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- Beskow, Anne, et al.
(författare)
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A conserved unfoldase activity for the p97 AAA-ATPase in proteasomal degradation
- 2009
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 394:4, s. 732-46
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Tidskriftsartikel (refereegranskat)abstract
- The multifunctional AAA-ATPase p97 is one of the most abundant and conserved proteins in eukaryotic cells. The p97/Npl4/Ufd1 complex dislocates proteins that fail the protein quality control in the endoplasmic reticulum to the cytosol where they are subject to degradation by the ubiquitin/proteasome system. Substrate dislocation depends on the unfoldase activity of p97. Interestingly, p97 is also involved in the degradation of specific soluble proteasome substrates but the exact mode of action of p97 in this process is unclear. Here, we show that both the central pore and ATPase activity of p97 are necessary for the degradation of cytosolic ubiquitin-fusion substrates. Addition of a flexible extended C-terminal peptide to the substrate relieves the requirement for p97. Deletion mapping reveals a conserved length dependency of 20 residues for the peptide, which allows p97-independent degradation to occur. Our results suggest that initiation of unfolding may be more complex than previously anticipated and that the 19S regulatory complex of the proteasome can require preprocessing of highly folded, ubiquitylated substrates by the p97(Ufd1/Npl4) complex. Our data provide an explanation for the observation that p97 is only essential for a subpopulation of soluble substrates and predict that a common characteristic of soluble p97-dependent substrates is the lack of an initiation site to facilitate unfolding by the 26S proteasome.
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| 3. |
- Beskow, Anne, et al.
(författare)
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Comparative analysis of regulatory transcription factors in Schizosaccharomyces pombe and budding yeasts
- 2006
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Ingår i: Yeast. - : Wiley. - 0749-503X .- 1097-0061. ; 23:13, s. 929-935
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Tidskriftsartikel (refereegranskat)abstract
- Regulatory transcription factors (rTFs), which bind specific DNA sequences in the regulatory regions of genes and subsequently activate or repress transcription, play a central role in programming genomic expression. The number of rTFs in a species might therefore reflect its functional complexity. For simple organisms like yeast, a relatively small number of rTFs might be expected that is fairly constant between yeast species. We show that the budding yeast, Saccharomyces cerevisiae, contains 201 rTfs, which is one of the largest rTF numbers found in yeast species for which genome sequences are available. This is a much higher number than the 129 rTFs found in the fission yeast, Schizosaccharomyces pombe, which is currently the yeast with the lowest number of rTFs. Comparative analysis of several different budding yeast species shows that most of the 'extra' rTFs found in S. cerevisiae were probably acquired as a result of a whole genome duplication (WGD) event that occurred in an ancestor of a subset of budding yeast species. However, we also show that budding yeast species that have not been affected by the WGD contain a greater number of rTFs than S. pombe (mean = 145). Thus, two or more mechanisms have led to the 60% increase in rTFs in S. cerevisiae compared to S. pombe. This difference may correlate with a more extensive functional divergence in budding yeasts compared to fission yeasts. The relatively small number of rTFs in S. pombe make this organism an attractive model for global studies of mechanisms that programme gene expression.
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- Beskow, Jonas, et al.
(författare)
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Preliminary cross-cultural evaluation of expressiveness in synthetic faces
- 2004
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Ingår i: Affective Dialogue Systems, Proceedings. - Berlin : SPRINGER-VERLAG. - 3540221433 ; , s. 301-304
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Konferensbidrag (refereegranskat)abstract
- This paper reports the results of a preliminary cross-evaluation experiment run in the framework of the European research project PF-Star(1), with the double I aim of evaluating the possibility of exchanging FAP data between the involved sites and assessing the-adequacy of the emotional facial gestures performed by talking heads. The results provide initial insights in the way people belonging to various cultures-react to natural and synthetic facial expressions produced in different cultural settings, and in the potentials and limits of FAP data exchange.
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| 5. |
- Beskow, Kristina, et al.
(författare)
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A new approach for the study of slag-metal interface in steelmaking
- 2006
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Ingår i: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 33:1, s. 74-80
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Tidskriftsartikel (refereegranskat)abstract
- The main focus of the present work was to develop a sampler to obtain the physical description of the slag-metal interface in the presence of bulk flow. Industrial trial experiments were carried out in the ladles at Uddeholm Tooling, Hagfors, Sweden using the designed sampler. Samples of the slag-metal interface were successfully taken in both gas stirring and induction stirring modes. The similarities of the appearance as well as the micrographs of the samples suggested that the slag-metal interfaces in the two stirring modes were very similar except in the open eye area. In the case of both stirring modes, metal droplets were found in the slag bulk. On the other hand, no appreciable amount of slag was detected in the metal bulk. Further systematic investigation using a large number of samples is required to obtain a quantitative description of the interface. © 2006 Institute of Materials, Minerals and Mining.
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| 6. |
- Dayal, P., et al.
(författare)
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Study of slag/metal interface in ladle treatment
- 2006
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Ingår i: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 33:6, s. 454-464
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Tidskriftsartikel (refereegranskat)abstract
- In order to gain an insight into the mixing behaviour of slag and metal under different stirring conditions, samples of slag/metal interface were collected from an industrial 65 ton ladle furnace using a new sampling technique. Different stirring conditions and sampling positions in the ladle were chosen. Complementary cold model experiments were also performed. The experimental results strongly suggested that the shear force between the two liquids played an important role in slag-metal mixing. Evidence for the existence of slag droplets each surrounded by a very thin metal film was found in the samples taken under both gas stirred and induction stirred conditions. This observation strongly suggested that slag-metal system behaved similarly as oil-water system, wherein, the shear force owing to the bulk flow led to a packed 'sphere bed' of oil droplets each coated by a thin water film above the water bath. On the basis of the experimental results, preliminary mathematical models were developed to describe the rate of mass exchange at the slag/metal interface. © 2006 Institute of Materials, Minerals and Mining.
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| 7. |
- Dayal, P., et al.
(författare)
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Study of stag/metal interface in ladle treatment
- 2006
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Ingår i: Ironmaking & steelmaking. - : Informa UK Limited. - 0301-9233 .- 1743-2812. ; 33:6, s. 454-464
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Tidskriftsartikel (refereegranskat)abstract
- In order to gain an insight into the mixing behaviour of slag and metal under different stirring conditions, samples of slag/metal interface were collected from an industrial 65 ton ladle furnace using a new sampling technique. Different stirring conditions and sampling positions in the ladle were chosen. Complementary cold model experiments were also performed. The experimental results strongly suggested that the shear force between the two liquids played an important role in slag-metal mixing. Evidence for the existence of slag droplets each surrounded by a very thin metal film was found in the samples taken under both gas stirred and induction stirred conditions. This observation strongly suggested that slag-metal system behaved similarly as oil-water system, wherein, the shear force owing to the bulk flow led to a packed 'sphere bed' of oil droplets each coated by a thin water film above the water bath. On the basis of the experimental results, preliminary mathematical models were developed to describe the rate of mass exchange at the slag/metal interface.
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