scholarly journals Spliceosomal Prp8 intein at the crossroads of protein and RNA splicing

2018 ◽  
Author(s):  
Cathleen M. Green ◽  
Zhong Li ◽  
Olga Novikova ◽  
Valjean R. Bacot-Davis ◽  
Fenghan Gao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rna Splicing ◽  
Fungal Pathogen ◽  
Rna Catalysis ◽  
Protein Splicing ◽  
Reporter Assay ◽  
Structural Homology ◽  
Biologically Relevant ◽  
Human Fungal Pathogen ◽  
Self Splicing

The spliceosome is a large ribonucleoprotein complex that removes introns from pre-mRNAs. At its functional core lies the essential Prp8 protein. Across diverse eukaryotes, this protein cofactor of RNA catalysis harbors a self-splicing element, called an intein. Inteins in Prp8 are extremely pervasive and are found at seven different sites in various species. Here, we focus on the Prp8 intein from Cryptococcus neoformans, a human fungal pathogen. We solved the crystal structure of this intein, revealing structural homology among self-splicing sequences in eukaryotes, including Hedgehog protein. Working with the C. neoformans Prp8 intein in a reporter assay, we find that the biologically relevant divalent metals copper and zinc inhibit intein splicing, albeit by two different mechanisms. Copper likely stimulates reversible modifications on a catalytically important cysteine, whereas zinc binds via the same critical cysteine with a Kd of ~1 nM. An intein-containing Prp8 precursor model is presented, suggesting that metal-induced protein splicing inhibition would disturb function of both Prp8 and the spliceosome. These results indicate that Prp8 protein splicing can be modulated, and that this could alter spliceosome function and RNA splicing under specific conditions.

Mithochondrial biogenesis: recent developments and insights

1988 ◽  
Vol 319 (1193) ◽  
pp. 85-95
Keyword(s):  
Rna Splicing ◽  
Mitochondrial Genes ◽  
Pivotal Role ◽  
Mitochondrial Proteins ◽  
Rna Catalysis ◽  
Expression Of Genes ◽  
Recent Developments ◽  
Self Splicing ◽  
Shed Light

Biosynthesis of a functional mitochondrion requires the coordinate expression of genes in both mitochondrial and nuclear DNAs. In yeast, three mitochondrial genes are split and RNA splicing plays a pivotal role in their expression. The recent finding that some introns are capable of self-splicing activity in vitro has permitted analysis of the mechanisms involved in RNA catalysis and may eventually shed light on the evolution of splicing mechanisms in general. Most mitochondrial proteins are encoded by nuclear genes, synthesized in the cytoplasm and imported by the organelle. The availability of cloned genes coding for several constituent subunits of the ubiquinol-cytochrome c reductase, which are imported by mitochondria, has allowed study of selected steps in the addressing of proteins to mitochondria and their intercompartmental sorting within the organelle. Recent developments are discussed.

scholarly journals pH-Dependant Antifungal Activity of Valproic Acid against the Human Fungal Pathogen Candida albicans

2017 ◽  
Vol 8 ◽  
Author(s):  
Julien Chaillot ◽  
Faiza Tebbji ◽  
Carlos García ◽  
Hugo Wurtele ◽  
René Pelletier ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Candida Albicans ◽  
Antifungal Activity ◽  
Fungal Pathogen ◽  
Human Fungal Pathogen

scholarly journals RNA splicing in Chlamydomonas chloroplasts. Self-splicing of 23 S preRNA

1991 ◽  
Vol 266 (6) ◽  
pp. 4023
Author(s):  
David L. Herrin ◽  
Yu-Fen Chen ◽  
Ciregory W. Schmidt
Keyword(s):  
Rna Splicing ◽  
Self Splicing

scholarly journals Pmt-Mediated O Mannosylation Stabilizes an Essential Component of the Secretory Apparatus, Sec20p, in Candida albicans

2004 ◽  
Vol 3 (5) ◽  
pp. 1164-1168 ◽  
Author(s):  
Yvonne Weber ◽  
Stephan K.-H. Prill ◽  
Joachim F. Ernst
Keyword(s):  
Endoplasmic Reticulum ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Wild Type ◽  
Rapid Degradation ◽  
Vesicle Traffic ◽  
Human Fungal Pathogen ◽  
Low Levels ◽  
Lumenal Domain ◽  
Secretory Apparatus

ABSTRACT Sec20p is an essential endoplasmic reticulum (ER) membrane protein in yeasts, functioning as a tSNARE component in retrograde vesicle traffic. We show that Sec20p in the human fungal pathogen Candida albicans is extensively O mannosylated by protein mannosyltransferases (Pmt proteins). Surprisingly, Sec20p occurs at wild-type levels in a pmt6 mutant but at very low levels in pmt1 and pmt4 mutants and also after replacement of specific Ser/Thr residues in the lumenal domain of Sec20p. Pulse-chase experiments revealed rapid degradation of unmodified Sec20p (38.6 kDa) following its biosynthesis, while the stable O-glycosylated form (50 kDa) was not formed in a pmt1 mutant. These results suggest a novel function of O mannosylation in eukaryotes, in that modification by specific Pmt proteins will prevent degradation of ER-resident membrane proteins via ER-associated degradation or a proteasome-independent pathway.

An enzyme captured in two conformational states: crystal structure ofS-adenosyl-L-homocysteine hydrolase fromBradyrhizobium elkanii

2015 ◽  
Vol 71 (12) ◽  
pp. 2422-2432 ◽  
Author(s):  
Tomasz Manszewski ◽  
Kriti Singh ◽  
Barbara Imiolczyk ◽  
Mariusz Jaskolski
Keyword(s):  
Crystal Structure ◽  
Enzymatic Reaction ◽  
Binding Domain ◽  
Dimerization Domain ◽  
Biologically Relevant ◽  
Cofactor Binding ◽  
Enzymatic Regulation ◽  
Ligand Free ◽  
Substrate Binding Domain ◽  
Methyl Group Transfer

S-Adenosyl-L-homocysteine hydrolase (SAHase) is involved in the enzymatic regulation ofS-adenosyl-L-methionine (SAM)-dependent methylation reactions. After methyl-group transfer from SAM,S-adenosyl-L-homocysteine (SAH) is formed as a byproduct, which in turn is hydrolyzed to adenosine (Ado) and homocysteine (Hcy) by SAHase. The crystal structure of BeSAHase, an SAHase fromBradyrhizobium elkanii, which is a nitrogen-fixing bacterial symbiont of legume plants, was determined at 1.7 Å resolution, showing the domain organization (substrate-binding domain, NAD+cofactor-binding domain and dimerization domain) of the subunits. The protein crystallized in its biologically relevant tetrameric form, with three subunits in a closed conformation enforced by complex formation with the Ado product of the enzymatic reaction. The fourth subunit is ligand-free and has an open conformation. The BeSAHase structure therefore provides a unique snapshot of the domain movement of the enzyme induced by the binding of its natural ligands.

scholarly journals The 5’ untranslated region of theEFG1transcript promotes its translation to regulate hyphal morphogenesis inCandida albicans

2018 ◽  
Author(s):  
Prashant R. Desai ◽  
Klaus Lengeler ◽  
Mario Kapitan ◽  
Silas Matthias Janßen ◽  
Paula Alepuz ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Regulatory Mechanisms ◽  
Untranslated Regions ◽  
Regulatory Sequence ◽  
Transcriptional Level ◽  
Human Fungal Pathogen ◽  
Hyphal Morphogenesis ◽  
Cellular Morphogenesis ◽  
Incandida Albicans

ABSTRACTExtensive 5’ untranslated regions (UTR) are a hallmark of transcripts determining hyphal morphogenesis inCandida albicans.The major transcripts of theEFG1gene, which are responsible for cellular morphogenesis and metabolism, contain a 5’ UTR of up to 1170 nt. Deletion analyses of the 5’ UTR revealed a 218 nt sequence that is required for production of the Efg1 protein and its functions in filamentation, without lowering the level and integrity of theEFG1transcript. Polysomal analyses revealed that the 218 nt 5’ UTR sequence is required for efficient translation of the Efg1 protein. Replacement of theEFG1ORF by the heterologous reporter geneCaCBGlucconfirmed the positive regulatory importance of the identified 5’ UTR sequence. In contrast to other reported transcripts containing extensive 5’ UTR sequences, these results indicate the positive translational function of the 5’ UTR sequence in theEFG1transcript, which is observed in context of the nativeEFG1promoter. The results suggest that the 5’ UTR recruits regulatory factors, possibly during emergence of the native transcript, which aid in translation of theEFG1transcript.IMPORTANCEMany of the virulence traits that makeCandida albicansan important human fungal pathogen are regulated on a transcriptional level. Here we report an important regulatory contribution of translation, which is exerted by the extensive 5’ untranslated regulatory sequence (5’ UTR) of the transcript for the protein Efg1, which determines growth, metabolism and filamentation in the fungus. Presence of the 5’ UTR is required for efficient translation of Efg1, to promote filamentation. Because transcripts for many relevant regulators contain extensive 5’ UTR sequences, it appears that virulence ofC. albicansdepends on the combination of transcriptional and translation regulatory mechanisms.

scholarly journals Epigenetic dynamics of centromeres and neocentromeres in Cryptococcus deuterogattii

PLoS Genetics ◽  
2021 ◽  
Vol 17 (8) ◽  
pp. e1009743
Author(s):  
Klaas Schotanus ◽  
Vikas Yadav ◽  
Joseph Heitman
Keyword(s):  
Dna Methylation ◽  
Transposable Element ◽  
Fungal Pathogen ◽  
Fusion Partner ◽  
Epigenetic Memory ◽  
Chromosome Fusion ◽  
Human Fungal Pathogen ◽  
Chromosome Fusions ◽  
The Impact ◽  
Active Centromere

Deletion of native centromeres in the human fungal pathogen Cryptococcus deuterogattii leads to neocentromere formation. Native centromeres span truncated transposable elements, while neocentromeres do not and instead span actively expressed genes. To explore the epigenetic organization of neocentromeres, we analyzed the distribution of the heterochromatic histone modification H3K9me2, 5mC DNA methylation and the euchromatin mark H3K4me2. Native centromeres are enriched for both H3K9me2 and 5mC DNA methylation marks and are devoid of H3K4me2, while neocentromeres do not exhibit any of these features. Neocentromeres in cen10Δ mutants are unstable and chromosome-chromosome fusions occur. After chromosome fusion, the neocentromere is inactivated and the native centromere of the chromosome fusion partner remains as the sole, active centromere. In the present study, the active centromere of a fused chromosome was deleted to investigate if epigenetic memory promoted the re-activation of the inactive neocentromere. Our results show that the inactive neocentromere is not re-activated and instead a novel neocentromere forms directly adjacent to the deleted centromere of the fused chromosome. To study the impact of transcription on centromere stability, the actively expressed URA5 gene was introduced into the CENP-A bound regions of a native centromere. The introduction of the URA5 gene led to a loss of CENP-A from the native centromere, and a neocentromere formed adjacent to the native centromere location. Remarkably, the inactive, native centromere remained enriched for heterochromatin, yet the integrated gene was expressed and devoid of H3K9me2. A cumulative analysis of multiple CENP-A distribution profiles revealed centromere drift in C. deuterogattii, a previously unreported phenomenon in fungi. The CENP-A-binding shifted within the ORF-free regions and showed a possible association with a truncated transposable element. Taken together, our findings reveal that neocentromeres in C. deuterogattii are highly unstable and are not marked with an epigenetic memory, distinguishing them from native centromeres.

scholarly journals mSphere of Influence: the Power of Yeast Genetics Still Going Strong!

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Felipe H. Santiago-Tirado
Keyword(s):  
Genetic Analysis ◽  
Fungal Pathogen ◽  
Cell Biology ◽  
Genetic Manipulation ◽  
Chemical Genetics ◽  
Yeast Genetics ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Link Type ◽  
Fungal Meningitis

ABSTRACT Felipe Santiago-Tirado studies the cell biology of cryptococcal infections. In this mSphere of Influence article, he reflects on how the papers “Systematic Genetic Analysis of Virulence in the Human Fungal Pathogen Cryptococcus neoformans” (https://doi.org/10.1016/j.cell.2008.07.046) and “Unraveling the Biology of a Fungal Meningitis Pathogen Using Chemical Genetics” (https://doi.org/10.1016/j.cell.2014.10.044) by the Noble and Madhani groups influenced his thinking by showcasing the various modern applications of yeast genetics in an organism where genetic manipulation was difficult.

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