Lipids of yeasts.

Rattray, J B; Schibeci, A; Kidby, D K

doi:10.1128/mmbr.39.3.197-231.1975

Cited by 191 publications

(66 citation statements)

References 203 publications

(330 reference statements)

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“…For all phospholipid species analysed in the positive-ion mode, the composition of acyl chains was determined by the neutral loss of these structures. In sum, PE and PC, followed by PS, were the most abundant phospholipids found in the MS analyses, consistent with the typical lipid distribution in pathogenic yeasts (Rattray et al, 1975).…”

Section: Membrane Phospholipids Are Present In Vesicular Lipid Extractssupporting

confidence: 83%

Vesicular transport inHistoplasma capsulatum: an effective mechanism for trans-cell wall transfer of proteins and lipids in ascomycetes

Albuquerque¹,

Nakayasu²,

Rodrigues³

et al. 2008

Cellular Microbiology

314

426

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SummaryVesicular secretion of macromolecules has recently been described in the basidiomycete Cryptococcus neoformans, raising the question as to whether ascomycetes similarly utilize vesicles for transport. In the present study, we examine whether the clinically important ascomycete Histoplasma capsulatum produce vesicles and utilized these structures to secrete macromolecules. Transmission electron microscopy (TEM) shows transcellular secretion of vesicles by yeast cells. Proteomic and lipidomic analyses of vesicles isolated from culture supernatants reveal a rich collection of macromolecules involved in diverse processes, including metabolism, cell recycling, signalling and virulence. The results demonstrate that H. capsulatum can utilize a transcell wall vesicular transport secretory mechanism to promote virulence. Additionally, TEM of supernatants collected from Candida albicans, Candida parapsilosis, Sporothrix schenckii and Saccharomyces cerevisiae documents that vesicles are similarly produced by additional ascomycetes. The vesicles from H. capsulatum react with immune serum from patients with histoplasmosis, providing an association of the vesicular products with pathogenesis. The findings support the proposal that vesicular secretion is a general mechanism in fungi for the transport of macromolecules related to virulence and that this process could be a target for novel therapeutics.

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Section: Membrane Phospholipids Are Present In Vesicular Lipid Extractssupporting

confidence: 83%

Vesicular transport inHistoplasma capsulatum: an effective mechanism for trans-cell wall transfer of proteins and lipids in ascomycetes

Albuquerque¹,

Nakayasu²,

Rodrigues³

et al. 2008

Cellular Microbiology

314

426

View full text Add to dashboard Cite

show abstract

“…5). Since 95% of all FA in yeast exist as fatty acyl chains of membrane lipids, total FA levels reflect yeast membrane content (46) and the 1a-induced increase in FA must represent an increase in membrane content. CAP expression increased total FA accumulation by 60% ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Bromovirus RNA Replication Compartment Formation Requires Concerted Action of 1a's Self-Interacting RNA Capping and Helicase Domains

Diaz

Gallei

Ahlquist

2012

J Virol

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All positive-strand RNA viruses replicate their genomes in association with rearranged intracellular membranes such as singleor double-membrane vesicles. Brome mosaic virus (BMV) RNA synthesis occurs in vesicular endoplasmic reticulum (ER) membrane invaginations, each induced by many copies of viral replication protein 1a, which has N-terminal RNA capping and C-terminal helicase domains. Although the capping domain is responsible for 1a membrane association and ER targeting, neither this domain nor the helicase domain was sufficient to induce replication vesicle formation. Moreover, despite their potential for mutual interaction, the capping and helicase domains showed no complementation when coexpressed in trans. Crosslinking showed that the capping and helicase domains each form trimers and larger multimers in vivo, and the capping domain formed extended, stacked, hexagonal lattices in vivo. Furthermore, coexpressing the capping domain blocked the ability of fulllength 1a to form replication vesicles and replicate RNA and recruited full-length 1a into mixed hexagonal lattices with the capping domain. Thus, BMV replication vesicle formation and RNA replication depend on the direct linkage and concerted action of 1a's self-interacting capping and helicase domains. In particular, the capping domain's strong dominant-negative effects showed that the ability of full-length 1a to form replication vesicles was highly sensitive to disruption by non-productively titrating lattice-forming self-interactions of the capping domain. These and other findings shed light on the roles and interactions of 1a domains in replication compartment formation and support prior results suggesting that 1a induces replication vesicles by forming a capsid-like interior shell. P ositive-strand RNA viruses are the largest genetic class of viruses and include many clinically important human pathogens as well as animal and plant pathogens. Postive-strand RNA virus genome replication and transcription occur in organelle-like structures that organize replication factors and templates and protect them from host defenses (11,35,38). These novel RNA replication compartments are induced by virus-specific membrane rearrangements such single-and double-membrane vesicles or appressed membranes or both (20,29,31,44,52,53).Brome mosaic virus (BMV), a member of the alphavirus-like superfamily of human, animal, and plant viruses, has been extensively studied as a model for positive-strand RNA virus RNA replication. BMV's genome is divided among three capped RNAs. RNA3 is dispensable for RNA replication but encodes cell-to-cell movement of protein 3a and the coat protein, both required for systemic spread of virus infection (6, 36). RNA1 and RNA2 encode RNA replication factors 1a and 2a pol , respectively. 1a is a multifunctional protein with key roles in the assembly and function of the viral RNA replication complexes. 1a contains an N-proximal RNA capping domain (2, 3, 30) and a C-terminal NTPase/RNA helicase-like domain (referred to here as the helicase ...

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“…The affected OLE1 gene encodes an integral ER membrane protein, ⌬9 fatty acid desaturase, essential for conversion of saturated fatty acids (SFAs) to unsaturated fatty acids (UFAs) (44,45). These UFAs are incorporated into membrane lipids and are major determinants of membrane fluidity and plasticity (10,36,40,42,47). We found that the OLE1 protein was not required for BMV RNA replication but that one or more steps between template recognition and initiation of viral RNA synthesis required UFAs at levels far above those required for yeast growth.…”

mentioning

confidence: 88%

Mutation of Host Δ9 Fatty Acid Desaturase Inhibits Brome Mosaic Virus RNA Replication between Template Recognition and RNA Synthesis

Lee

Ishikawa

Ahlquist

2001

J Virol

123

120

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All positive-strand RNA viruses assemble their RNA replication complexes on intracellular membranes. Brome mosaic virus (BMV) replicates its RNA in endoplasmic reticulum (ER)-associated complexes in plant cells and the yeast Saccharomyces cerevisiae. BMV encodes RNA replication factors 1a, with domains implicated in RNA capping and helicase functions, and 2a, with a central polymerase-like domain. Factor 1a interacts independently with the ER membrane, viral RNA templates, and factor 2a to form RNA replication complexes on the perinuclear ER. We show that BMV RNA replication is severely inhibited by a mutation in OLE1, an essential yeast chromosomal gene encoding ⌬9 fatty acid desaturase, an integral ER membrane protein and the first enzyme in unsaturated fatty acid synthesis. OLE1 deletion and medium supplementation show that BMV RNA replication requires unsaturated fatty acids, not the Ole1 protein, and that viral RNA replication is much more sensitive than yeast growth to reduced unsaturated fatty acid levels. In ole1 mutant yeast, 1a still becomes membrane associated, recruits 2a to the membrane, and recognizes and stabilizes viral RNA templates normally. However, RNA replication is blocked prior to initiation of negative-strand RNA synthesis. The results show that viral RNA synthesis is highly sensitive to lipid composition and suggest that proper membrane fluidity or plasticity is essential for an early step in RNA replication. The strong unsaturated fatty acid dependence also demonstrates that modulating fatty acid balance can be an effective antiviral strategy.All positive-strand RNA viruses of eukaryotes studied to date have RNA replication complexes localized to intracellular membranes, often in association with infection-specific membrane proliferation and or vesiculation (28,29,38,39,41). Multiple results indicate that membrane association is important for viral RNA synthesis. In vitro synthesis of positivestrand RNAs of picornaviruses and nodaviruses depends on membranes (31, 48). Activation of the alphavirus Semliki Forest virus (SFV) RNA-capping enzyme requires lipids with anionic head groups (3). Cerulenin, an inhibitor of lipid synthesis, inhibits RNA replication by poliovirus and SFV (16,34). Brefeldin A, an inhibitor of secretory vesicle formation, severely inhibits RNA replication by poliovirus and rhinovirus, though not by some other picornaviruses (11,20,30). Despite these results, the nature and function of membrane association in positive-strand RNA virus replication remain poorly understood.Brome mosaic virus (BMV) is a representative member of the alphavirus-like superfamily of human, animal, and plant positive-strand RNA viruses. The BMV genome is composed of three RNAs. RNA1 and RNA2 respectively encode 1a and 2a, the only BMV proteins required for RNA replication. 1a and 2a interact (25) and contain three domains conserved with those of other superfamily members. 1a contains an N-terminal domain with m 7 G methyltransferase and m 7 GMP covalent binding activities required for capping...

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Lipids of yeasts.

Cited by 191 publications

References 203 publications

Vesicular transport inHistoplasma capsulatum: an effective mechanism for trans-cell wall transfer of proteins and lipids in ascomycetes

Vesicular transport inHistoplasma capsulatum: an effective mechanism for trans-cell wall transfer of proteins and lipids in ascomycetes

Bromovirus RNA Replication Compartment Formation Requires Concerted Action of 1a's Self-Interacting RNA Capping and Helicase Domains

Mutation of Host Δ9 Fatty Acid Desaturase Inhibits Brome Mosaic Virus RNA Replication between Template Recognition and RNA Synthesis

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