scholarly journals Spatial self-organization favors heterotypic cooperation over cheating

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Babak Momeni ◽  
Adam James Waite ◽  
Wenying Shou
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Open Space ◽  
Partner Choice ◽  
Self Organization ◽  
Spatial Distributions ◽  
Fitness Effects ◽  
Spatial Environment ◽  
Engineered Saccharomyces Cerevisiae ◽  
Two Populations

Heterotypic cooperation—two populations exchanging distinct benefits that are costly to produce—is widespread. Cheaters, exploiting benefits while evading contribution, can undermine cooperation. Two mechanisms can stabilize heterotypic cooperation. In ‘partner choice’, cooperators recognize and choose cooperating over cheating partners; in ‘partner fidelity feedback’, fitness-feedback from repeated interactions ensures that aiding your partner helps yourself. How might a spatial environment, which facilitates repeated interactions, promote fitness-feedback? We examined this process through mathematical models and engineered Saccharomyces cerevisiae strains incapable of recognition. Here, cooperators and their heterotypic cooperative partners (partners) exchanged distinct essential metabolites. Cheaters exploited partner-produced metabolites without reciprocating, and were competitively superior to cooperators. Despite initially random spatial distributions, cooperators gained more partner neighbors than cheaters did. The less a cheater contributed, the more it was excluded and disfavored. This self-organization, driven by asymmetric fitness effects of cooperators and cheaters on partners during cell growth into open space, achieves assortment.

Improvement of Amorpha-4,11-diene Production by a Yeast-Conform Variant of Vitreoscilla Hemoglobin

2012 ◽  
Vol 67 (3-4) ◽  
pp. 195-207 ◽  
Author(s):  
Junhao Shen ◽  
Haina Zheng ◽  
Xiaohui Zhi ◽  
Yanwei Shi ◽  
Yong Huang ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Western Blot ◽  
Difference Spectrum ◽  
Vitreoscilla Hemoglobin ◽  
Expression Vectors ◽  
Chain Reactions ◽  
Polymerase Chain Reactions ◽  
Polymerase Chain ◽  
Engineered Saccharomyces Cerevisiae

Amorpha-4,11-diene is the precursor of the antimalarial compound artemisinin. The effect of Vitreoscilla hemoglobin (VHb) and its yeast-conform variant (VHbm) on amorpha-4,11- diene production in engineered Saccharomyces cerevisiae was investigated. First, the VHb gene was mutated to the yeast-conform variant VHbm based on step-by-step extension of a short region of the gene through a series of polymerase chain reactions (PCR). The artificial VHbm gene contained codons preferred by the yeast translation machinery. Two yeast expression vectors containing VHb or VHbm gene were constructed and introduced into the amorpha-4,11-diene-producing strain S. cerevisiae WK1 to form WK1[VHb] and WK1[VHbm], respectively. Western blot and CO-difference spectrum absorbance assay showed that VHb and VHbm were successfully expressed. In shake fl asks, VHbm expression conferred higher cell growth than VHb expression. GC-MS results indicated the amorpha- 4,11-diene production in WK1[VHbm] and WK1[VHb] was 3- and 2-fold higher than that in WK1, respectively. This suggests that VHb might improve the amorpha-4,11-diene production in engineered S. cerevisiae

scholarly journals The rye Mutants Identify a Role for Ssn/Srb Proteins of the RNA Polymerase II Holoenzyme During Stationary Phase Entry in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Ya-Wen Chang ◽  
Susie C Howard ◽  
Yelena V Budovskaya ◽  
Jasper Rine ◽  
Paul K Herman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Rna Polymerase ◽  
Stationary Phase ◽  
Yeast Cell ◽  
Rna Polymerase Ii ◽  
Transcriptional Response ◽  
Nutrient Deprivation ◽  
Ras Signaling ◽  
Rna Polymerase Ii Holoenzyme

Abstract Saccharomyces cerevisiae cells enter into a distinct resting state, known as stationary phase, in response to specific types of nutrient deprivation. We have identified a collection of mutants that exhibited a defective transcriptional response to nutrient limitation and failed to enter into a normal stationary phase. These rye mutants were isolated on the basis of defects in the regulation of YGP1 expression. In wild-type cells, YGP1 levels increased during the growth arrest caused by nutrient deprivation or inactivation of the Ras signaling pathway. In contrast, the levels of YGP1 and related genes were significantly elevated in the rye mutants during log phase growth. The rye defects were not specific to this YGP1 response as these mutants also exhibited multiple defects in stationary phase properties, including an inability to survive periods of prolonged starvation. These data indicated that the RYE genes might encode important regulators of yeast cell growth. Interestingly, three of the RYE genes encoded the Ssn/Srb proteins, Srb9p, Srb10p, and Srb11p, which are associated with the RNA polymerase II holoenzyme. Thus, the RNA polymerase II holoenzyme may be a target of the signaling pathways responsible for coordinating yeast cell growth with nutrient availability.

scholarly journals The Ras/PKA Signaling Pathway May Control RNA Polymerase II Elongation via the Spt4p/Spt5p Complex in Saccharomyces cerevisiae

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1059-1070
Author(s):  
Susie C Howard ◽  
Arelis Hester ◽  
Paul K Herman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Signaling Pathway ◽  
Elongation Factor ◽  
Ras Signaling ◽  
Elongation Step ◽  
Rna Polymerase Ii Transcription

Abstract The Ras signaling pathway in Saccharomyces cerevisiae controls cell growth via the cAMP-dependent protein kinase, PKA. Recent work has indicated that these effects on growth are due, in part, to the regulation of activities associated with the C-terminal domain (CTD) of the largest subunit of RNA polymerase II. However, the precise target of these Ras effects has remained unknown. This study suggests that Ras/PKA activity regulates the elongation step of the RNA polymerase II transcription process. Several lines of evidence indicate that Spt5p in the Spt4p/Spt5p elongation factor is the likely target of this control. First, the growth of spt4 and spt5 mutants was found to be very sensitive to changes in Ras/PKA signaling activity. Second, mutants with elevated levels of Ras activity shared a number of specific phenotypes with spt5 mutants and vice versa. Finally, Spt5p was efficiently phosphorylated by PKA in vitro. Altogether, the data suggest that the Ras/PKA pathway might be directly targeting a component of the elongating polymerase complex and that this regulation is important for the normal control of yeast cell growth. These data point out the interesting possibility that signal transduction pathways might directly influence the elongation step of RNA polymerase II transcription.

scholarly journals Prohibitins Regulate Membrane Protein Degradation by the m-AAA Protease in Mitochondria

1999 ◽  
Vol 19 (5) ◽  
pp. 3435-3442 ◽  
Author(s):  
Gregor Steglich ◽  
Walter Neupert ◽  
Thomas Langer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Membrane Proteins ◽  
Eukaryotic Cells ◽  
Mitochondrial Morphology ◽  
Regulatory Effect ◽  
Inner Membrane ◽  
Functional Activities ◽  
Native Molecular Mass ◽  
Affect Cell Growth

ABSTRACT Prohibitins comprise a protein family in eukaryotic cells with potential roles in senescence and tumor suppression. Phb1p and Phb2p, members of the prohibitin family in Saccharomyces cerevisiae, have been implicated in the regulation of the replicative life span of the cells and in the maintenance of mitochondrial morphology. The functional activities of these proteins, however, have not been elucidated. We demonstrate here that prohibitins regulate the turnover of membrane proteins by the m-AAA protease, a conserved ATP-dependent protease in the inner membrane of mitochondria. The m-AAA protease is composed of the homologous subunits Yta10p (Afg3p) and Yta12p (Rca1p). Deletion ofPHB1 or PHB2 impairs growth of Δyta10 or Δyta12 cells but does not affect cell growth in the presence of the m-AAA protease. A prohibitin complex with a native molecular mass of approximately 2 MDa containing Phb1p and Phb2p forms a supercomplex with them-AAA protease. Proteolysis of nonassembled inner membrane proteins by the m-AAA protease is accelerated in mitochondria lacking Phb1p or Phb2p, indicating a negative regulatory effect of prohibitins on m-AAA protease activity. These results functionally link members of two conserved protein families in eukaryotes to the degradation of membrane proteins in mitochondria.

Production of (–)-α-bisabolol in metabolically engineered Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Tae Yeob Kim ◽  
Haeseong Park ◽  
Sun-Ki Kim ◽  
Soo-Jung Kim ◽  
Yong-Cheol Park
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Engineered Saccharomyces Cerevisiae
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