scholarly journals Mechanism of vacuole inheritance

2012 ◽  
Vol 24 (1) ◽  
pp. 105-109
Author(s):  
Fumi Yagisawa
Keyword(s):  
Vacuole Inheritance

scholarly journals The Coiled-Coil Protein VIG1 Is Essential for Tethering Vacuoles to Mitochondria during Vacuole Inheritance of Cyanidioschyzon merolae

2010 ◽  
Vol 22 (3) ◽  
pp. 772-781 ◽  
Author(s):  
Takayuki Fujiwara ◽  
Haruko Kuroiwa ◽  
Fumi Yagisawa ◽  
Mio Ohnuma ◽  
Yamato Yoshida ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Cyanidioschyzon Merolae ◽  
Vacuole Inheritance

scholarly journals A Point Mutation in the Cargo-Binding Domain of Myosin V Affects Its Interaction with Multiple Cargoes

2005 ◽  
Vol 4 (4) ◽  
pp. 787-798 ◽  
Author(s):  
Natasha Pashkova ◽  
Natalie L. Catlett ◽  
Jennifer L. Novak ◽  
Lois S. Weisman
Keyword(s):  
Point Mutation ◽  
Specific Binding ◽  
Secretory Vesicle ◽  
Specific Protein ◽  
Myosin V ◽  
Specific Proteins ◽  
Tight Association ◽  
Vacuole Inheritance ◽  
Vesicle Movement ◽  
Cargo Binding

ABSTRACT Class V myosins move diverse intracellular cargoes, which attach via interaction of cargo-specific proteins to the myosin V globular tail. The globular tail of the yeast myosin V, Myo2p, contains two structural and functional subdomains. Subdomain I binds to the vacuole-specific protein, Vac17p, while subdomain II likely binds to an as yet unidentified secretory vesicle-specific protein. All functions of Myo2p require the tight association of subdomains I and II, which suggests that binding of a cargo to one subdomain may inhibit cargo-binding to a second subdomain. Thus, two types of mutations are predicted to specifically affect a subset of Myo2p cargoes: first are mutations within a cargo-specific binding region; second are mutations that mimic the inhibited conformation of one of the subdomains. Here we analyze a point mutation in subdomain I, myo2-2(G1248D), which is likely to be this latter type of mutation. myo2-2 has no effect on secretory vesicle movement. The secretory vesicle binding site is in subdomain II. However, myo2-2 is impaired in several Myo2p-related functions. While subdomains I and II of myo2-2p tightly associate, there are measurable differences in the conformation of its globular tail. Based solely on the ability to restore vacuole inheritance, a set of intragenic suppressors of myo2-2 were identified. All suppressor mutations reside in subdomain I. Moreover, subdomain I and II interactions occurred in all suppressors, demonstrating the importance of subdomain I and II association for Myo2p function. Furthermore, 3 of the 10 suppressors globally restored all tested defects in myo2-2. This large proportion of global suppressors strongly suggests that myo2-2(G1248) causes a conformational change in subdomain I that simultaneously affects multiple cargoes.

scholarly journals PTC1 Is Required for Vacuole Inheritance and Promotes the Association of the Myosin-V Vacuole-specific Receptor Complex

2009 ◽  
Vol 20 (5) ◽  
pp. 1312-1323 ◽  
Author(s):  
Yui Jin ◽  
P. Taylor Eves ◽  
Fusheng Tang ◽  
Lois S. Weisman
Keyword(s):  
Protein Phosphatase ◽  
Adaptor Proteins ◽  
Specific Receptor ◽  
Myosin V ◽  
Steady State Levels ◽  
Specific Receptors ◽  
Vacuole Inheritance ◽  
Ash1 Mrna ◽  
Cellular Components ◽  
Cortical Endoplasmic Reticulum

Organelle inheritance occurs during cell division. In Saccharomyces cerevisiae, inheritance of the vacuole, and the distribution of mitochondria and cortical endoplasmic reticulum are regulated by Ptc1p, a type 2C protein phosphatase. Here we show that PTC1/VAC10 controls the distribution of additional cargoes moved by a myosin-V motor. These include peroxisomes, secretory vesicles, cargoes of Myo2p, and ASH1 mRNA, a cargo of Myo4p. We find that Ptc1p is required for the proper distribution of both Myo2p and Myo4p. Surprisingly, PTC1 is also required to maintain the steady-state levels of organelle-specific receptors, including Vac17p, Inp2p, and Mmr1p, which attach Myo2p to the vacuole, peroxisomes, and mitochondria, respectively. Furthermore, Vac17p fused to the cargo-binding domain of Myo2p suppressed the vacuole inheritance defect in ptc1Δ cells. These findings suggest that PTC1 promotes the association of myosin-V with its organelle-specific adaptor proteins. Moreover, these observations suggest that despite the existence of organelle-specific receptors, there is a higher order regulation that coordinates the movement of diverse cellular components.

scholarly journals p21-Activated Kinases Cla4 and Ste20 Regulate Vacuole Inheritance in Saccharomyces cerevisiae

2009 ◽  
Vol 8 (4) ◽  
pp. 560-572 ◽  
Author(s):  
Clinton R. Bartholomew ◽  
Christopher F. J. Hardy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Daughter Cell ◽  
Dependent Manner ◽  
Myosin V ◽  
M Phase ◽  
Mother And Daughter ◽  
Specific Proteins ◽  
Vacuole Inheritance ◽  
Specific Degradation ◽  
Segregation Structure

ABSTRACT Each time Saccharomyces cerevisiae cells divide they ensure that both the mother and daughter cell inherit a vacuole by actively transporting a portion of the vacuole into the bud. As the mother cell begins budding, a tubular and vesicular segregation structure forms that is transported into the bud by the myosin V motor Myo2, which is bound to the vacuole-specific myosin receptor, Vac17 (41, 59, 70, 79). Upon arriving in the bud the segregation structure is resolved to found the daughter vacuole. The mechanism that regulates segregation structure resolution in a spatially dependent manner is unknown. In addition to resolving the segregation structure, Vac17 is degraded specifically in the bud to provide directionality to vacuole inheritance. It has been proposed that bud-specific degradation of Vac17 is promoted by proteins localized to or activated solely in the bud (77). The p21-activated kinases (PAKs) Cla4 and Ste20 are localized to and activated in the bud. Here we report that Cla4 is localized to the segregation structure just prior to segregation structure resolution, and cells lacking PAK function fail to resolve the segregation structure. Overexpression of either Cla4 or Ste20 inhibited vacuole inheritance and this inhibition was suppressed by the expression of nondegradable VAC17. Finally, PAK activity was required for Vac17 degradation in late M phase and CLA4 overexpression promoted Vac17 degradation. We propose that Cla4 and Ste20 are bud-specific proteins that play roles in both segregation structure resolution and the degradation of Vac17.

scholarly journals G-protein ligands inhibit in vitro reactions of vacuole inheritance.

1994 ◽  
Vol 126 (1) ◽  
pp. 87-97 ◽  
Author(s):  
A Haas ◽  
B Conradt ◽  
W Wickner
Keyword(s):  
Alkaline Phosphatase ◽  
Vacuole Membrane ◽  
Protein Ligands ◽  
Vacuole Fusion ◽  
Proteinase A ◽  
Membrane Bound ◽  
Vacuole Inheritance ◽  
Cytosolic Factors

During budding in Saccharomyces cerevisiae, maternal vacuole material is delivered into the growing daughter cell via tubular or vesicular structures. One of the late steps in vacuole inheritance is the fusion in the bud of vesicles derived from the maternal vacuole. This process has been reconstituted in vitro and requires isolated vacuoles, a physiological temperature, cytosolic factors, and ATP (Conradt, B., J. Shaw, T. Vida, S. Emr, and W. Wickner. 1992. J. Cell Biol. 119:1469-1479). We now report a simple and reliable assay to quantify vacuole-to-vacuole fusion in vitro. This assay is based on the maturation and activation of vacuole membrane-bound pro-alkaline phosphatase by vacuolar proteinase A after vacuole-to-vacuole fusion. In vitro fusion allowed maturation of 30 to 60% of pro-alkaline phosphatase. Vacuoles prepared from a mutant defective in vacuole inheritance in vivo (vac2-1) were inactive in this assay. Vacuole fusion in vitro required a vacuole membrane potential. Inhibition by nonhydrolyzable guanosine derivatives, mastoparans, and benzalkonium chloride suggest that GTP-hydrolyzing G proteins may play a key role in the in vitro fusion events.

scholarly journals A truncated form of the Pho80 cyclin redirects the Pho85 kinase to disrupt vacuole inheritance in S. cerevisiae.

1995 ◽  
Vol 130 (4) ◽  
pp. 835-845 ◽  
Author(s):  
T A Nicolson ◽  
L S Weisman ◽  
G S Payne ◽  
W T Wickner
Keyword(s):  
Transcription Factors ◽  
S Phase ◽  
Complete Loss ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Truncated Form ◽  
Pho Pathway ◽  
G2 Phase ◽  
Vacuole Inheritance ◽  
Delta Cells

Partitioning of the vacuole during cell division in Saccharomyces cerevisiae begins during early S phase and ends in late G2 phase before the yeast nucleus migrates into the bud neck. We have isolated and characterized a new mutant, vac5-1, which is defective in vacuole segregation. Cells with the vac5-1 mutation can form large buds without vacuoles. The VAC5 gene was cloned and is identical to PHO80. PHO80 encodes a cyclin which acts in a complex with a cdc-like kinase, PHO85, as a negative regulator of two transcription factors (PHO2 and PHO4) that govern the expression of metabolic phosphatases. The vacuole inheritance defect in vac5-1 cells is dependent on the presence of the Pho85 kinase and its targets Pho4p and Pho2p. As with other alleles of PHO80, phosphatase levels are elevated in vac5-1 mutants. A suppressor, the COOH-terminal half of the Gal11 transcription factor, rescues the vac5-1 phenotype of defective vacuole inheritance without altering the vac5-1 phenotype of elevated phosphatase levels. In addition, neither maximal nor minimal levels of expression of the inducible "PHO" system phosphatases causes a vacuole inheritance defect. Though vac5-1 is recessive, pho80 delta or pho85 delta strains do not show a defect in vacuole inheritance, suggesting that vac5-1 is not a complete loss-of-function allele. Sequence analysis shows that the vac5-1 allele encodes a truncated form of the Pho80 cyclin and overexpression of vac5-1 in pho80 delta cells causes a vacuole inheritance defect. We conclude that the vac5-1 allele directs the Pho85 kinase to regulate, via transcription factors Pho4 and Pho2, genes that affect vacuole inheritance but which are not known to be under normal PHO pathway control.

scholarly journals A Heterodimer of Thioredoxin and IB2 Cooperates with Sec18p (NSF) to Promote Yeast Vacuole Inheritance

1997 ◽  
Vol 136 (2) ◽  
pp. 299-306 ◽  
Author(s):  
Zuoyu Xu ◽  
Andreas Mayer ◽  
Eric Muller ◽  
William Wickner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Early Stage ◽  
Redox Chemistry ◽  
Soluble Proteins ◽  
S Phase ◽  
Cell Extracts ◽  
Vacuole Inheritance ◽  
Cytosolic Inhibitor

Early in S phase, the vacuole (lysosome) of Saccharomyces cerevisiae projects a stream of vesicles and membranous tubules into the bud where they fuse and establish the daughter vacuole. This inheritance reaction can be studied in vitro with isolated vacuoles. Rapid and efficient homotypic fusion between saltwashed vacuoles requires the addition of only two purified soluble proteins, Sec18p (NSF) and LMA1, a novel heterodimer with a thioredoxin subunit. We now report the identity of the second subunit of LMA1 as IB2, a previously identified cytosolic inhibitor of vacuolar proteinase B. Both subunits are needed for efficient vacuole inheritance in vivo and for the LMA1 activity in cell extracts. Each subunit acts via a novel mechanism, as the thioredoxin subunit is not acting through redox chemistry and LMA1 is still needed for the fusion of vacuoles which do not contain proteinase B. Both Sec18p and LMA1 act at an early stage of the in vitro reaction. Though LMA1 does not stimulate Sec18p-mediated Sec17p release, LMA1 cannot fulfill its function before Sec18p. Upon Sec17p/Sec18p action, vacuoles become labile but are rapidly stabilized by LMA1. The action of LMA1 and Sec18p is thus coupled and ordered. These data establish LMA1 as a novel factor in trafficking of yeast vacuoles.

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