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1.
Waste Manag ; 102: 939-948, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855694

RESUMO

With the purpose of developing a novel approach of agricultural waste treatment and overcoming bottlenecks for upscaling solid-state fermentation processes, the type of aerated, continuously stirred solid-state bioreactors were used for the production of γ-PGA by Bacillus amyloliquefaciens JX-6. Using corn stalk and soybean meal, the most common agricultural waste in China, as solid substrates, the maximum production of γ-PGA was 116.88 ± 5.05 g/kg and 102.48 ± 3.30 g/kg in 50 L and 150 L bioreactors, respectively. Production of γ-PGA in 50 L bioreactor was higher than in 150 L bioreactor, demonstrating that a reduction in γ-PGA production occurred as the fermentation system enlarged. An analysis of the interactions among fermentation parameters (temperature, moisture, and pH), γ-PGA production, solid substrates and bacterial communities indicated that different bioreactor capacities caused changes in fermentation parameters and bacterial communities, which in turn affected substrate utilization and γ-PGA production. Overall, obtaining considerable amounts of γ-PGA under non-sterilized fermentation expressed that JX-6 has excellent abilities to adapt to these substrates and conditions. Bioconversion of agricultural waste into γ-PGA in scale-up fermentation was successfully conducted by creating a more stable and suitable fermentation environment in bioreactors.


Assuntos
Reatores Biológicos , Ácido Poliglutâmico , China , Fermentação , Ácido Poliglutâmico/análogos & derivados
2.
Genesis ; : e23347, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31774613

RESUMO

Primordial germ cells (PGCs) are the precursors to the adult germline stem cells that are set aside early during embryogenesis and specified through the inheritance of the germ plasm, which contains the mRNAs and proteins that function as the germline fate determinants. In Drosophila melanogaster, formation of the PGCs requires the microtubule and actin cytoskeletal networks to actively segregate the germ plasm from the soma and physically construct the pole buds (PBs) that protrude from the posterior cortex. Of emerging importance is the central role of centrosomes in the coordination of microtubule dynamics and actin organization to promote PGC development. We previously identified a requirement for the centrosome protein Centrosomin (Cnn) in PGC formation. Cnn interacts directly with Pericentrin-like protein (PLP) to form a centrosome scaffold structure required for pericentriolar material recruitment and organization. In this study, we identify a role for PLP at several discrete steps during PGC development. We find PLP functions in segregating the germ plasm from the soma by regulating microtubule organization and centrosome separation. These activities further contribute to promoting PB protrusion and facilitating the distribution of germ plasm in proliferating PGCs.

3.
Bioresour Technol ; 293: 122066, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31557641

RESUMO

This work investigated the effects of different temperatures on methane production, kinetics, and microbial communities during solid-state anaerobic digestion (SS-AD) using rice straw. The results indicated that thermophilic anaerobic digestion led to the faster methane production (13.74 L/kg) and a shorter biogas production cycle (34 days) than mesophilic anaerobic digestion (5.48 L/kg, 58 days). SS-AD under thermophilic conditions resulted in more intense lignocellulose degradation and better fitting results. The species of microorganisms did not differ when the temperature was altered; however, the abundances of various phyla, particularly Firmicutes, differed. Overall, the findings suggested that thermophilic SS-AD had higher methanogenic efficiency and dramatically altered the structure of the microbial community during solid-state anaerobic digestion. Moreover, a potential effective strategy for agricultural waste management by SS-AD was proposed.


Assuntos
Biocombustíveis , Oryza , Anaerobiose , Reatores Biológicos , Metano , Temperatura Ambiente
4.
Genetics ; 213(3): 877-895, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31558581

RESUMO

Heterochromatin-mediated repression is essential for controlling the expression of transposons and for coordinated cell type-specific gene regulation. The small ovary (sov) locus was identified in a screen for female-sterile mutations in Drosophila melanogaster, and mutants show dramatic ovarian morphogenesis defects. We show that the null sov phenotype is lethal and map the locus to the uncharacterized gene CG14438, which encodes a nuclear zinc-finger protein that colocalizes with the essential Heterochromatin Protein 1 (HP1a). We demonstrate Sov functions to repress inappropriate gene expression in the ovary, silence transposons, and suppress position-effect variegation in the eye, suggesting a central role in heterochromatin stabilization.

5.
ACS Infect Dis ; 5(2): 177-183, 2019 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-30672289

RESUMO

Zika virus (ZIKV), a positive-strand RNA virus belonging to the Flavivirus genus, has become an urgent public health concern since recent outbreaks worldwide. Its genome replication is facilitated by the viral NS3 protein bearing helicase function. The NS3 helicase uses energy derived from adenosine triphosphate (ATP) hydrolysis to unwind RNA duplexed regions. Structural studies of the flavivirus NS3 helicases have suggested a conserved mechanism of ATP hydrolysis. However, the process of the reactant water replenishment, a key part of the hydrolysis cycle, remains elusive. Here, we report two high-resolution crystal structures of ZIKV NS3 helicase in complex with adenosine diphosphate (ADP) and Mn2+, one with the reactant water already loaded as previously observed and the other with the water molecule still in a loading state. These data suggest that the reactant water replenishment can occur between the release of phosphate and the release of ADP and improves the structural basis of the NS3 ATP hydrolysis cycle.


Assuntos
Trifosfato de Adenosina/química , Cristalografia por Raios X , Proteínas não Estruturais Virais/química , Água/química , Zika virus/química , Difosfato de Adenosina/química , Hidrólise , Modelos Moleculares , RNA Helicases/química , Serina Endopeptidases/química , Replicação Viral , Zika virus/enzimologia
6.
J Mol Cell Biol ; 11(1): 78-90, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30535232

RESUMO

Stimulatory regulators for DNA methyltransferase activity, such as Dnmt3L and some Dnmt3b isoforms, affect DNA methylation patterns, thereby maintaining gene body methylation and maternal methylation imprinting, as well as the methylation landscape of pluripotent cells. Here we show that metastasis-related methyltransferase 1 (Merm1), a protein deleted in individuals with Williams-Beuren syndrome, acts as a repressive regulator of Dnmt3a. Merm1 interacts with Dnmt3a and represses its methyltransferase activity with the requirement of the binding motif for S-adenosyl-L-methionine. Functional analysis of gene regulation revealed that Merm1 is capable of maintaining hypomethylated rRNA gene bodies and co-localizes with RNA polymerase I in the nucleolus. Dnmt3a recruits Merm1, and in return, Merm1 ensures the binding of Dnmt3a to hypomethylated gene bodies. Such interplay between Dnmt3a and Merm1 facilitates transcriptional elongation by RNA polymerase I. Our findings reveal a repressive factor for Dnmt3a and uncover a molecular mechanism underlying transcriptional elongation of rRNA genes.

8.
Elife ; 52016 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-26812545

RESUMO

Human cytomegalovirus (hCMV) immediate early 1 (IE1) protein associates with condensed chromatin of the host cell during mitosis. We have determined the structure of the chromatin-tethering domain (CTD) of IE1 bound to the nucleosome core particle, and discovered that IE1-CTD specifically interacts with the H2A-H2B acidic patch and impairs the compaction of higher-order chromatin structure. Our results suggest that IE1 loosens up the folding of host chromatin during hCMV infections.


Assuntos
Cromatina/metabolismo , Citomegalovirus/fisiologia , Interações Hospedeiro-Patógeno , Proteínas Imediatamente Precoces/química , Proteínas Imediatamente Precoces/metabolismo , Nucleossomos/metabolismo , Humanos , Ligação Proteica
9.
Genes Dev ; 29(10): 1058-73, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-25943375

RESUMO

Specific recognition of centromere-specific histone variant CENP-A-containing chromatin by CENP-N is an essential process in the assembly of the kinetochore complex at centromeres prior to mammalian cell division. However, the mechanisms of CENP-N recruitment to centromeres/kinetochores remain unknown. Here, we show that a CENP-A-specific RG loop (Arg80/Gly81) plays an essential and dual regulatory role in this process. The RG loop assists the formation of a compact "ladder-like" structure of CENP-A chromatin, concealing the loop and thus impairing its role in recruiting CENP-N. Upon G1/S-phase transition, however, centromeric chromatin switches from the compact to an open state, enabling the now exposed RG loop to recruit CENP-N prior to cell division. Our results provide the first insights into the mechanisms by which the recruitment of CENP-N is regulated by the structural transitions between compaction and relaxation of centromeric chromatin during the cell cycle.


Assuntos
Ciclo Celular/fisiologia , Centrômero/química , Centrômero/metabolismo , Cromatina/química , Proteínas Cromossômicas não Histona/metabolismo , Linhagem Celular , Proliferação de Células , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/química , Cromossomos/metabolismo , Células HeLa , Humanos , Cinetocoros/química , Cinetocoros/metabolismo , Ligação Proteica , Transporte Proteico , Fase S/fisiologia
10.
Dev Cell ; 32(1): 68-81, 2015 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-25556658

RESUMO

The H3 histone variant CENP-A is an epigenetic marker critical for the centromere identity and function. However, the precise regulation of the spatiotemporal deposition and propagation of CENP-A at centromeres during the cell cycle is still poorly understood. Here, we show that CENP-A is phosphorylated at Ser68 during early mitosis by Cdk1. Our results demonstrate that phosphorylation of Ser68 eliminates the binding of CENP-A to the assembly factor HJURP, thus preventing the premature loading of CENP-A to the centromere prior to mitotic exit. Because Cdk1 activity is at its minimum at the mitotic exit, the ratio of Cdk1/PP1α activity changes in favor of Ser68 dephosphorylation, thus making CENP-A available for centromeric deposition by HJURP. Thus, we reveal that dynamic phosphorylation of CENP-A Ser68 orchestrates the spatiotemporal assembly of newly synthesized CENP-A at active centromeres during the cell cycle.


Assuntos
Autoantígenos/metabolismo , Ciclo Celular/fisiologia , Centrômero/fisiologia , Proteínas Cromossômicas não Histona/metabolismo , Quinases Ciclina-Dependentes/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteína Fosfatase 1/metabolismo , Serina/metabolismo , Western Blotting , Proteína Quinase CDC2 , Proteína Centromérica A , Cromatina/genética , Imunofluorescência , Células HEK293 , Células HeLa , Humanos , Imunoprecipitação , Mitose/fisiologia , Nucleossomos , Fosforilação
11.
Genes Dev ; 25(9): 901-6, 2011 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-21478274

RESUMO

In higher eukaryotes, the centromere is epigenetically specified by the histone H3 variant Centromere Protein-A (CENP-A). Deposition of CENP-A to the centromere requires histone chaperone HJURP (Holliday junction recognition protein). The crystal structure of an HJURP-CENP-A-histone H4 complex shows that HJURP binds a CENP-A-H4 heterodimer. The C-terminal ß-sheet domain of HJURP caps the DNA-binding region of the histone heterodimer, preventing it from spontaneous association with DNA. Our analysis also revealed a novel site in CENP-A that distinguishes it from histone H3 in its ability to bind HJURP. These findings provide key information for specific recognition of CENP-A and mechanistic insights into the process of centromeric chromatin assembly.


Assuntos
Autoantígenos/química , Proteínas Cromossômicas não Histona/química , Proteínas de Ligação a DNA/química , Histonas/química , Modelos Moleculares , Autoantígenos/metabolismo , Proteína Centromérica A , Proteínas Cromossômicas não Histona/metabolismo , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Histonas/metabolismo , Humanos , Ligação Proteica , Estrutura Quaternária de Proteína
12.
Artigo em Inglês | MEDLINE | ID: mdl-20383014

RESUMO

Acyl-CoA dehydrogenase [acyl-CoA:(acceptor) 2,3-oxidoreductase; EC 1.3.99.3] catalyzes the first reaction step in mitochondrial fatty-acid beta-oxidation. Here, the very-long-chain acyl-CoA dehydrogenase from Caenorhabditis elegans (cVLCAD) has been cloned and overexpressed in Escherichia coli strain BL21 (DE3). Interestingly, unlike other very-long-chain acyl-CoA dehydrogenases, cVLCAD was found to form a tetramer by size-exclusion chromatography coupled with in-line static light-scattering, refractive-index and ultraviolet measurements. Purified cVLCAD (12 mg ml(-1)) was successfully crystallized by the hanging-drop vapour-diffusion method under conditions containing 100 mM Tris-HCl pH 8.0, 150 mM sodium chloride, 200 mM magnesium formate and 13% PEG 3350. The crystal has a tetragonal form and a complete diffraction data set was collected and processed to 1.8 A resolution. The crystal belonged to space group C2, with unit-cell parameters a = 138.6, b = 116.7, c = 115.3 A, alpha = gamma = 90.0, beta = 124.0 degrees . A self-rotation function indicated the existence of one noncrystallographic twofold axis. A preliminary molecular-replacement solution further confirmed the presence of two molecules in one asymmetric unit, which yields a Matthews coefficient V(M) of 2.76 A(3) Da(-1) and a solvent content of 55%.


Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/química , Caenorhabditis elegans/enzimologia , Acil-CoA Desidrogenase de Cadeia Longa/isolamento & purificação , Animais , Cristalização , Cristalografia por Raios X , Peso Molecular
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