Arsenic (As) contamination in a paddy environment can cause phytotoxicity and elevated As accumulation in rice (Oryza sativa). The mechanism of As detoxification in rice is still poorly understood.
...We isolated an arsenate (As(V))-sensitive mutant of rice. Genomic resequencing and complementation identified OsCLT1, encoding a CRT-like transporter, as the causal gene for the mutant phenotype.
OsCLT1 is localized to the envelope membrane of plastids. The glutathione and γ-glutamylcysteine contents in roots of Osclt1 and RNA interference lines were decreased markedly compared with the wild-type (WT). The concentrations of phytochelatin PC2 in Osclt1 roots were only 32% and 12% of that in WT after As(V) and As(III) treatments, respectively. OsCLT1 mutation resulted in lower As accumulation in roots but higher As accumulation in shoots when exposed to As(V). Under As(III) treatment, Osclt1 accumulated a lower As concentration in roots but similar As concentration in shoots to WT. Further analysis showed that the reduction of As(V) to As(III) was decreased in Osclt1. Osclt1 was also hypersensitive to cadmium (Cd).
These results indicate that OsCLT1 plays an important role in glutathione homeostasis, probably by mediating the export of γ-glutamylcysteine and glutathione from plastids to the cytoplasm, which in turn affects As and Cd detoxification in rice.
Neurodegenerative diseases (NDs) are incurable and can develop progressively debilitating disorders, including dementia and ataxias. Alzheimer's disease and Parkinson's disease are the most common ...NDs that mainly affect the elderly people. There is an urgent need to develop new diagnostic tools so that patients can be accurately stratified at an early stage. As a common post‐translational modification, protein glycosylation plays a key role in physiological and pathological processes. The abnormal changes in glycosylation are associated with the altered biological pathways in NDs. The pathogenesis‐related proteins, like amyloid‐β and microtubule‐associated protein tau, have altered glycosylation. Importantly, specific glycosylation changes in cerebrospinal fluid, blood and urine are valuable for revealing neurodegeneration in the early stages. This review describes the emerging biomarkers based on glycoproteomics in NDs, highlighting the potential applications of glycoprotein biomarkers in the early detection of diseases, monitoring of the disease progression, and measurement of the therapeutic responses. The mass spectrometry‐based strategies for characterizing glycoprotein biomarkers are also introduced.
Neurodegenerative disease (ND) may lead to aberrant changes in glycoenzymes, including glycosyltransferases and glycosidases, which further regulate the key ND‐related molecules, such as amyloid precursor protein, nicastrin, β‐site APP‐cleaving enzyme 1β‐site APP‐cleaving enzyme 1, a disintegrin and metallopeptidase domain 10 (ADAM10), neprilysin, etc.
Efficient biosynthesis of microbial bioactive natural products (NPs) is beneficial for the survival of producers, while self‐protection is necessary to avoid self‐harm resulting from ...over‐accumulation of NPs. The underlying mechanisms for the effective but tolerable production of bioactive NPs are not well understood. Herein, in the biosynthesis of two fungal polyketide mycotoxins aurovertin E (1) and asteltoxin, we show that the cyclases in the gene clusters promote the release of the polyketide backbone, and reveal that a signal peptide is crucial for their subcellular localization and full activity. Meanwhile, the fungus adopts enzymatic acetylation as the major detoxification pathway of 1. If intermediates are over‐produced, the non‐enzymatic shunt pathways work as salvage pathways to avoid excessive accumulation of the toxic metabolites for self‐protection. These findings provided new insight into the interplay of efficient backbone release and multiple detoxification strategies for the production of fungal bioactive NPs.
The biosynthesis of aurovertins involves a coordinated strategy for the tolerable production of fungal mycotoxins. A cyclase promotes the release of the polyketide backbone, while enzymatic acetylation functions as the major detoxification pathway, and non‐enzymatic shunt pathways function as salvage routes to avoid excessive accumulation of the toxic metabolites.
The small‐molecule biosynthetic potential of most filamentous fungi has remained largely unexplored and represents an attractive source for the discovery of new compounds. Genome sequencing of ...Calcarisporium arbuscula, a mushroom‐endophytic fungus, revealed 68 core genes that are involved in natural product biosynthesis. This is in sharp contrast to the predominant production of the ATPase inhibitors aurovertin B and D in the wild‐type fungus. Inactivation of a histone H3 deacetylase led to pleiotropic activation and overexpression of more than 75 % of the biosynthetic genes. Sampling of the overproduced compounds led to the isolation of ten compounds of which four contained new structures, including the cyclic peptides arbumycin and arbumelin, the diterpenoid arbuscullic acid A, and the meroterpenoid arbuscullic acid B. Such epigenetic modifications therefore provide a rapid and global approach to mine the chemical diversity of endophytic fungi.
The endophytic fungus Calcarisporium arbuscula is rich in cryptic gene clusters for natural product biosynthesis. Removal of a global epigenetic repressor HdaA, the histone H3 deacetylase, activates the expression of over 75 % of the silenced gene clusters and enables the isolation of new natural products.
Streptomyces chattanoogensis L10 is the industrial producer of natamycin and has been proved a highly efficient host for diverse natural products. It has an enormous potential to be developed as a ...versatile cell factory for production of heterologous secondary metabolites. Here we developed a genome-reduced industrial Streptomyces chassis by rational 'design-build-test' pipeline.
To identify candidate large non-essential genomic regions accurately and design large deletion rationally, we performed genome analyses of S. chattanoogensis L10 by multiple computational approaches, optimized Cre/loxP recombination system for high-efficient large deletion and constructed a series of universal suicide plasmids for rapid loxP or loxP mutant sites inserting into genome. Subsequently, two genome-streamlined mutants, designated S. chattanoogensis L320 and L321, were rationally constructed by depletion of 1.3 Mb and 0.7 Mb non-essential genomic regions, respectively. Furthermore, several biological performances like growth cycle, secondary metabolite profile, hyphae morphological engineering, intracellular energy (ATP) and reducing power (NADPH/NADP
) levels, transformation efficiency, genetic stability, productivity of heterologous proteins and secondary metabolite were systematically evaluated. Finally, our results revealed that L321 could serve as an efficient chassis for the production of polyketides.
Here we developed the combined strategy of multiple computational approaches and site-specific recombination system to rationally construct genome-reduced Streptomyces hosts with high efficiency. Moreover, a genome-reduced industrial Streptomyces chassis S. chattanoogensis L321 was rationally constructed by the strategy, and the chassis exhibited several emergent and excellent performances for heterologous expression of secondary metabolite. The strategy could be widely applied in other Streptomyces to generate miscellaneous and versatile chassis with minimized genome. These chassis can not only serve as cell factories for high-efficient production of valuable polyketides, but also will provide great support for the upgrade of microbial pharmaceutical industry and drug discovery.
Azoxy bond is an important chemical bond and plays a crucial role in high energy density materials. However, the biosynthetic mechanism of azoxy bond remains enigmatic. Here we report that the azoxy ...bond biosynthesis of azoxymycins is an enzymatic and non-enzymatic coupling cascade reaction. In the first step, nonheme diiron N-oxygenase AzoC catalyzes the oxidization of amine to its nitroso analogue. Redox coenzyme pairs then facilitate the mutual conversion between nitroso group and hydroxylamine via the radical transient intermediates, which efficiently dimerize to azoxy bond. The deficiency of nucleophilic reactivity in AzoC is proposed to account for the enzyme's non-canonical oxidization of amine to nitroso product. Free nitrogen radicals induced by coenzyme pairs are proposed to be responsible for the efficient non-enzymatic azoxy bond formation. This mechanism study will provide molecular basis for the biosynthesis of azoxy high energy density materials and other valuable azoxy chemicals.
Streptomyces
is famous for its capability to produce the most abundant antibiotics in all kingdoms. All
Streptomyces
antibiotics are natural products, whose biosynthesis from the so-called gene ...clusters are elaborately regulated by pyramidal transcriptional regulatory cascades. In the past decades, scientists have striven to unveil the regulatory mechanisms involved in antibiotic production in
Streptomyces
. Here we mainly focus on three aspects of the regulation on antibiotic production. 1. The onset of antibiotic production triggered by hormones and their coupled receptors as regulators; 2. The cascades of global and pathway-specific regulators governing antibiotic production; 3. The feedback regulation of antibiotics and/or intermediates on the gene cluster expression for their coordinated production. This review will summarize how the antibiotic production is stringently regulated in
Streptomyces
based on the signaling
,
and lay a theoretical foundation for improvement of antibiotic production and potentially drug discovery.
The transition metal-free sulfenylation of CH bond for CS formation has been rapidly advanced and has become an eco-friendly synthetic tool for pharmacists and organic chemists. This review will ...focus on the recent five-year advances in CS bond formation via direct sulfenylation of C(sp3)H bonds under metal-free conditions and elaborate their mechanisms.
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In recent years, the transition metal-free sulfenylation of CH bond for CS formation has been rapidly advanced and has become an eco-friendly synthetic tool for pharmacists and organic chemists. Various natural or bioactive molecules such as (hetero)arenes, olefins, carbonyl compounds, alkanes, have been employed for sulfenylating reactions. This review will focus on the recent five-year advances in CS bond formation via direct sulfenylation of C(sp3)H bonds under metal-free conditions and elaborate their mechanisms from a new perspective.
NOTCH2NLC GGC repeat expansions were recently identified in neuronal intranuclear inclusion disease (NIID); however, it remains unclear whether they occur in other neurodegenerative disorders. This ...study aimed to investigate the role of intermediate‐length NOTCH2NLC GGC repeat expansions in Parkinson disease (PD). We screened for GGC repeat expansions in a cohort of 1,011 PD patients and identified 11 patients with intermediate‐length repeat expansions ranging from 41 to 52 repeats, with no repeat expansions in 1,134 controls. Skin biopsy revealed phospho‐alpha‐synuclein deposition, confirming the PD diagnosis in 2 patients harboring intermediate‐length repeat expansions instead of NIID or essential tremor. Fibroblasts from PD patients harboring intermediate‐length repeat expansions revealed NOTCH2NLC upregulation and autophagic dysfunction. Our results suggest that intermediate‐length repeat expansions in NOTCH2NLC are potentially associated with PD. ANN NEUROL 2021;89:182–187
Secondary metabolites as natural products from endophytic fungi are important sources of pharmaceuticals. However, there is currently little understanding of endophytic fungi at the omics levels ...about their potential in secondary metabolites. Calcarisporium arbuscula, an endophytic fungus from the fruit bodies of Russulaceae, produces a variety of secondary metabolites with anti-cancer, anti-nematode and antibiotic activities. A comprehensive survey of the genome and transcriptome of this endophytic fungus will help to understand its capacity to biosynthesize secondary metabolites and will lay the foundation for the development of this precious resource.
In this study, we reported the high-quality genome sequence of C. arbuscula NRRL 3705 based on Single Molecule Real-Time sequencing technology. The genome of this fungus is over 45 Mb in size, larger than other typical filamentous fungi, and comprises 10,001 predicted genes, encoding at least 762 secretory-proteins, 386 carbohydrate-active enzymes and 177 P450 enzymes. 398 virulence factors and 228 genes related to pathogen-host interactions were also predicted in this fungus. Moreover, 65 secondary metabolite biosynthetic gene clusters were revealed, including the gene cluster for the mycotoxin aurovertins. In addition, several gene clusters were predicted to produce mycotoxins, including aflatoxin, alternariol, destruxin, citrinin and isoflavipucine. Notably, two independent gene clusters were shown that are potentially involved in the biosynthesis of alternariol. Furthermore, RNA-Seq assays showed that only expression of the aurovertin gene cluster is much stronger than expression of the housekeeping genes under laboratory conditions, consistent with the observation that aurovertins are the predominant metabolites. Gene expression of the remaining 64 gene clusters for compound backbone biosynthesis was all lower than expression of the housekeeping genes, which partially explained poor production of other secondary metabolites in this fungus.
Our omics data, along with bioinformatics analysis, indicated that C. arbuscula NRRL 3705 contains a large number of biosynthetic gene clusters and has a huge potential to produce a profound number of secondary metabolites. This work also provides the basis for development of endophytic fungi as a new resource of natural products with promising biological activities.
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