Identification of the guanine nucleotide exchange factor for SAR1 in the filamentous fungal model Aspergillus nidulans

Bravo-Plaza, Ignacio; Hernández‐González, Miguel; Pinar, Mario; Dı́az, José Fernando; Peñalva, Miguel

doi:10.1016/j.bbamcr.2019.118551

Cited by 14 publications

(23 citation statements)

References 65 publications

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“…PmtC localized, in both wild-type and ∆flbB backgrounds, to structures resembling the endoplasmic reticulum ( Figure 8B). As was described previously for ER proteins such as Sec63 and Sec12 [52,53], nuclear envelopes (NE in Figure 8B) as well as a faint network of interconnected tubules and patches (P) could be discerned in correlation with the predicted function of PmtC as a protein O-mannosyltransferase localized in the ER. Indeed, the induction of the unfolded protein response (UPR) and inhibition of growth triggered by the addition of 8 mM dithiothreitol (DTT) was accompanied by a relocalization of PmtC to bright and bigger spots ( Figure 8C), as was described previously by Markina-Iñarrairaegui and colleagues for Sec63 [52].…”

Section: Substitution Of Proline In Position 282 Of Pmtc Causes An Acsupporting

confidence: 74%

Identification and Characterization of Aspergillus nidulans Mutants Impaired in Asexual Development under Phosphate Stress

Otamendi

Espeso

Etxebeste

2019

Cells

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The transcription factor BrlA plays a central role in the production of asexual spores (conidia) in the fungus Aspergillus nidulans. BrlA levels are controlled by signal transducers known collectively as UDAs. Furthermore, it governs the expression of CDP regulators, which control most of the morphological transitions leading to the production of conidia. In response to the emergence of fungal cells in the air, the main stimulus triggering conidiation, UDA mutants such as the flbB deletant fail to induce brlA expression. Nevertheless, ΔflbB colonies conidiate profusely when they are cultured on a medium containing high H2PO4− concentrations, suggesting that the need for FlbB activity is bypassed. We used this phenotypic trait and an UV-mutagenesis procedure to isolate ΔflbB mutants unable to conidiate under these stress conditions. Transformation of mutant FLIP166 with a wild-type genomic library led to the identification of the putative transcription factor SocA as a multicopy suppressor of the FLIP (Fluffy, aconidial, In Phosphate) phenotype. Deregulation of socA altered both growth and developmental patterns. Sequencing of the FLIP166 genome enabled the identification and characterization of PmtCP282L as the recessive mutant form responsible for the FLIP phenotype. Overall, results validate this strategy for identifying genes/mutations related to the control of conidiation.

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Section: Substitution Of Proline In Position 282 Of Pmtc Causes An Acsupporting

confidence: 74%

Identification and Characterization of Aspergillus nidulans Mutants Impaired in Asexual Development under Phosphate Stress

Otamendi

Espeso

Etxebeste

2019

Cells

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“…Impressively, all proteins essential for cargo biogenesis were indeed present in the proteome analyzed. The only exception is the product of AN11127, which was recently reported as the Sec12 protein of A. nidulans [ 52 ]. However, to our opinion, AN11127 might not be an orthologous protein to the Sec12 protein, which in yeast acts as an essential guanine nucleotide exchange factor (GEF) for activating Sar1p and initiation of COPII vesicle formation.…”

Section: Resultsmentioning

confidence: 99%

Profile of Membrane Cargo Trafficking Proteins and Transporters Expressed under N Source Derepressing Conditions in Aspergillus nidulans

Dimou

Georgiou

Sarantidi

et al. 2021

JoF

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Solute and ion transporters are proteins essential for cell nutrition, detoxification, signaling, homeostasis and drug resistance. Being polytopic transmembrane proteins, they are co-translationally inserted and folded into the endoplasmic reticulum (ER) of eukaryotic cells and subsequently sorted to their final membrane destination via vesicular secretion. During their trafficking and in response to physiological/stress signals or prolonged activity, transporters undergo multiple quality control processes and regulated turnover. Consequently, transporters interact dynamically and transiently with multiple proteins. To further dissect the trafficking and turnover mechanisms underlying transporter subcellular biology, we herein describe a novel mass spectrometry-based proteomic protocol adapted to conditions allowing for maximal identification of proteins related to N source uptake in A. nidulans. Our analysis led to identification of 5690 proteins, which to our knowledge constitutes the largest protein dataset identified by omics-based approaches in Aspergilli. Importantly, we detected possibly all major proteins involved in basic cellular functions, giving particular emphasis to factors essential for membrane cargo trafficking and turnover. Our protocol is easily reproducible and highly efficient for unearthing the full A. nidulans proteome. The protein list delivered herein will form the basis for downstream systematic approaches and identification of protein–protein interactions in living fungal cells.

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“…In sharp contrast, the reporter accumulated in ER membranes in sarA6 cells induced with sucrose and shifted to 37°C (Figure 3A). This accumulation in the ER was noticeable by the conspicuous labeling of the network of peripheral strands and nuclear envelopes that constitute the A. nidulans ER, 30,31 which was best visualized in series of optical sections (Figure 3A). EglC::GFP::GPI accumulation in nuclei and strands was relatively uniform.…”

Section: Resultsmentioning

confidence: 99%

“…We next tested if EglC::GFP::GPI accumulates in the ER upon imposing an ER exit block using sarA6 , a conditional mutation in the gene encoding SarA SAR1 , the master regulator of the formation of COPII vesicles bound for the Golgi 29,30 . At 28°C, the localization of EglC::GFP::GPI in sarA6 cells resembled the wild type (Suppl.…”

Section: Resultsmentioning

confidence: 99%

Tracking exocytosis of a GPI‐anchored protein in Aspergillus nidulans

Peñalva

Moscoso-Romero

Hernández‐González

2020

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Secretion of the glycosylphosphatidylinositol‐anchored protein (GPI‐AP) EglC was investigated in the filamentous fungus Aspergillus nidulans, exploiting a sucrose‐inducible promoter to conditionally express the protein in cells blocked at different steps of exocytosis. EglC is delivered to the cell surface in a polarized fashion, but appears to redistribute rapidly toward apico‐distal regions. Inactivation of SarASar1 mediating COPII vesicle biogenesis resulted in the accumulation of EglC in the endoplasmic reticulum (ER) but, rather than concentrating in ER‐exit‐sites, the reporter labeled the ER uniformly. Abnormal posttranslational modifications of EglC were detected in sarAts and sed5ts mutants, suggesting that blocking COPII biogenesis or traffic in the ER/Golgi interface might affect GPI remodeling. EglC delivery to the plasma membrane requires, besides Golgi function, the TRAPPII complex mediating the biogenesis of RAB11 secretory vesicles at the TGN, but is unaffected by the absence of RAB5, the key regulator of early endosome biogenesis/maturation. Thus, unlike the soluble extracellular enzyme inulinase, EglC is directly delivered from the TGN to the plasma membrane without involvement of endosomes. We conclude that in A. nidulans, GPI‐APs follow a direct secretory pathway from the ER to the plasma membrane.

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Identification of the guanine nucleotide exchange factor for SAR1 in the filamentous fungal model Aspergillus nidulans

Cited by 14 publications

References 65 publications

Identification and Characterization of Aspergillus nidulans Mutants Impaired in Asexual Development under Phosphate Stress

Identification and Characterization of Aspergillus nidulans Mutants Impaired in Asexual Development under Phosphate Stress

Profile of Membrane Cargo Trafficking Proteins and Transporters Expressed under N Source Derepressing Conditions in Aspergillus nidulans

Tracking exocytosis of a GPI‐anchored protein in Aspergillus nidulans

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