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F Brandizzi

Publications and source records attributed to F Brandizzi.

7 recordsLinked to original sources
PubMed2004

Arabidopsis thaliana expresses multiple Golgi-localised nucleotide-sugar transporters related to GONST1.

Transport of nucleotide-sugars across the Golgi membrane is required for the lumenal synthesis of a variety of essential cell surface components, and is mediated by nucleotide sugar transporters (NSTs) which are members of the large drug/metabolite superfamily of transporters. Despite the importance of these proteins in plants, so far only two have been described, GONST1 and AtUTr1 from Arabidopsis thaliana. In this work, our aim was to identify further Golgi nucleotide-sugar transporters from Arabidopsis. On the basis of their sequence similarity to GONST1, we found four additional proteins, which we named GONST2, 3, 4 and 5. These putative NSTs were grouped into three clades: GONST2 with GONST1; GONST3 with GONST4; and GONST5 with six further uncharacterized proteins. Transient expression in tobacco cells of a member of each clade, fused to the Green Fluorescent Protein (GFP), suggested that all these putative NSTs are localised in the Golgi. To obtain evidence for nucleotide sugar transport activity, we expressed these proteins, together with the previously characterised GONST1, in a GDP-mannose transport-defective yeast mutant (vrg4-2). We tested the transformants for rescue of two phenotypes associated with this mutation: sensitivity to hygromycin B and reduced glycosylation of extracellular chitinase. GONST1 and GONST2 complemented both phenotypes, indicating that GONST2, like the previously characterized GONST1, is a GDP-mannose transporter. GONST3, 4 and 5 also rescued the antibiotic sensitivity, but not the chitinase glycosylation defect, suggesting that they can also transport GDP-mannose across the yeast Golgi membrane but with a lower efficiency. RT-PCR and analysis of Affymetrix data revealed partially overlapping patterns of expression of GONST1-5 in a variety of organs. Because of the differences in ability to rescue the vrg4 - 2 phenotype, and the different expression patterns in plant organs, we speculate that GONST1 and GONST2 are both GDP-mannose transporters, whereas GONST3, GONST4 and GONST5 may transport other nucleotide-sugars in planta.

Amino Acid Sequence↗
PubMed2004

Dynamics of proteins in Golgi membranes: comparisons between mammalian and plant cells highlighted by photobleaching techniques.

In less than a decade the green fluorescent protein (GFP) has become one of the most popular tools for cell biologists for the study of dynamic processes in vivo. GFP has revolutionised the scientific approach for the study of vital organelles, such as the Golgi apparatus. As Golgi proteins can be tagged with GFP, in most cases without altering their targeting and function, it is a great substitute to conventional dyes used in the past to highlight this compartment. In this review, we cover the application of GFP and its spectral derivatives in the study of Golgi dynamics in mammalian and plant cells. In particular, we focus on the technique of selective photobleaching known as fluorescence recovery after photobleaching, which has successfully shed light on essential differences in the biology of the Golgi apparatus in mammalian and plant cells.

Animals↗
PubMed2004

GFP is the way to glow: bioimaging of the plant endomembrane system.

It is less than a decade that the green fluorescent protein (GFP) and its spectral variants have changed the approach to studying the dynamics of the plant secretory pathway. GFP technology has in fact shed new light on secretory events by allowing bioimaging in vivo right to the heart of a plant cell. This review highlights exciting discoveries and the most recent developments in the understanding of morphology and dynamics of the plant secretory pathway achieved with the application of fluorescent proteins.

Biological Transport, Active↗
PubMed2001

Cytoplasmic illuminations: in planta targeting of fluorescent proteins to cellular organelles.

Use of the jellyfish green-fluorescent protein as an in vivo reporter is in the process of revolutionising plant cell biology. By fusing the protein to specific targeting peptides or to sequences of complete proteins, it is now possible to observe the location, structure, and dynamics of a number of intracellular organelles over extended periods of time. In this review we discuss the most recent developments and unexpected results originating from the targeting of this unique protein and its derivatives to elements of the cytoskeleton and to membrane-bounded organelles in a range of plant cell types.

Arabidopsis↗
PubMed2001

A vacuolar sorting domain may also influence the way in which proteins leave the endoplasmic reticulum.

Protein sorting to plant vacuoles is known to be dependent on a considerable variety of protein motifs recognized by a family of sorting receptors. This can involve either traffic from the endoplasmic reticulum (ER) through the Golgi apparatus or direct ER-to-vacuole transport. Barley aspartic protease (Phytepsin) was shown previously to reach the vacuole via trafficking through the Golgi apparatus. Here we show that Phytepsin normally exits the ER in a COPII-mediated manner, because the Phytepsin precursor accumulates in the ER upon specific inhibition of the formation of COPII vesicles in vivo. Phytepsin differs from its yeast and mammalian counterparts by the presence of a saposin-like plant-specific insert (PSI). Deletion of this domain comprising 104 amino acids causes efficient secretion of the truncated molecule (Phytepsin Delta PSI) without affecting the enzymatic activity of the enzyme. Interestingly, deletion of the PSI also changes the way in which Phytepsin exits the ER. Inhibition of COPII vesicle formation causes accumulation of the Phytepsin precursor in the ER but has no effect on the secretion of Phytepsin Delta PSI. This suggests either that vacuolar sorting commences at the ER export step and involves recruitment into COPII vesicles or that the PSI domain carries two signals, one for COPII-dependent export from the ER and one for vacuolar delivery from the Golgi. The relevance of these observations with respect to the bulk flow model of secretory protein synthesis is discussed.

Animals↗
PubMed1999

Endomembranes and vesicle trafficking.

Over the past year extensive analyses of the accumulated data on the structural and functional organisation of the endomembrane system and vesicular trafficking in higher plants have shown it to be far more complex than previously anticipated. The availability of molecular tools combined with new opportunities to visualise endomembrane dynamics in vivo will allow better understanding of the fundamental processes underlying the complexity of endomembrane behaviour and vesicular trafficking.

Biological Transport↗