Saccharomyces cerevisiae Apl2p, a homologue of the mammalian clathrin AP beta subunit, plays a role in clathrin-dependent Golgi functions

Clathrin-coated vesicles mediate selective intracellular protein traffic from the plasma membrane and the trans-Golgi network. At these sites, clathrin-associated protein (AP) complexes have been implicated in both clathrin coat assembly and collection of cargo into nascent vesicles. We have found a gene on yeast chromosome XI that encodes a homologue of the mammalian AP beta subunits. Disruptions of this gene, APl2, and a previously identified beta homologue, APl1, have been engineered in cells expressing wild-type (CHC1) or temperature sensitive (chc1-ts) alleles of the clathrin heavy chain gene. APl1 or APl2 disruptions (apl1 delta or apl2 delta) yield no discernable phenotypes in CHC1 strains, indicating that the Apl proteins are not essential for clathrin function. However, the apl2 delta, but not the apl1 delta, allele enhances the growth and alpha-factor pheromone maturation defects of chc1-ts cells. Disruption of APl2 also partially suppresses the vacuolar sorting defect that occurs in chc1-ts cells immediately after imposition of the non-permissive temperature. These Golgi-specific effects of apl2 delta in chc1-ts cells provide evidence that Apl2p is a component of an AP complex that interacts with clathrin at the Golgi apparatus.

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Tracking the Cartoon mouse phenotype: Hemopexin domain–dependent regulation of MT1-MMP pericellular collagenolytic activity

Journal of Biological Chemistry ◽

10.1074/jbc.ra117.001503 ◽

2018 ◽

Vol 293 (21) ◽

pp. 8113-8127 ◽

Cited By ~ 3

Author(s):

Moustafa Sakr ◽

Xiao-Yan Li ◽

Farideh Sabeh ◽

Tamar Y. Feinberg ◽

John J. G. Tesmer ◽

...

Keyword(s):

Cell Surface ◽

Critical Role ◽

Collagenolytic Activity ◽

Temperature Sensitive ◽

Type I ◽

Permissive Temperature ◽

Sensitive Mutant ◽

Temperature Sensitive Mutant ◽

Golgi Network ◽

Hemopexin Domain

Following ENU mutagenesis, a phenodeviant line was generated, termed the “Cartoon mouse,” that exhibits profound defects in growth and development. Cartoon mice harbor a single S466P point mutation in the MT1-MMP hemopexin domain, a 200-amino acid segment that is thought to play a critical role in regulating MT1-MMP collagenolytic activity. Herein, we demonstrate that the MT1-MMPS466P mutation replicates the phenotypic status of Mt1-mmp–null animals as well as the functional characteristics of MT1-MMP−/− cells. However, rather than a loss-of-function mutation acquired as a consequence of defects in MT1-MMP proteolytic activity, the S466P substitution generates a misfolded, temperature-sensitive mutant that is abnormally retained in the endoplasmic reticulum (ER). By contrast, the WT hemopexin domain does not play a required role in regulating MT1-MMP trafficking, as a hemopexin domain-deletion mutant is successfully mobilized to the cell surface and displays nearly normal collagenolytic activity. Alternatively, when MT1-MMPS466P–expressing cells are cultured at a permissive temperature of 25 °C that depresses misfolding, the mutant successfully traffics from the ER to the trans-Golgi network (ER → trans-Golgi network), where it undergoes processing to its mature form, mobilizes to the cell surface, and expresses type I collagenolytic activity. Together, these analyses define the Cartoon mouse as an unexpected gain-of-abnormal function mutation, wherein the temperature-sensitive mutant phenocopies MT1-MMP−/− mice as a consequence of eliciting a specific ER → trans-Golgi network trafficking defect.

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Yeast Gga Coat Proteins Function with Clathrin in Golgi to Endosome Transport

Molecular Biology of the Cell ◽

10.1091/mbc.12.6.1885 ◽

2001 ◽

Vol 12 (6) ◽

pp. 1885-1896 ◽

Cited By ~ 103

Author(s):

G. Costaguta ◽

C. J. Stefan ◽

E. S. Bensen ◽

S. D. Emr ◽

G. S. Payne

Keyword(s):

Yeast Cells ◽

Chain Gene ◽

Temperature Sensitive ◽

Coat Proteins ◽

Trans Golgi Network ◽

Clathrin Adaptor ◽

Sensitive Allele ◽

Golgi Network ◽

In Cells

Gga proteins represent a newly recognized, evolutionarily conserved protein family with homology to the “ear” domain of the clathrin adaptor AP-1 γ subunit. Yeast cells contain two Gga proteins, Gga1p and Gga2p, that have been proposed to act in transport between thetrans-Golgi network and endosomes. Here we provide genetic and physical evidence that yeast Gga proteins function in trans-Golgi network clathrin coats. Deletion of Gga2p (gga2Δ), the major Gga protein, accentuates growth and α-factor maturation defects in cells carrying a temperature-sensitive allele of the clathrin heavy chain gene. Cells carrying eithergga2Δ or a deletion of the AP-1 β subunit gene(apl2Δ) alone are phenotypically normal, but cells carrying both gga2Δ andapl2Δ are defective in growth, α-factor maturation, and transport of carboxypeptidase S to the vacuole. Disruption of bothGGA genes and APL2 results in cells so severely compromised in growth that they form only microcolonies. Gga proteins can bind clathrin in vitro and cofractionate with clathrin-coated vesicles. Our results indicate that yeast Gga proteins play an important role in cargo-selective clathrin-mediated protein traffic from the trans-Golgi network to endosomes.

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A Yeast taf17 Mutant Requires the Swi6 Transcriptional Activator for Viability and Shows Defects in Cell Cycle-Regulated Transcription

Genetics ◽

10.1093/genetics/154.4.1561 ◽

2000 ◽

Vol 154 (4) ◽

pp. 1561-1576

Author(s):

Neil Macpherson ◽

Vivien Measday ◽

Lynda Moore ◽

Brenda Andrews

Keyword(s):

Cell Cycle ◽

Transcriptional Activation ◽

Essential Gene ◽

Temperature Sensitive ◽

Permissive Temperature ◽

Synthetic Lethal ◽

Cycle Arrest ◽

A Cell ◽

Allelism Tests ◽

Complementation Groups

Abstract In Saccharomyces cerevisiae, the Swi6 protein is a component of two transcription factors, SBF and MBF, that promote expression of a large group of genes in the late G1 phase of the cell cycle. Although SBF is required for cell viability, SWI6 is not an essential gene. We performed a synthetic lethal screen to identify genes required for viability in the absence of SWI6 and identified 10 complementation groups of swi6-dependent lethal mutants, designated SLM1 through SLM10. We were most interested in mutants showing a cell cycle arrest phenotype; both slm7-1 swi6Δ and slm8-1 swi6Δ double mutants accumulated as large, unbudded cells with increased 1N DNA content and showed a temperature-sensitive growth arrest in the presence of Swi6. Analysis of the transcript levels of cell cycle-regulated genes in slm7-1 SWI6 mutant strains at the permissive temperature revealed defects in regulation of a subset of cyclin-encoding genes. Complementation and allelism tests showed that SLM7 is allelic with the TAF17 gene, which encodes a histone-like component of the general transcription factor TFIID and the SAGA histone acetyltransferase complex. Sequencing showed that the slm7-1 allele of TAF17 is predicted to encode a version of Taf17 that is truncated within a highly conserved region. The cell cycle and transcriptional defects caused by taf17slm7-1 are consistent with the role of TAFIIs as modulators of transcriptional activation and may reflect a role for TAF17 in regulating activation by SBF and MBF.

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A Screen for Genes Involved in the Anaphase Proteolytic Pathway Identifies tsm1+, a Novel Schizosaccharomyces pombe Gene Important for Microtubule Integrity

Genetics ◽

10.1093/genetics/149.3.1251 ◽

1998 ◽

Vol 149 (3) ◽

pp. 1251-1264

Author(s):

Ekaterina L Grishchuk ◽

James L Howe ◽

J Richard McIntosh

Keyword(s):

Schizosaccharomyces Pombe ◽

Nuclear Division ◽

Mitotic Division ◽

Temperature Sensitive ◽

Permissive Temperature ◽

Anaphase Promoting Complex ◽

Chloromethyl Ketone ◽

Proteolytic Pathway ◽

Functional Involvement ◽

Spindle Elongation

Abstract The growth of several mitotic mutants of Schizosaccharomyces pombe, including nuc2-663, is inhibited by the protease inhibitor N-Tosyl-L-Phenylalanine Chloromethyl Ketone (TPCK). Because nuc2+ encodes a presumptive component of the Anaphase Promoting Complex, which is required for the ubiquitin-dependent proteolysis of certain proteins during exit from mitosis, we have used sensitivity to TPCK as a criterion by which to search for novel S. pombe mutants defective in the anaphase-promoting pathway. In a genetic screen for temperature-sensitive mitotic mutants that were also sensitive to TPCK at a permissive temperature, we isolated three tsm (TPCK-sensitive mitotic) strains. Two of these are alleles of cut1+, but tsm1-512 maps to a novel genetic location. The tsm1-512 mutation leads to delayed nuclear division at restrictive temperatures, apparently as a result of an impaired ability to form a metaphase spindle. After shift of early G2 cells to 36°, tsm1-512 arrests transiently in the second mitotic division and then exits mitosis, as judged by spindle elongation and septation. The chromosomes, however, often fail to segregate properly. Genetic interactions between tsm1-512 and components of the anaphase proteolytic pathway suggest a functional involvement of the Tsm1 protein in this pathway.

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Actin and Microtubules Differently Contribute to Vacuolar Targeting Specificity during the Export from the ER

Membranes ◽

10.3390/membranes11040299 ◽

2021 ◽

Vol 11 (4) ◽

pp. 299

Author(s):

Monica De Caroli ◽

Fabrizio Barozzi ◽

Luciana Renna ◽

Gabriella Piro ◽

Gian-Pietro Di Sansebastiano

Keyword(s):

Spatial Targeting ◽

Traffic Regulation ◽

Emergent Features ◽

Vacuolar Sorting ◽

Er Export ◽

Golgi Network ◽

Relationship Of ◽

The Relationship ◽

Fine Tune

Plants rely on both actin and microtubule cytoskeletons to fine-tune sorting and spatial targeting of membranes during cell growth and stress adaptation. Considerable advances have been made in recent years in the comprehension of the relationship between the trans-Golgi network/early endosome (TGN/EE) and cytoskeletons, but studies have mainly focused on the transport to and from the plasma membrane. We address here the relationship of the cytoskeleton with different endoplasmic reticulum (ER) export mechanisms toward vacuoles. These emergent features of the plant endomembrane traffic are explored with an in vivo approach, providing clues on the traffic regulation at different levels beyond known proteins’ functions and interactions. We show how traffic of vacuolar markers, characterized by different vacuolar sorting determinants, diverges at the export from the ER, clearly involving different components of the cytoskeleton.

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Phenotype–genotype relationships in peroxisome biogenesis disorders of PEX1-defective complementation group 1 are defined by Pex1p–Pex6p interaction

Biochemical Journal ◽

10.1042/bj3570417 ◽

2001 ◽

Vol 357 (2) ◽

pp. 417-426 ◽

Cited By ~ 1

Author(s):

Shigehiko TAMURA ◽

Naomi MATSUMOTO ◽

Atsushi IMAMURA ◽

Nobuyuki SHIMOZAWA ◽

Yasuyuki SUZUKI ◽

...

Keyword(s):

Zellweger Syndrome ◽

Complementation Group ◽

Temperature Sensitive ◽

Permissive Temperature ◽

Peroxisome Biogenesis ◽

Causative Gene ◽

Aaa Atpase ◽

Peroxisome Biogenesis Disorders ◽

The Stability

The peroxisome biogenesis disorders (PBDs), including Zellweger syndrome (ZS), neonatal adrenoleucodystrophy (NALD) and infantile Refsum disease (IRD), are fatal autosomal recessive diseases caused by impaired peroxisome biogenesis, of which 12 genotypes have been reported. ZS patients manifest the severest clinical and biochemical abnormalities, whereas those with NALD and IRD show less severity and the mildest features respectively. We have reported previously that temperature-sensitive peroxisome assembly is responsible for the mildness of the clinical features of IRD. PEX1 is the causative gene for PBDs of complementation group E (CG-E, CG1 in the U.S.A. and Europe), the PBDs of highest incidence, encoding the peroxin Pex1p of the AAA ATPase family. It has been also reported that Pex1p and Pex6p interact with each other. In the present study we investigated phenotype–genotype relationships of CG1 PBDs. Pex1p from IRD such as Pex1p with the most frequently identified mutation at G843D was largely degraded in vivo at 37°C, whereas a normal level of Pex1p was detectable at the permissive temperature. In contrast, PEX1 proteins derived from ZS patients, including proteins with a mutation at L664P or the deletion of residues 634–690, were stably present at both temperatures. Pex1p-G843D interacted with Pex6p at approx. 50% of the level of normal Pex1p, whereas Pex1p from ZS patients mostly showing non-temperature-sensitive peroxisome biogenesis hardly bound to Pex6p. Taking these results together, we consider it most likely that the stability of Pex1p reflects temperature-sensitive peroxisome assembly in IRD fibroblasts. Failure in Pex1p–Pex6p interaction gives rise to more severe abnormalities, such as those manifested by patients with ZS.

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Identification of temperature-sensitive DNA- mutants of Chinese hamster cells affected in cellular and viral DNA synthesis

Molecular and Cellular Biology ◽

10.1128/mcb.6.12.4594-4601.1986 ◽

1986 ◽

Vol 6 (12) ◽

pp. 4594-4601

Author(s):

J J Dermody ◽

B E Wojcik ◽

H Du ◽

H L Ozer

Keyword(s):

Dna Replication ◽

Dna Synthesis ◽

Chinese Hamster ◽

Human Adenovirus ◽

Temperature Sensitive ◽

Restrictive Temperature ◽

Permissive Temperature ◽

Dependent Manner ◽

Viral Dna ◽

Cell Functions

We described a strategy which facilitates the identification of cell mutants which are restricted in DNA synthesis in a temperature-dependent manner. A collection of over 200 cell mutants temperature-sensitive for growth was isolated in established Chinese hamster cell lines (CHO and V79) by a variety of selective and nonselective techniques. Approximately 10% of these mutants were identified as ts DNA- based on differential inhibition of macromolecular synthesis at the restrictive temperature (39 degrees C) as assessed by incorporation of [3H]thymidine and [35S]methionine. Nine such mutants, selected for further study, demonstrated rapid shutoff of DNA replication at 39 degrees C. Infections with two classes of DNA viruses extensively dependent on host-cell functions for their replication were used to distinguish defects in DNA synthesis itself from those predominantly affecting other aspects of DNA replication. All cell mutants supported human adenovirus type 2 (Ad2) and mouse polyomavirus DNA synthesis at the permissive temperature. Five of the nine mutants (JB3-B, JB3-O, JB7-K, JB8-D, and JB11-J) restricted polyomavirus DNA replication upon transfection with viral sequences at 33 degrees C and subsequent shift to 39 degrees C either before or after the onset of viral DNA synthesis. Only one of these mutants (JB3-B) also restricted Ad2 DNA synthesis after virion infection under comparable conditions. No mutant was both restrictive for Ad2 and permissive for polyomavirus DNA synthesis at 39 degrees C. The differential effect of these cell mutants on viral DNA synthesis is expected to assist subsequent definition of the biochemical defect responsible.

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Isolation of a Schizosaccharomyces pombe rad21ts Mutant That Is Aberrant in Chromosome Segregation, Microtubule Function, DNA Repair and Sensitive to Hydroxyurea: Possible Involvement of Rad21 in Ubiquitin-Mediated Proteolysis

Genetics ◽

10.1093/genetics/148.1.49 ◽

1998 ◽

Vol 148 (1) ◽

pp. 49-57

Author(s):

Kazuo Tatebayashi ◽

Jun-ichi Kato ◽

Hideo Ikeda

Keyword(s):

Dna Repair ◽

Temperature Sensitive ◽

Permissive Temperature ◽

Repair Gene ◽

Tubulin Genes ◽

Gene Coding ◽

Abnormal Mitosis ◽

Dna Repair Gene ◽

Nuclear Structures ◽

Microtubule Function

Abstract The fission yeast DNA repair gene rad21+ is essential for cell growth. To investigate the function essential for cell proliferation, we have isolated a temperature-sensitive mutant of the rad21+ gene. The mutant, rad21-K1, showed abnormal mitosis at the nonpermissive temperature. Some cells contained abnormal nuclear structures, such as condensed chromosomes with short spindles, or chromosomes stretched or unequally separated by elongating spindles. Other cells exhibited the displaced nucleus or a cut-like phenotype. Similar abnormalities were observed when the Rad21 protein was depleted from cells. We therefore concluded that Rad21 is essential for proper segregation of chromosomes. Moreover, the rad21-K1 mutant is sensitive not only to UV and γ-ray irradiation but to thiabendazole and hydroxyurea, indicating that Rad21 plays important roles in microtubule function, DNA repair, and S phase function. The relation to the microtubule function was further confirmed by the fact that rad21+ genetically interacts with tubulin genes, nda2+ and nda3+. Finally, the growth of the rad21-K1 mutant was inhibited at the permissive temperature by introduction of another mutation in the cut9+ gene, coding for a component of the 20S cyclosome/anaphase promoting complex, which is involved in ubiquitin-mediated proteolysis. The results suggest that these diverse functions of Rad21 may be facilitated through ubiquitin-mediated proteolysis.

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DBF8, an essential gene required for efficient chromosome segregation in Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.14.9.6350-6360.1994 ◽

1994 ◽

Vol 14 (9) ◽

pp. 6350-6360

Author(s):

F Houman ◽

C Holm

Keyword(s):

Saccharomyces Cerevisiae ◽

Chromosome Segregation ◽

Mutational Analysis ◽

Essential Gene ◽

Chromosome Loss ◽

Temperature Sensitive ◽

Restrictive Temperature ◽

Permissive Temperature ◽

Nonsense Mutations ◽

Carboxy Terminal

To investigate chromosome segregation in Saccharomyces cerevisiae, we examined a collection of temperature-sensitive mutants that arrest as large-budded cells at restrictive temperatures (L. H. Johnston and A. P. Thomas, Mol. Gen. Genet. 186:439-444, 1982). We characterized dbf8, a mutation that causes cells to arrest with a 2c DNA content and a short spindle. DBF8 maps to chromosome IX near the centromere, and it encodes a 36-kDa protein that is essential for viability at all temperatures. Mutational analysis reveals that three dbf8 alleles are nonsense mutations affecting the carboxy-terminal third of the encoded protein. Since all of these mutations confer temperature sensitivity, it appears that the carboxyl-terminal third of the protein is essential only at a restrictive temperature. In support of this conclusion, an insertion of URA3 at the same position also confers a temperature-sensitive phenotype. Although they show no evidence of DNA damage, dbf8 mutants exhibit increased rates of chromosome loss and nondisjunction even at a permissive temperature. Taken together, our data suggest that Dbf8p plays an essential role in chromosome segregation.

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Growth Properties of Neural Cell Lines Immortalized with the Tsa58 Allele of Sv40 Large T Antigen

Cell Transplantation ◽

10.1177/096368979700600306 ◽

1997 ◽

Vol 6 (3) ◽

pp. 231-238 ◽

Cited By ~ 5

Author(s):

M.E. Truckenmiller ◽

Ora Dillon-Carter ◽

Carlo Tornatore ◽

Henrietta Kulaga ◽

Hidetoshi Takashima ◽

...

Keyword(s):

Amino Acid ◽

Cell Line ◽

Cell Lines ◽

T Antigen ◽

Temperature Sensitive ◽

Permissive Temperature ◽

Large T Antigen ◽

Wild Type ◽

Sv40 Large T Antigen ◽

Growth Properties

In vitro growth properties of three CNS-derived cell lines were compared under a variety of culture conditions. The M213-20 and J30a cell lines were each derived from embryonic CNS culture with the temperature-sensitive (ts) allele of SV40 large T antigen, tsA58, while the A7 cell line was immortalized using wild-type SV40 large T antigen. Cells immortalized with tsA58 SV40 large T proliferate at the permissive temperature, 33° C, while growth is expected to be suppressed at the nonpermissive temperature, 39.5°C. Both the M213-20 and J30a cell lines were capable of proliferating at 39.5°C continuously for up to 6 mo. All three cell lines showed no appreciable differences in growth rates related to temperature over a 7-day period in either serum-containing or defined serum-free media. The percentage of cells in S-phase of the cell cycle did not decrease or was elevated at 39.5°C for all three cell lines. After 3 wk at 39.5°C, the three cell lines also showed positive immunostaining using two monoclonal antibodies reacting with different epitopes of SV40 large T antigen. Double strand DNA sequence analyses of a 300 base pair (bp) fragment of the large T gene from each cell line, which included the ts locus, revealed mutations in both the J30a and M213-20 cell lines. The J30a cell line ts mutation had reverted to wild type, and two additional loci with bp substitutions with predicted amino acid changes were also found. While the ts mutation of the M213-20 cells was retained, an additional bp substitution with a predicted amino acid change was found. The A7 cell line sequence was identical to the reference wild-type sequence. These findings suggest that (a) nucleic acid sequences in the temperature-sensitive region of the tsA58 allele of SV40 large T are not necessarily stable, and (b) temperature sensitivity of cell lines immortalized with tsA58 is not necessarily retained.

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