Faculty Opinions recommendation of Removal of a single alpha-tubulin gene intron suppresses cell cycle arrest phenotypes of splicing factor mutations in Saccharomyces cerevisiae.

2002 ◽  
Author(s):  
Thomas Blumenthal
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Splicing Factor ◽  
Tubulin Gene ◽  
Alpha Tubulin ◽  
Cycle Arrest

scholarly journals The ORC/Cdc6/MCM2-7 complex facilitates MCM2-7 dimerization during prereplicative complex formation

2013 ◽  
Vol 42 (4) ◽  
pp. 2257-2269 ◽  
Author(s):  
Cecile Evrin ◽  
Alejandra Fernández-Cid ◽  
Alberto Riera ◽  
Juergen Zech ◽  
Pippa Clarke ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Complex Formation ◽  
Cell Cycle Arrest ◽  
Atp Hydrolysis ◽  
Cycle Arrest ◽  
Helicase Loading ◽  
Limiting Step ◽  
Prereplicative Complex ◽  
Dominant Lethality

Abstract The replicative mini-chromosome-maintenance 2–7 (MCM2-7) helicase is loaded in Saccharomyces cerevisiae and other eukaryotes as a head-to-head double-hexamer around origin DNA. At first, ORC/Cdc6 recruits with the help of Cdt1 a single MCM2-7 hexamer to form an ‘initial’ ORC/Cdc6/Cdt1/MCM2-7 complex. Then, on ATP hydrolysis and Cdt1 release, the ‘initial’ complex is transformed into an ORC/Cdc6/MCM2-7 (OCM) complex. However, it remains unclear how the OCM is subsequently converted into a MCM2-7 double-hexamer. Through analysis of MCM2-7 hexamer-interface mutants we discovered a complex competent for MCM2-7 dimerization. We demonstrate that these MCM2-7 mutants arrest during prereplicative complex (pre-RC) assembly after OCM formation, but before MCM2-7 double-hexamer assembly. Remarkably, only the OCM complex, but not the ‘initial’ ORC/Cdc6/Cdt1/MCM2-7 complex, is competent for MCM2-7 dimerization. The MCM2-7 dimer, in contrast to the MCM2-7 double-hexamer, interacts with ORC/Cdc6 and is salt-sensitive, classifying the arrested complex as a helicase-loading intermediate. Accordingly, we found that overexpression of the mutants cause cell-cycle arrest and dominant lethality. Our work identifies the OCM complex as competent for MCM2-7 dimerization, reveals MCM2-7 dimerization as a limiting step during pre-RC formation and defines critical mechanisms that explain how origins are licensed.

scholarly journals Role of Cdc42-Cla4 Interaction in the Pheromone Response of Saccharomyces cerevisiae

2006 ◽  
Vol 6 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Melanie Heinrich ◽  
Tim Köhler ◽  
Hans-Ulrich Mösch
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Map Kinase ◽  
Cell Cycle Arrest ◽  
Map Kinases ◽  
Negative Regulator ◽  
Cycle Arrest ◽  
Mitogen Activated Protein ◽  
Novel Alleles

ABSTRACT In Saccharomyces cerevisiae, the highly conserved Rho-type GTPase Cdc42 is essential for cell division and controls cellular development during mating and invasive growth. The role of Cdc42 in mating has been controversial, but a number of previous studies suggest that the GTPase controls the mitogen-activated protein (MAP) kinase cascade by activating the p21-activated protein kinase (PAK) Ste20. To further explore the role of Cdc42 in pheromone-stimulated signaling, we isolated novel alleles of CDC42 that confer resistance to pheromone. We find that in CDC42(V36A) and CDC42(V36A, I182T) mutant strains, the inability to undergo pheromone-induced cell cycle arrest correlates with reduced phosphorylation of the mating MAP kinases Fus3 and Kss1 and with a decrease in mating efficiency. Furthermore, Cdc42(V36A) and Cdc42(V36A, I182T) proteins show reduced interaction with the PAK Cla4 but not with Ste20. We also show that deletion of CLA4 in a CDC42(V36A, I182T) mutant strain suppresses pheromone resistance and that overexpression of CLA4 interferes with pheromone-induced cell cycle arrest and MAP kinase phosphorylation in CDC42 wild-type strains. Our data indicate that Cla4 has the potential to act as a negative regulator of the mating pathway and that this function of the PAK might be under control of Cdc42. In conclusion, our study suggests that control of pheromone signaling by Cdc42 not only depends on Ste20 but also involves interaction of the GTPase with Cla4.

scholarly journals Human Immunodeficiency Virus Type 1 Vpr Induces G2 Checkpoint Activation by Interacting with the Splicing Factor SAP145

2006 ◽  
Vol 26 (21) ◽  
pp. 8149-8158 ◽  
Author(s):  
Yasuhiko Terada ◽  
Yuko Yasuda
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Cell Cycle Arrest ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Splicing Factor ◽  
Checkpoint Activation ◽  
Cycle Arrest ◽  
Immunodeficiency Virus

ABSTRACT Vpr, the viral protein R of human immunodeficiency virus type 1, induces G2 cell cycle arrest and apoptosis in mammalian cells via ATR (for “ataxia-telangiectasia-mediated and Rad3-related”) checkpoint activation. The expression of Vpr induces the formation of the γ-histone 2A variant X (H2AX) and breast cancer susceptibility protein 1 (BRCA1) nuclear foci, and a C-terminal domain is required for Vpr-induced ATR activation and its nuclear localization. However, the cellular target of Vpr, as well as the mechanism of G2 checkpoint activation, was unknown. Here we report that Vpr induces checkpoint activation and G2 arrest by binding to the CUS1 domain of SAP145 and interfering with the functions of the SAP145 and SAP49 proteins, two subunits of the multimeric splicing factor 3b (SF3b). Vpr interacts with and colocalizes with SAP145 through its C-terminal domain in a speckled distribution. The depletion of either SAP145 or SAP49 leads to checkpoint-mediated G2 cell cycle arrest through the induction of nuclear foci containing γ-H2AX and BRCA1. In addition, the expression of Vpr excludes SAP49 from the nuclear speckles and inhibits the formation of the SAP145-SAP49 complex. To conclude, these results point out the unexpected roles of the SAP145-SAP49 splicing factors in cell cycle progression and suggest that cellular expression of Vpr induces checkpoint activation and G2 arrest by interfering with the function of SAP145-SAP49 complex in host cells.

Differential transmission of G1 cell cycle arrest and mating signals by Saccharomyces cerevisiae Ste5 mutants in the pheromone pathway

1999 ◽  
Vol 77 (5) ◽  
pp. 459-468
Author(s):  
You-Jeong Choi ◽  
Sun-Hong Kim ◽  
Ki-Sook Park ◽  
Kang-Yell Choi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Signal Transduction ◽  
Cell Cycle Arrest ◽  
Mitogen Activated Protein Kinase ◽  
Chemical Mutagenesis ◽  
G1 Arrest ◽  
Cycle Arrest ◽  
Isolation And Characterization ◽  
G1 Cell Cycle Arrest

Saccharomyces cerevisiae Ste5 is a scaffold protein that recruits many pheromone signaling molecules to sequester the pheromone pathway from other homologous mitogen-activated protein kinase pathways. G1 cell cycle arrest and mating are two different physiological consequences of pheromone signal transduction and Ste5 is required for both processes. However, the roles of Ste5 in G1 arrest and mating are not fully understood. To understand the roles of Ste5 better, we isolated 150 G1 cell cycle arrest defective STE5 mutants by chemical mutagenesis of the gene. Here, we found that two G1 cell cycle arrest defective STE5 mutants (ste5MD248V and ste5delta-776) retained mating capacity. When overproduced in a wild-type strain, several ste5 mutants also showed different dominant phenotypes for G1 arrest and mating. Isolation and characterization of the mutants suggested separable roles of Ste5 in G1 arrest and mating of S. cerevisiae. In addition, the roles of Asp-248 and Tyr-421, which are important for pheromone signal transduction were further characterized by site-directed mutagenesis studies.Key words: Ste5, Saccharomyces cerevisiae, signal transduction, mating, G1 cell cycle arrest.

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