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Source: Autumn view of Slioch from Grudie, Loch Maree, A

Forestry Tags > Tag based links for Budding

The following links have been tagged budding by users just like you, because these resources are off-site we cannot guarantee the accuracy or quality of any third-party information.

Microtubule interactions with the cell cortex causing nuclear movements in Saccharomyces cerevisiae.: The Journal of cell biology, Vol. 149, No. 4. (15 May 2000), pp. 863-874.During mitosis in budding yeast the nucleus first moves to the mother-bud neck and then into the neck. Both movements depend on interactions of cytoplasmic microtubules with the cortex. We investigated the mechanism of these movements in living cells using video analysis of GFP-labeled microtubules in wild-type cells and in EB1 and Arp1 mutants, which are defective in the first and second steps, respectively. We found that nuclear movement to the neck is largely mediated by the capture of microtubule ends at one cortical region at the incipient bud site or bud tip, followed by microtubule depolymerizati on. Efficient microtubule interactions with the capture site require that microtubules be sufficiently long and dynamic to probe the cortex. In contrast, spindle movement into the neck is mediated by microtubule sliding along the bud cortex, which requires dynein and dynactin. Free microtubules can also slide along the cortex of both bud and mother. Capture/shrink age of microtubule ends also contributes to nuclear movement into the neck and can serve as a backup mechanism to move the nucleus into the neck when microtubule sliding is impaired. Conversely, microtubule sliding can move the nucleus into the neck even when capture/shrink age is impaired.

Source: The Journal of cell biology, Vol. 149, No. 4. (15 May 2000), pp. 863-874.
Cortical Num1p interacts with the dynein intermediate chain Pac11p and cytoplasmic microtubules in budding yeast.: The Journal of cell biology, Vol. 152, No. 2. (22 January 2001), pp. 251-262.Num1p, a cortical 313-kD protein, controls cytoplasmic microtubule (cMT) functions and nuclear migration through the bud neck in anaphase cells. A green fluorescent protein (GFP)-Num1p fusion protein localizes at the bud tip and the distal mother pole of living cells, apparently forming cMT capture sites at late anaphase. In addition, galactose-indu ced GFP-Num1p is seen at the bud neck and in lateral regions of the mother cortex. The bud tip location of Num1p depends on Bni1p but does not require Kar9p, Dyn1p, or cMTs, whereas cMT contacts with polar Num1p dots are reduced in cells lacking Dyn1p. Num1p associates with the dynein intermediate chain Pac11p in the presence of Dyn1p, and with the alpha-tubulin Tub3p, as shown by coimmune precipitation of tagged proteins. Num1p also forms a complex with Bni1p and Kar9p, although Num1p is not required for Bni1p- and Kar9p-dependen t nuclear migration to the bud neck in preanaphase cells.Our data suggest that Num1p controls nuclear migration during late anaphase by forming dynein-interac ting cortical cMT capture sites at both cellular poles. In addition, Num1p may transiently cooperate with an associated Bni1p-Kar9p complex at the bud tip of early anaphase cells.

Source: The Journal of cell biology, Vol. 152, No. 2. (22 January 2001), pp. 251-262.
Yeast Num1p associates with the mother cell cortex during S/G2 phase and affects microtubular functions.: The Journal of cell biology, Vol. 131, No. 4. (November 1995), pp. 1003-1014.The NUM1 gene is involved in the control of nuclear migration in Saccharomyces cerevisiae. The content of NUM1 mRNA fluctuates during the cell cycle, reaching a maximum at S/G2 phase, and the translation product Num1p associates with the cortex of mother cells mainly during S, G2, and mitosis, as seen by indirect immunofluoresc ence. The nuclear spindle in NUM1-deficient large-budded cells often fails to align along the mother/bud axis, while abnormally elongated astral microtubules emanate from both spindle pole bodies. A num1 null mutation confers temperature sensitivity to the cold-sensitive alpha-tubulin mutant tub1-1, and shows synthetic lethality with the beta-tubulin mutant alleles tub2-402, tub2-403, tub2-404, and tub2-405. Deletion mapping has defined three functionally important Num1p regions: a potential EF hand Ca2+ binding site, a cluster of potential phosphorylatio n sites and a pleckstrin homology domain. The latter domain appears to be involved in targeting Num1p to the mother cell cortex. Our data suggest that the periodically expressed NUM1 gene product controls nuclear migration by affecting astral microtubule functions.

Source: The Journal of cell biology, Vol. 131, No. 4. (November 1995), pp. 1003-1014.
Photoactivatab le GFP tagging cassettes for protein-tracki ng studies in the budding yeast Saccharomyces cerevisiae.: Yeast (Chichester, England), Vol. 25, No. 9. (September 2008), pp. 651-659.Yeast cell biologists use a variety of fluorescent protein tags for determining protein localization and for measuring protein dynamics using fluorescence recovery after photobleaching (FRAP). Although many modern fluorescent proteins, such as those with photoactivatab le and photoconvertib le characteristic s, have been developed, none has been exploited for studies in budding yeast. We describe here the construction of yeast-tagging vectors containing photoactivatab le green fluorescent protein (PA-GFP) for analysis of protein behaviour. We tagged two yeast proteins, Erg6p and Num1p, with PA-GFP and demonstrated specific photoactivatio n of the fusion proteins in live cells. Fluorescence intensity measurements showed that a short 5 s exposure to 413 nm light is sufficient to produce the maximum level of activated GFP fluorescence. Local photoactivatio n of cortical Num1p-PA-GFP showed movement of the marked proteins, providing new insights into the behaviour of Num1p at the cell cortex. Since photoactivatio n can be achieved using standard mercury arc illumination, the PA-GFP tag represents a convenient and economical way to determine protein dynamics in the cell. Thus, the tagging modules should facilitate protein-tracki ng studies in a wide variety of cell biological processes in yeast.

Source: Yeast (Chichester, England), Vol. 25, No. 9. (September 2008), pp. 651-659.
The effects of molecular noise and size control on variability in the budding yeast cell cycle: Nature, Vol. 448, No. 7156., pp. 947-951.

Source: Nature, Vol. 448, No. 7156., pp. 947-951.
Envelope Lipids Regulate the In Vitro Assembly of the HIV-1 Capsid: Biophys. J., Vol. 94, No. 2. (15 January 2008), pp. L8-10.During maturation of type 1 human immunodeficien cy virus, a fraction of the capsid protein (CA) molecules in the budding virus particle form a conical capsid. However, the location and role of the remaining CA molecules are unknown. It has been recently reported that the C-terminal domain of CA is able to interact with lipid bilayers, suggesting that the CA molecules that do not form the capsid could be attached to the lipid envelope of the virus. Here, we have studied in vitro the effect of different envelope lipids on the CA polymerization process. Our results show that the negatively charged lipids phosphatidic acid and phosphatidylse rine partially inhibit CA polymerization , whereas the nonbilayer forming lipid phosphatidylet hanolamine facilitates CA assembly. These results suggest that specific lipids of the viral envelope could have a regulatory role in the maturation of type 1 human immunodeficien cy virus. 10.1529/biophy sj.107.118083

Source: Biophys. J., Vol. 94, No. 2. (15 January 2008), pp. L8-10.
Efficient and Specific Rescue of Human Immunodeficien cy Virus Type 1 Budding Defects by a Nedd4-Like Ubiquitin Ligase: J. Virol., Vol. 82, No. 10. (15 May 2008), pp. 4898-4907.To exit infected cells, human immunodeficien cy virus type 1 (HIV-1) exploits the vacuolar protein-sortin g pathway by engaging Tsg101 and ALIX through PTAP and LYPxnL late assembly (L) domains. In contrast, less-complex retroviruses often use PPxY L domains to recruit Nedd4 family ubiquitin ligases. Although HIV-1 Gag lacks PPxY motifs, we now show that the budding of various HIV-1 L-domain mutants is dramatically enhanced by ectopic Nedd4-2s, a native isoform with a truncated C2 domain. The effect of Nedd4-2s on HIV-1 budding required a catalytically active HECT domain and was specific, since other Nedd4 family proteins showed little activity and an unrelated retrovirus was not rescued. The residual C2 domain of Nedd4-2s was critical for the enhancement of HIV-1 budding and for the association of Nedd4-2s with Gag, as reflected by its incorporation into virus-like particles. Interestingly, the incorporation of Nedd4-2s also depended on its active site, indicating that the ability to form a thioester with ubiquitin was required. These data suggest a novel mechanism by which HIV-1 Gag can connect to cellular budding machinery. 10.1128/JVI.02 675-07

Source: J. Virol., Vol. 82, No. 10. (15 May 2008), pp. 4898-4907.
RETROVIRUSES HIV AND MLV ARE ENRICHED IN PHOSPHOINOSITI DES.: Journal of virology (17 September 2008)Retroviru ses acquire a lipid envelope during budding from the membrane of their hosts. Therefore, the composition of this envelope can provide important information about the budding process and its location. Here, we present mass spectrometry analysis of the lipid content of HIV-1 and MLV. The results of this comprehensive survey found that the overall lipid content of these viruses mostly matched that of the plasma membrane, being considerably different from the total lipid content of the cells. However, several lipids are enriched in comparison to plasma membrane: 1) cholesterol, ceramide, and GM3; 2) phosphoinositi des, phosphorylated derivatives of phosphatidylin ositol. Interestingly, microvesicles, which are similar in size to viruses and are also released from the cell periphery, lack phosphoinositi des, suggesting a different budding mechanism/loca tion for these particles than for retroviruses. One phosphoinositi de, PI(4,5)P2, has been implicated in membrane binding by Gag. Consistent with this observation, we found PI(4,5)P2 to be enriched in HIV-1 and that depleting this molecule in cells reduced HIV-1 budding. Analysis of mutant virions mapped the enrichment of PI(4,5)P2 to the matrix domain of HIV Gag. Overall, these results suggest that HIV-1 and other retroviruses bud from cholesterol-ri ch regions of the plasma membrane and exploit matrix/PI(4,5) P2 interactions for particle release from cells.

Source: Journal of virology (17 September 2008)
Yeasts make their mark: Nat Cell Biol, Vol. 5, No. 4. (April 2003), pp. 294-299.

Source: Nat Cell Biol, Vol. 5, No. 4. (April 2003), pp. 294-299.
Astral microtubules are not required for anaphase B in Saccharomyces cerevisiae.: The Journal of cell biology, Vol. 119, No. 2. (October 1992), pp. 379-388.tub2-4 01 is a cold-sensitive allele of TUB2, the sole gene encoding beta-tubulin in the yeast, Saccharomyces cerevisiae. At 18 degrees C, tub2-401 cells are able to assemble spindle microtubules but lack astral microtubules. Under these conditions, movement of the spindle to the bud neck is blocked. However, spindle elongation and chromosome separation are unimpeded and occur entirely within the mother cell. Subsequent cytokinesis produces one cell with two nuclei and one cell without a nucleus. The anucleate daughter can not bud. The binucleate daughter proceeds through another cell cycle to produce a cell with four nuclei and another anucleate cell. With additional time in the cold, the number of nuclei in the nucleated cells continues to increase and the percentage of anucleate cells in the population rises. The results indicate that astral microtubules are needed to position the spindle in the bud neck but are not required for spindle elongation at anaphase B. In addition, cell cycle progression does not depend on the location or orientation of the spindle.

Source: The Journal of cell biology, Vol. 119, No. 2. (October 1992), pp. 379-388.

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