707 research outputs found
A process independent of the anaphase-promoting complex contributes to instability of the yeast S phase cyclin Clb5
Proteolytic destruction of many cyclins is induced by a multi-subunit ubiquitin ligase termed the anaphase promoting complex/ cyclosome (APC/C). In the budding yeast Saccharomyces cerevisiae, the S phase cyclin Clb5 and the mitotic cyclins Clb1-4 are known as substrates of this complex. The relevance of APC/C in proteolysis of Clb5 is still under debate. Importantly, a deletion of the Clb5 destruction box has little influence on cell cycle progression. To understand Clb5 degradation in more detail, we applied in vivo pulse labeling to determine the half-life of Clb5 at different cell cycle stages and in the presence or absence of APC/C activity. Clb5 is significantly unstable, with a half-life of ∼8-10 min, at cell cycle periods when APC/C is inactive and in mutants impaired in APC/C function. A Clb5 version lacking its cyclin destruction box is similarly unstable. The half-life of Clb5 is further decreased in a destruction box-dependent manner to 3-5 min in mitotic or G 1 cells with active APC/C. Clb5 instability is highly dependent on the function of the proteasome. We conclude that Clb5 proteolysis involves two different modes for targeting of Clb5 to the proteasome, an APC/C-dependent and an APC/C-independent mechanism. These different modes apparently have overlapping functions in restricting Clb5 levels in a normal cell cycle, but APC/C function is essential in the presence of abnormally high Clb5 levels. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc
Draft Genome Sequence of the Phenazine-Producing \u3ci\u3ePseudomonas fluorescens\u3c/i\u3e Strain 2-79
Pseudomonas fluorescens strain 2-79, a natural isolate of the rhizosphere of wheat (Triticum aestivum L.), possesses antagonistic potential toward several fungal pathogens. We report the draft genome sequnce of strain 2-79, which comprises 5,674 protein-coding sequences
One Juliet and four Romeos: VeA and its methyltransferases
Fungal secondary metabolism has become an important research topic with great
biomedical and biotechnological value. In the postgenomic era, understanding the diversity
and the molecular control of secondary metabolites (SMs) are two challenging tasks
addressed by the research community. Discovery of the LaeA methyltransferase 10 years
ago opened up a new horizon on the control of SM research when it was found
that expression of many SM gene clusters is controlled by LaeA. While the molecular
function of LaeA remains an enigma, discovery of the velvet family proteins as interaction
partners further extended the role of the LaeA beyond secondary metabolism. The
heterotrimeric VelB–VeA–LaeA complex plays important roles in development, sporulation,
secondary metabolism, and pathogenicity. Recently, three other methyltransferases have
been found to associate with the velvet complex, the LaeA-like methyltransferase F and
the methyltransferase heterodimers VipC–VapB. Interaction of VeA with at least four
methyltransferase proteins indicates a molecular hub function for VeA that questions: Is
there a VeA supercomplex or is VeA part of a highly dynamic cellular control network with
many different partners
Heavy metal induced expression of PcaA provides cadmium tolerance to Aspergillus fumigatus and supports its virulence in the Galleria mellonella model
K
The Nma1 protein promotes long distance transport mediated by early endosomes in Ustilago maydis
Early endosomes (EEs) are part of the endocytic transport pathway and resemble the earliest class of transport vesicles between the internalization of extracellular material, their cellular distribution or vacuolar degradation. In filamentous fungi, EEs fulfill important functions in long distance transport of cargoes as mRNAs, ribosomes, and peroxisomes. Formation and maturation of early endosomes is controlled by the specific membrane-bound Rab-GTPase Rab5 and tethering complexes as CORVET (class C core vacuole/endosome tethering). In the basidiomycete Ustilago maydis, Rab5a is the prominent GTPase to recruit CORVET to EEs; in rab5a deletion strains, this function is maintained by the second EE-associated GTPase Rab5b. The tethering- and core-subunits of CORVET are essential, buttressing a central role for EE transport in U. maydis. The function of EEs in long distance transport is supported by the Nma1 protein that interacts with the Vps3 subunit of CORVET. The interaction stabilizes the binding of Vps3 to the CORVET core complex that is recruited to Rab5a via Vps8. Deletion of nma1 leads to a significantly reduced number of EEs, and an increased conversion rate of EEs to late endosomes. Thus, Nma1 modulates the lifespan of EEs to ensure their availability for the various long distance transport processes
Antimicrobial propensity of ultrananocrystalline diamond films with embedded silver nanodroplets
RNAseq analysis of Aspergillus fumigatus in blood reveals a just wait and see resting stage behavior
Background:
Invasive aspergillosis is started after germination of Aspergillus fumigatus conidia that are inhaled by susceptible individuals. Fungal hyphae can grow in the lung through the epithelial tissue and disseminate hematogenously to invade into other organs. Low fungaemia indicates that fungal elements do not reside in the bloodstream for long.
Results:
We analyzed whether blood represents a hostile environment to which the physiology of A. fumigatus has to adapt. An in vitro model of A. fumigatus infection was established by incubating mycelium in blood. Our model allowed to discern the changes of the gene expression profile of A. fumigatus at various stages of the infection. The majority of described virulence factors that are connected to pulmonary infections appeared not to be activated during the blood phase. Three active processes were identified that presumably help the fungus to survive the blood environment in an advanced phase of the infection: iron homeostasis, secondary metabolism, and the formation of detoxifying enzymes.
Conclusions:
We propose that A. fumigatus is hardly able to propagate in blood. After an early stage of sensing the environment, virtually all uptake mechanisms and energy-consuming metabolic pathways are shut-down. The fungus appears to adapt by trans-differentiation into a resting mycelial stage. This might reflect the harsh conditions in blood where A. fumigatus cannot take up sufficient nutrients to establish self-defense mechanisms combined with significant growth
Membrane-Bound Methyltransferase Complex VapA-VipC-VapB Guides Epigenetic Control of Fungal Development
Epigenetic and transcriptional control of gene
expression must be coordinated in response to
external signals to promote alternative multicellular
developmental programs. The membrane-associated
trimeric complex VapA-VipC-VapB controls a
signal transduction pathway for fungal differentiation.
The VipC-VapB methyltransferases are tethered
to the membrane by the FYVE-like zinc finger protein
VapA, allowing the nuclear VelB-VeA-LaeA complex
to activate transcription for sexual development.
Once the release from VapA is triggered, VipCVapB
is transported into the nucleus. VipC-VapB
physically interacts with VeA and reduces its nuclear
import and protein stability, thereby reducing the
nuclear VelB-VeA-LaeA complex. Nuclear VapB
methyltransferase diminishes the establishment of
facultative heterochromatin by decreasing histone 3
lysine 9 trimethylation (H3K9me3). This favors activation
of the regulatory genes brlA and abaA, which
promote the asexual program. The VapA-VipCVapB
methyltransferase pathway combines control
of nuclear import and stability of transcription factors
with histone modification to foster appropriate differentiation
responses
A seed-like proteome in oil-rich tubers
There are numerous examples of plant organs or developmental stages that are desiccation-tolerant and can withstand extended periods of severe water loss. One prime example are seeds and pollen of many spermatophytes. However, in some plants, also vegetative organs can be desiccation-tolerant. One example are the tubers of yellow nutsedge (Cyperus esculentus), which also store large amounts of lipids similar to seeds. Interestingly, the closest known relative, purple nutsedge (Cyperus rotundus), generates tubers that do not accumulate oil and are not desiccation-tolerant. We generated nanoLC-MS/MS-based proteomes of yellow nutsedge in five replicates of four stages of tuber development and compared them to the proteomes of roots and leaves, yielding 2257 distinct protein groups. Our data reveal a striking upregulation of hallmark proteins of seeds in the tubers. A deeper comparison to the tuber proteome of the close relative purple nutsedge (C. rotundus) and a previously published proteome of Arabidopsis seeds and seedlings indicates that indeed a seed-like proteome was found in yellow but not purple nutsedge. This was further supported by an analysis of the proteome of a lipid droplet-enriched fraction of yellow nutsedge, which also displayed seed-like characteristics. One reason for the differences between the two nutsedge species might be the expression of certain transcription factors homologous to ABSCISIC ACID INSENSITIVE3, WRINKLED1, and LEAFY COTYLEDON1 that drive gene expression in Arabidopsis seed embryos
Current challenges of research on filamentous fungi in relation to human welfare and a sustainable bio-economy: a white paper.
The EUROFUNG network is a virtual centre of multidisciplinary expertise in the field of fungal biotechnology. The first academic-industry Think Tank was hosted by EUROFUNG to summarise the state of the art and future challenges in fungal biology and biotechnology in the coming decade. Currently, fungal cell factories are important for bulk manufacturing of organic acids, proteins, enzymes, secondary metabolites and active pharmaceutical ingredients in white and red biotechnology. In contrast, fungal pathogens of humans kill more people than malaria or tuberculosis. Fungi are significantly impacting on global food security, damaging global crop production, causing disease in domesticated animals, and spoiling an estimated 10 % of harvested crops. A number of challenges now need to be addressed to improve our strategies to control fungal pathogenicity and to optimise the use of fungi as sources for novel compounds and as cell factories for large scale manufacture of bio-based products. This white paper reports on the discussions of the Think Tank meeting and the suggestions made for moving fungal bio(techno)logy forward
- …