ORCID Profile
0000-0002-0508-0084
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Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.CHOM.2022.04.015
Abstract: Argonaute (Ago) proteins are widespread nucleic-acid-guided enzymes that recognize targets through complementary base pairing. Although, in eukaryotes, Agos are involved in RNA silencing, the functions of prokaryotic Agos (pAgos) remain largely unknown. In particular, a clade of truncated and catalytically inactive pAgos (short pAgos) lacks characterization. Here, we reveal that a short pAgo protein in the archaeon Sulfolobus islandicus, together with its two genetically associated proteins, Aga1 and Aga2, provide robust antiviral protection via abortive infection. Aga2 is a toxic transmembrane effector that binds anionic phospholipids via a basic pocket, resulting in membrane depolarization and cell killing. Ago and Aga1 form a stable complex that exhibits nucleic-acid-directed nucleic-acid-recognition ability and directly interacts with Aga2, pointing to an immune sensing mechanism. Together, our results highlight the cooperation between pAgos and their widespread associated proteins, suggesting an uncharted ersity of pAgo-derived immune systems.
Publisher: Springer Science and Business Media LLC
Date: 09-2016
DOI: 10.1038/NATURE19366
Abstract: Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the s ling and cultivation of viruses, genome-level viral ersity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface- and deep-ocean viruses s led during the Tara Oceans and Malaspina research expeditions, and analyse the resulting 'global ocean virome' dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete s ling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome s le. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where they act as key players in nutrient cycling and trophic networks.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 17-09-2021
Abstract: Cells produce specialized machinery to produce functional β-barrel proteins that are involved in cross-membrane transport and membrane protein biogenesis in eukaryotic organelles and some bacteria. Wang et al . studied one of these systems that is itself a β-barrel, the mitochondrial sorting and assembly machinery (SAM), in complex with one of its client proteins, translocase of the outer membrane (TOM). TOM subunits can be added one at a time while the protein is bound to SAM. Compared with the full TOM core complex, the final TOM core subunit clashes with SAM and suggests that release of TOM may be driven by its association. —MAF
Publisher: Wiley
Date: 03-01-2021
DOI: 10.1111/NPH.17128
Publisher: Elsevier BV
Date: 12-2022
Publisher: Springer Science and Business Media LLC
Date: 18-08-2022
DOI: 10.1038/S41564-022-01197-7
Abstract: First discovered in the 1980s, retrons are bacterial genetic elements consisting of a reverse transcriptase and a non-coding RNA (ncRNA). Retrons mediate antiphage defence in bacteria but their structure and defence mechanisms are unknown. Here, we investigate the Escherichia coli Ec86 retron and use cryo-electron microscopy to determine the structures of the Ec86 (3.1 Å) and cognate effector-bound Ec86 (2.5 Å) complexes. The Ec86 reverse transcriptase exhibits a characteristic right-hand-like fold consisting of finger, palm and thumb subdomains. Ec86 reverse transcriptase reverse-transcribes part of the ncRNA into satellite, multicopy single-stranded DNA (msDNA, a DNA-RNA hybrid) that we show wraps around the reverse transcriptase electropositive surface. In msDNA, both inverted repeats are present and the 3' sides of the DNA/RNA chains are close to the reverse transcriptase active site. The Ec86 effector adopts a two-lobe fold and directly binds reverse transcriptase and msDNA. These findings offer insights into the structure-function relationship of the retron-effector unit and provide a structural basis for the optimization of retron-based genome editing systems.
Publisher: Springer Science and Business Media LLC
Date: 25-06-2014
Publisher: Wiley
Date: 05-05-2021
DOI: 10.1111/MPP.13064
Abstract: Zymoseptoria tritici , the causal agent of Septoria tritici blotch, is a fungal wheat pathogen that causes significant global yield losses. Within Z. tritici populations, quantitative differences in virulence among different isolates are commonly observed however, the genetic components that underpin these differences remain elusive. In this study, intraspecific comparative transcriptomic analysis was used to identify candidate genes that contribute to differences in virulence on the wheat cultivar WW2449. This led to the identification of a multicopy gene that was not expressed in the high‐virulence isolate when compared to the medium‐ and low‐virulence isolates. Further investigation suggested this gene resides in a 7.9‐kb transposon. Subsequent long‐read sequencing of the isolates used in the transcriptomic analysis confirmed that this gene did reside in an active Class II transposon, which is composed of four genes named REP9‐1 to ‐4 . Silencing and overexpression of REP9‐1 in two distinct genetic backgrounds demonstrated that its expression alone reduces the number of pycnidia produced by Z. tritici during infection. The REP9‐1 gene identified within a Class II transposon is the first discovery of a gene in a transposable element that influences the virulence of Z. tritici . This discovery adds further complexity to genetic loci that contribute to quantitative virulence in this important pathogen.
Publisher: Frontiers Media SA
Date: 25-03-2020
No related grants have been discovered for Chen Wang.