RESUMEN

Single-stranded DNA (ssDNA) covered with the heterotrimeric Replication Protein A (RPA) complex is a central intermediate of DNA replication and repair. How RPA is regulated to ensure the fidelity of DNA replication and repair remains poorly understood. Yeast Rtt105 is an RPA-interacting protein required for RPA nuclear import and efficient ssDNA binding. Here, we describe an important role of Rtt105 in high-fidelity DNA replication and recombination and demonstrate that these functions of Rtt105 primarily depend on its regulation of RPA. The deletion of RTT105 causes elevated spontaneous DNA mutations with large duplications or deletions mediated by microhomologies. Rtt105 is recruited to DNA double-stranded break (DSB) ends where it promotes RPA assembly and homologous recombination repair by gene conversion or break-induced replication. In contrast, Rtt105 attenuates DSB repair by the mutagenic single-strand annealing or alternative end joining pathway. Thus, Rtt105-mediated regulation of RPA promotes high-fidelity replication and recombination while suppressing repair by deleterious pathways. Finally, we show that the human RPA-interacting protein hRIP-α, a putative functional homolog of Rtt105, also stimulates RPA assembly on ssDNA, suggesting the conservation of an Rtt105-mediated mechanism.


Asunto(s)
Reparación del ADN , Replicación del ADN , Proteínas de Unión al ARN/metabolismo , Proteína de Replicación A/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Transporte Activo de Núcleo Celular , Proteínas Portadoras/metabolismo , Núcleo Celular/metabolismo , Roturas del ADN de Doble Cadena , ADN de Cadena Simple/metabolismo , Conversión Génica , Eliminación de Gen , Duplicación de Gen , Humanos , Modelos Biológicos , Unión Proteica , Recombinasa Rad51/metabolismo
6.
Int J Mol Sci ; 25(12)2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38928126

RESUMEN

Photodynamic Therapy (PDT) is recognized for its exceptional effectiveness as a promising cancer treatment method. However, it is noted that overexposure to the dosage and sunlight in traditional PDT can result in damage to healthy tissues, due to the low tumor selectivity of currently available photosensitizers (PSs). To address this challenge, we introduce herein a new strategy where the small molecule-targeted agent, erlotinib, is integrated into a boron dipyrromethene (BODIPY)-based PS to form conjugate 6 to enhance the precision of PDT. This conjugate demonstrates optical absorption, fluorescence emission, and singlet oxygen generation efficiency comparable to the reference compound 7, which lacks erlotinib. In vitro studies reveal that, after internalization, conjugate 6 predominantly accumulates in the lysosomes of HepG2 cells, exhibiting significant photocytotoxicity with an IC50 value of 3.01 µM. A distinct preference for HepG2 cells over HELF cells is observed with conjugate 6 but not with compound 7. In vivo experiments further confirm that conjugate 6 has a specific affinity for tumor tissues, and the combination treatment of conjugate 6 with laser illumination can effectively eradicate H22 tumors in mice with outstanding biosafety. This study presents a novel and potential PS for achieving precise PDT against cancer.


Asunto(s)
Clorhidrato de Erlotinib , Neoplasias Hepáticas , Fotoquimioterapia , Fármacos Fotosensibilizantes , Porfobilinógeno , Humanos , Fotoquimioterapia/métodos , Animales , Ratones , Porfobilinógeno/análogos & derivados , Porfobilinógeno/química , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/química , Células Hep G2 , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/patología , Clorhidrato de Erlotinib/farmacología , Clorhidrato de Erlotinib/química , Compuestos de Boro/química , Compuestos de Boro/farmacología
7.
J Biol Chem ; 298(12): 102670, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36334628

RESUMEN

I-motifs are four-strand noncanonical secondary structures formed by cytosine (C)-rich sequences in living cells. The structural dynamics of i-motifs play essential roles in many cellular processes, such as telomerase inhibition, DNA replication, and transcriptional regulation. In cells, the structural dynamics of the i-motif can be modulated by the interaction of poly(C)-binding proteins (PCBPs), and the interaction is closely related to human health, through modulating the transcription of oncogenes and telomere stability. Therefore, the mechanisms of how PCBPs interact with i-motif structures are fundamentally important. However, the underlying mechanisms remain elusive. I-motif structures in the promoter of the c-MYC oncogene can be unfolded by heterogeneous nuclear ribonucleoprotein K (hnRNP K), a PCBP, to activate its transcription. Here, we selected this system as an example to comprehensively study the unfolding mechanisms. We found that the promoter sequence containing 5 C-runs preferred folding into type-1245 to type-1234 i-motif structures based on their folding stability, which was further confirmed by single-molecule FRET. In addition, we first revealed that the c-MYC i-motif structure was discretely resolved by hnRNP K through two intermediate states, which were assigned to the opposite hairpin and neighboring hairpin, as further confirmed by site mutations. Furthermore, we found all three KH (hnRNP K homology) domains of hnRNP K could unfold the c-MYC i-motif structure, and KH2 and KH3 were more active than KH1. In conclusion, this study may deepen our understanding of the interactions between i-motifs and PCBPs and may be helpful for drug development.


Asunto(s)
Proteínas Portadoras , Ribonucleoproteína Heterogénea-Nuclear Grupo K , Humanos , Ribonucleoproteína Heterogénea-Nuclear Grupo K/genética , Ribonucleoproteína Heterogénea-Nuclear Grupo K/metabolismo , Proteínas Portadoras/metabolismo , Proteínas de Unión al ARN/metabolismo , ADN/metabolismo , Estructura Secundaria de Proteína
8.
J Biol Chem ; 298(8): 102165, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35738400

RESUMEN

RNA G-quadruplexes (rG4s) are noncanonical RNA secondary structures formed by guanine (G)-rich sequences. These complexes play important regulatory roles in both animals and plants through their structural dynamics and are closely related to human diseases and plant growth, development, and adaption. Thus, studying the structural dynamics of rG4s is fundamentally important; however, their folding pathways and their unfolding by specialized helicases are not well understood. In addition, no plant rG4-specialized helicases have been identified. Here, using single-molecule FRET, we experimentally elucidated for the first time the folding pathway and intermediates, including a G-hairpin and G-triplex. In addition, using proteomics screening and microscale thermophoresis, we identified and validated five rG4-specialized helicases in Arabidopsis thaliana. Furthermore, DExH1, the ortholog of the famous human rG4 helicase RHAU/DHX36, stood out for its robust rG4 unwinding ability. Taken together, these results shed light on the structural dynamics of plant rG4s.


Asunto(s)
G-Cuádruplex , Animales , Catálisis , ARN Helicasas DEAD-box/metabolismo , ADN Helicasas/metabolismo , Humanos , ARN/metabolismo
9.
J Am Chem Soc ; 145(17): 9464-9470, 2023 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-37079381

RESUMEN

Given the wide availability and low cost of alkylbenzenes, direct C-H functionalization of these aromatic hydrocarbons to afford structurally complex building blocks has long been of interest in organic synthesis. Herein we describe a method for rhodium-catalyzed dehydrogenative (3 + 2) cycloaddition reactions of alkylbenzenes with 1,1-bis(phenylsulfonyl)ethylene. The π-coordination with a rhodium catalyst facilitates the benzylic deprotonation, allowing for the subsequent (3 + 2) cycloaddition in which the metal-complexed carbanion serves as a unique all-carbon 1,3-dipole equivalent. We demonstrated the generality of this catalytic method by carrying out reactions of a large array of alkylbenzenes to generate dihydroindene derivatives bearing two synthetically versatile sulfonyl groups. Quantum-chemical calculations revealed details of the reaction process.

10.
Small ; 19(27): e2300364, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36987976

RESUMEN

Cesium copper halide perovskite is one of the promising materials for solar-blind light detection. However, most of the cesium copper halide perovskite-based photodetectors (PDs) are focused on ultraviolet A detection and realized on the rigid substrate in the single device configuration. Here, a flexible solar-blind PDs array (10 × 10 pixels) based on the CsCu2 I3 film patterns for ultraweak light sensing and light distribution imaging is reported. Large-scale CsCu2 I3 film arrays are synthesized with various shapes and uniform dimensions through a simple vacuum-heating-assisted solution method. Benefiting from excellent air stability and superior resistance to the photodegrading of the CsCu2 I3 film, the array device exhibits long-term stable photoswitching behavior for 8 h and ultralow light detection capability to resolve the light intensity of 6.1 nW cm-2 with a high responsivity of 62 A W-1 , and the array device can acquire clear images of "G", "X", and "U" showing the input light distribution. Moreover, the flame detection and warning system based on a curved solar-blind PDs array is demonstrated, which can be used for multi-flame monitoring and locating. These results can encourage potential applications of the CsCu2 I3 film-based PDs array in the field of optical communication and environment monitoring.

11.
J Org Chem ; 88(20): 14264-14273, 2023 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-37811870

RESUMEN

Intermolecular (3 + 2) annulation emerges as a potent approach for constructing 5-membered carbocycles through the fusion of two distinct components. This synopsis encapsulates recent strides in the realm of transition-metal-catalyzed dehydrogenative (3 + 2) annulation of aromatic hydrocarbons, achieved through the dual functionalization of benzylic and ortho C-H bonds. Encompassing three pivotal strategies, namely, (i) C-H bond activation, (ii) benzylic oxidation, and (iii) π-coordination activation, this review offers an overview of the field's recent developments.

12.
BMC Genomics ; 23(1): 499, 2022 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-35810309

RESUMEN

BACKGROUND: The trihelix family of transcription factors plays essential roles in the growth, development, and abiotic stress response of plants. Although several studies have been performed on the trihelix gene family in several dicots and monocots, this gene family is yet to be studied in Chenopodium quinoa (quinoa). RESULTS: In this study, 47 C. quinoa trihelix (CqTH) genes were in the quinoa genome. Phylogenetic analysis of the CqTH and trihelix genes from Arabidopsis thaliana and Beta vulgaris revealed that the genes were clustered into five subfamilies: SIP1, GTγ, GT1, GT2, and SH4. Additionally, synteny analysis revealed that the CqTH genes were located on 17 chromosomes, with the exception of chromosomes 8 and 11, and 23 pairs of segmental duplication genes were detected. Furthermore, expression patterns of 10 CqTH genes in different plant tissues and at different developmental stages under abiotic stress and phytohormone treatment were examined. Among the 10 genes, CqTH02, CqTH25, CqTH18, CqTH19, CqTH25, CqTH31, and CqTH36, were highly expressed in unripe achenes 21 d after flowering and in mature achenes compared with other plant tissues. Notably, the 10 CqTH genes were upregulated in UV-treated leaves, whereas CqTH36 was consistently upregulated in the leaves under all abiotic stress conditions. CONCLUSIONS: The findings of this study suggest that gene duplication could be a major driver of trihelix gene evolution in quinoa. These findings could serve as a basis for future studies on the roles of CqTH transcription factors and present potential genetic markers for breeding stress-resistant and high-yielding quinoa varieties.


Asunto(s)
Arabidopsis , Chenopodium quinoa , Arabidopsis/genética , Chenopodium quinoa/genética , Chenopodium quinoa/metabolismo , Regulación de la Expresión Génica de las Plantas , Filogenia , Fitomejoramiento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estrés Fisiológico/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
13.
J Am Chem Soc ; 144(3): 1144-1151, 2022 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-35015956

RESUMEN

Given the wide prevalence and ready availability of both phenols and amines, aniline synthesis through direct coupling between these starting materials would be extremely attractive. Herein, we describe a rhodium-catalyzed amination of phenols, which provides concise access to diverse anilines, with water as the sole byproduct. The arenophilic rhodium catalyst facilitates the inherently difficult keto-enol tautomerization of phenols by means of π-coordination, allowing for the subsequent dehydrative condensation with amines. We demonstrate the generality of this redox-neutral catalysis by carrying out reactions of a large array of phenols with various electronic properties and a wide variety of primary and secondary amines. Several examples of late-stage functionalization of structurally complex bioactive molecules, including pharmaceuticals, further illustrate the potential broad utility of the method.

14.
Antimicrob Agents Chemother ; 66(5): e0009422, 2022 05 17.
Artículo en Inglés | MEDLINE | ID: mdl-35404074

RESUMEN

GST-HG131, a novel dihydroquinolizinone (DHQ) compound, has been shown to reduce circulating levels of HBsAg in animals. This first-in-human trial evaluated the safety, tolerability, and pharmacokinetic profile of GST-HG131 in healthy Chinese subjects. This was a double-blind, randomized, placebo-controlled phase Ia clinical trial that was conducted in two parts. Part A was a single-ascending-dose (SAD; GST-HG131 10 30, 60, 100, 150, 200, 250 or 300 mg or placebo) study, which also assessed the food effect of GST-HG131 100 mg. Part B was a multiple-ascending-dose (MAD; GST-HG131 30, 60 or 100 mg or placebo BID) study. Tolerability assessments included adverse events, vital signs, 12-lead electrocardiogram, physical examination, and clinical laboratory tests. PK analyses were conducted in blood, urine, and fecal samples. Single doses of GST-HG131 ≤ 300 mg and multiple doses of GST-HG131 ≤ 60 mg were generally safe and well tolerated; however, multiple dosing was stopped at GST-HG131 100 mg, as pre-defined stopping rules specified in the protocol were met (Grade II drug related AEs of nausea and dizziness in >50% of subjects). In the SAD study, median tmax of GST-HG131 was 1-6 h, and t1/2 ranged from 3.88 h to 14.3 h. PK parameters were proportional to dose. Exposure was reduced after food intake. In the MAD study, steady-state was attained on day 4, and there was no apparent plasma accumulation of GST-HG131 on day 7 (Racc < 1.5). In conclusion, GST-HG131 exhibited an acceptable safety profile in healthy subjects at single doses ranging from 10-300 mg and multiple doses (BID) ranging from 30-60 mg, and the MAD doses (30 mg and 60 mg BID) that potentially meet the therapeutic AUC requirements. These findings imply GST-HG131 has potential as a therapeutic option for CHB infection. (This study has been registered at ClinicalTrials.gov under identifier NCT04499443.).


Asunto(s)
Virus de la Hepatitis B , Área Bajo la Curva , China , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Voluntarios Sanos , Humanos
15.
Bioorg Med Chem Lett ; 75: 128977, 2022 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-36089112

RESUMEN

Chronic hepatitis B (CHB) remains a significant health challenge worldwide. The current treatments for CHB achieve less than 10% cure rates, majority of the patients are on therapy for life. Therefore, cure of CHB is a high unmet medical need. HBV surface antigen (HBsAg) loss and seroconversion are considered as the key for the cure. RG7834 is a novel, orally bioavailable small molecule reported to reduce HBV antigens. Based on RG7834 chemistry, we designed and discovered a series of dihydrobenzopyridooxazepine (DBP) series of HBV antigen inhibitors. Extensive SAR studies led us to GST-HG131 with excellent reduction of HBV antigens (both HBsAg and HBeAg) in vitro and in vivo. GST-HG131 improved safety in rat toxicology studies over RG7834. The promising inhibitory activity, together with animal safety enhancement, merited GST-HG131 progressed into clinical development in 2020 (NCT04499443).


Asunto(s)
Hepatitis B Crónica , Hepatitis B , Animales , Ratas , Antígenos de Superficie , Antivirales/farmacología , Antivirales/uso terapéutico , ADN Viral , Hepatitis B/tratamiento farmacológico , Antígenos e de la Hepatitis B/uso terapéutico , Antígenos de Superficie de la Hepatitis B , Virus de la Hepatitis B , Hepatitis B Crónica/tratamiento farmacológico
16.
Angew Chem Int Ed Engl ; 61(35): e202207917, 2022 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-35767354

RESUMEN

The use of alkylarenes as nucleophile precursors in benzylic addition is challenging because the benzylic hydrogen atoms of these compounds are inert to deprotonation. Herein, we report Rh-catalyzed benzylic addition of alkylarenes to Michael acceptors for the formation of C(sp3 )-C(sp3 ) bonds. The catalyst is proposed to activate the aromatic ring via η6 -coordination, dramatically facilitating deprotonation of the unactivated benzylic C-H bond and addition of the resulting carbanion to the α,ß-unsaturated double bond in the absence of bases. Notably, this byproduct-free method provides an access to all-carbon quaternary centers through the development of ligands.

17.
Angew Chem Int Ed Engl ; 61(11): e202117381, 2022 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-35006640

RESUMEN

We report a convenient method for benzylic H/D exchange of a wide variety of substrates bearing primary, secondary, or tertiary C-H bonds via a reversible η6 -coordination strategy. A doubly cationic [CpCF3 RhIII ]2+ catalyst that serves as an arenophile facilitates deprotonation of inert benzylic hydrogen atoms (pKa >40 in DMSO) without affecting other hydrogen atoms, such as those on aromatic rings or in α-positions of carboxylate groups. Notably, the H/D exchange reactions feature high stereoretention. We demonstrated the potential utility of this method by using it for deuterium labeling of ten pharmaceuticals and their analogues.

18.
J Biol Chem ; 295(16): 5461-5469, 2020 04 17.
Artículo en Inglés | MEDLINE | ID: mdl-32184352

RESUMEN

Telomeres are specific nucleoprotein structures that are located at the ends of linear eukaryotic chromosomes and play crucial roles in genomic stability. Telomere DNA consists of simple repeats of a short G-rich sequence: TTAGGG in mammals and TTTAGGG in most plants. In recent years, the mammalian telomeric G-rich repeats have been shown to form G-quadruplex (G4) structures, which are crucial for modulating telomere functions. Surprisingly, even though plant telomeres are essential for plant growth, development, and environmental adaptions, only few reports exist on plant telomeric G4 DNA (pTG4). Here, using bulk and single-molecule assays, including CD spectroscopy, and single-molecule FRET approaches, we comprehensively characterized the structure and dynamics of a typical plant telomeric sequence, d[GGG(TTTAGGG)3]. We found that this sequence can fold into mixed G4s in potassium, including parallel and antiparallel structures. We also directly detected intermediate dynamic transitions, including G-hairpin, parallel G-triplex, and antiparallel G-triplex structures. Moreover, we observed that pTG4 is unfolded by the AtRecQ2 helicase but not by AtRecQ3. The results of our work shed light on our understanding about the existence, topological structures, stability, intermediates, unwinding, and functions of pTG4.


Asunto(s)
Cromosomas de las Plantas/genética , G-Cuádruplex , Telómero/química , Proteínas de Arabidopsis/metabolismo , Inestabilidad Genómica , RecQ Helicasas/metabolismo , Telómero/genética
19.
Antimicrob Agents Chemother ; 65(10): e0122021, 2021 09 17.
Artículo en Inglés | MEDLINE | ID: mdl-34280012

RESUMEN

Hepatitis B virus capsid assembly modulators (HBV CAMs) are promising, clinically validated therapeutic agents for the treatment of chronic hepatitis B (CHB). The safety, tolerability, and pharmacokinetic (PK) profiles of GST-HG141, a novel HBV CAM, were evaluated in healthy Chinese volunteers. This phase Ia study included two parts: a double-blinded, randomized, placebo-controlled single-ascending-dose (SAD) (50, 100, 200, 300, 400, or 500 mg) study comprising a food-effect investigation (300 mg) and a multiple-ascending-dose (MAD) (100 or 200 mg twice daily) study. GST-HG141 reached the maximum plasma concentration (Cmax) at 1.25 to 3.00 h (median Tmax). The exposure exhibited a linear increase, while the mean half-life (t1/2) ranged from 13.096 h to 22.121 h. The exposure of GST-HG141 (300 mg) was higher after food intake by about 2.4-fold. In the MAD study, steady state was reached at around day 5, and the mean trough steady-state concentrations were 423 and 588 ng/ml for 50- and 100-mg cohorts, respectively. The ratios of GST-HG141 accumulation were <1.5. GST-HG141 was well tolerated in healthy Chinese subjects. The rates of adverse events in the GST-HG141 cohort did not differ from those of the placebo cohort. GST-HG141 was tolerated in healthy Chinese subjects. The safety and PK profiles of GST-HG141 support the further evaluation of its efficacy in individuals with CHB. (This study has been registered in ClinicalTrials.gov under identifier NCT04536337.).


Asunto(s)
Virus de la Hepatitis B , Hepatitis B Crónica , Administración Oral , Área Bajo la Curva , Cápside , China , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Voluntarios Sanos , Virus de la Hepatitis B/genética , Hepatitis B Crónica/tratamiento farmacológico , Humanos
20.
Artículo en Inglés | MEDLINE | ID: mdl-34128783

RESUMEN

Strain HNM0947T, representing a novel actinobacterium, was isolated from the coral Galaxea astreata collected from the coast of Wenchang, Hainan, China. The strain was found to have morphological and chemotaxonomic characteristics consistent with the genus Nocardiopsis. The organism formed abundant fragmented substrate mycelia and aerial mycelia which differentiated into non-motile, rod-shaped spores. Whole-cell hydrolysates contained meso-diaminopimelic acid and no diagnostic sugars. The major menaquinones were MK-10(H8), MK-10(H6) and MK-10(H4). The major phospholipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were iso-C16:0, anteiso-C17:0, C18:0, C18:0 10-methyl (TBSA) and anteiso-C15:0. The G+C content was 71.3 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HNM0947T belonged to the genus Nocardiopsis and shared highest sequence similarity to Nocardiopsis salina YIM 90010T (98.8%), Nocardiopsis xinjiangensis YIM 90004T(98.5%) and Nocardiopsis kunsanensis DSM 44524T (98.3%). The strain HNM0947T was distinguished from its closest type strain by low average nucleotide identity (90.8%) and dDDH values (60.4%) respectively. Based on genotypic, chemotaxonomic and phenotypic characteristics, it was concluded that strain HNM0947T represents a novel species of the genus Nocardiopsis whose name was proposed as Nocardiopsis coralli sp. nov. The type strain was HNM0947T (=CCTCC AA 2020015 T=KCTC 49525 T).


Asunto(s)
Antozoos/microbiología , Nocardiopsis/clasificación , Filogenia , Animales , Técnicas de Tipificación Bacteriana , Composición de Base , China , ADN Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Grasos/química , Nocardiopsis/aislamiento & purificación , Hibridación de Ácido Nucleico , Fosfolípidos/química , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Vitamina K 2/química
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