Mutants of Saccharomyces cerevisiae with defective vacuolar function

Kitamoto, Katsuhiko; Yoshizawa, Kiyoshi; Ohsumi, Yoshinori; Anraku, Yasuhiro

doi:10.1128/jb.170.6.2687-2691.1988

Cited by 79 publications

(60 citation statements)

References 19 publications

(11 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A third possibility is a change in vacuolar membrane function. In yeast, the vacuole serves as a Ca2+ sink and buffer for cytoplasmic Ca2+ homeostasis (Eilam et al, 1985;Kitamoto et al, 1988). An alteration in this buffer system could account for the Ca2+-sensitive properties of strain R4-3G.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of action of the phytotoxin syringomycin: a resistant mutant of Saccharomyces cerevisiae reveals an involvement of Ca2+ transport

Takemoto

Zhang

Taguchi

et al. 1991

Journal of General Microbiology

View full text Add to dashboard Cite

The bacterial phytotoxin syringomycin affects plasma-membrane-associated functions of plants and yeast. These include increases in transmembrane K+, H+ and Ca2+ fluxes and membrane potential. Mutants of Saccharomyces cerevisiae resistant to growth inhibition by syringomycin were isolated and characterized. Many of the mutant isolates were unable to grow in yeast extract/peptone/dextrose medium supplemented with 400 mM-CaC1, which permitted the growth of the parent strain (8A-1B). Genetic analyses of one of these mutants, strain R4-3G, showed a single recessive mutation that simultaneously led to Ca2+-sensitivity and syringomycin-resistance. R4-3G had higher net 45Ca2+ uptake rates than strain 8A-1B and higher intracellular Ca2+ levels in medium containing 1 mMCaCl,. The,aJtered 45Ca2+ uptake rates of the mutant were not influenced by syringomycin and were not related to altered capabilities for Ca2+ efflux. R4-3G had similar syringomycin-stimulated increases in K+ efflux but lower syringomycin-stimulated increases in membrane potential than 8A-1B. It is concluded that Ca2+ transport is important in the response of yeast to syringomycin and that the toxin-stimulated membrane potential increase, but not K+ efflux, is closely associated with Ca2+ transport.

show abstract

Section: Discussionmentioning

confidence: 99%

Mechanism of action of the phytotoxin syringomycin: a resistant mutant of Saccharomyces cerevisiae reveals an involvement of Ca2+ transport

Takemoto

Zhang

Taguchi

et al. 1991

Journal of General Microbiology

View full text Add to dashboard Cite

show abstract

“…The HOPS complex controls membrane fusion with the vacuole, and thus mutation of HOPS components results in highly fragmented vacuoles (Banta et al 1988;Kitamoto et al 1988b;Raymond et al 1992). Given that the vacuolar membrane serves as a platform for TORC1 activity, vacuolar fragmentation caused by vps-c mutations may destabilize TORC1 and thus affect EGOC-TORC1 interactions.…”

Section: Vps-c Complex Functions Upstream Of Torc1mentioning

confidence: 99%

“…However, EGOC is not the sole conduit by which the Vps-C complex regulates TORC1, and there are additional inputs. Previous studies, including our own, have shown that vps-c mutants have low amino acid concentrations (Kitamoto et al 1988b;Zurita-Martinez et al 2007). Because the Vps-C complex contributes to elicit TORC1 activity via the amino acidresponsive EGOC, this regulation may be effected through its role in maintaining amino acid homeostasis.…”

mentioning

confidence: 99%

“…Both the HOPS and the CORVET complexes are highly conserved from yeasts to metazoans (reviewed in Nickerson et al 2009). The vps-c mutants display highly fragmented vacuoles, which are the major amino acid storage reservoir in yeast, and show reduced levels of amino acids (Banta et al 1988;Kitamoto et al 1988b;Raymond et al 1992). The vps-c mutants display severe rapamycin sensitivity and recovery defects and fail to recover from starvation-imposed arrest (ZuritaMartinez et al 2007).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Endolysosomal Membrane Trafficking Complexes Drive Nutrient-Dependent TORC1 Signaling to Control Cell Growth in Saccharomyces cerevisiae

et al. 2014

View full text Add to dashboard Cite

The rapamycin-sensitive and endomembrane-associated TORC1 pathway controls cell growth in response to nutrients in eukaryotes. Mutations in class C Vps (Vps-C) complexes are synthetically lethal with tor1 mutations and confer rapamycin hypersensitivity in Saccharomyces cerevisiae, suggesting a role for these complexes in TORC1 signaling. Vps-C complexes are required for vesicular trafficking and fusion and comprise four distinct complexes: HOPS and CORVET and their minor intermediaries (i)-CORVET and i-HOPS. We show that at least one Vps-C complex is required to promote TORC1 activity, with the HOPS complex having the greatest input. The vps-c mutants fail to recover from rapamycin-induced growth arrest and show low levels of TORC1 activity. TORC1 promotes cell growth via Sch9, a p70 S6 kinase ortholog. Constitutively active SCH9 or hyperactive TOR1 alleles restored rapamycin recovery and TORC1 activity of vps-c mutants, supporting a role for the Vps-C complexes upstream of TORC1. The EGO GTPase complex Exit from G 0 Complex (EGOC) and its homologous Rag-GTPase complex convey amino acid signals to TORC1 in yeast and mammals, respectively. Expression of the activated EGOC GTPase subunits Gtr1 GTP and Gtr2 GDP partially suppressed vps-c mutant rapamycin recovery defects, and this suppression was enhanced by increased amino acid concentrations. Moreover, vps-c mutations disrupted EGOC-TORC1 interactions. TORC1 defects were more severe for vps-c mutants than those observed in EGOC mutants. Taken together, our results support a model in which distinct endolysosomal trafficking Vps-C complexes promote rapamycin-sensitive TORC1 activity via multiple inputs, one of which involves maintenance of amino acid homeostasis that is sensed and transmitted to TORC1 via interactions with EGOC.T HE Target of rapamycin (TOR) kinases are conserved across eukaryotes and orchestrate myriad cellular processes to control growth in response to nutrients and environmental signals. The Tor kinases form two evolutionarily conserved multi-protein complexes known as TORC1 (Tor complex) and TORC2. TORC1 is sensitive to the immunosuppressive and antiproliferative drug rapamycin, and in Saccharomyces cerevisiae is populated by Tor1 (or, to a lesser extent, Tor2), Kog1, Lst8, and Tco89. TORC1 controls cell growth when nutrients such as amino acids are abundant and serves to maintain robust nutrient transport, ribosome biogenesis, and protein synthesis and concomitantly inhibits autophagy (Heitman et al. 1991;Cardenas et al. 1999;Powers and Walter 1999;Loewith et al. 2002;Reinke et al. 2004;Wullschleger et al. 2006;Loewith and Hall 2011). TORC2 is rapamycin-insensitive and composed of Tor2, Lst8, Bit61/Bit2, Avo1, Avo2, and Avo3; TORC2 controls spatial growth via regulation of actin cytoskeleton polarization (Schmidt et al. 1996;Loewith et al. 2002). Amino acid levels are signaled to yeast TORC1, at least in part, via the leucyl-tRNA synthetase, which binds and influences the guanine nucleotide state of components of the Rag GTPase EGOC (...

show abstract

“…Substantial portions of the intracellular amino acids are compartmentalized within the cell, mainly in the vacuole. Redistribution of amino acids between compartments in response to metabolic signals has been demonstrated (Wiemken, 1980;Messenguy et al, 1980;Kitamoto et al, 1988). However, to what extent compartmentalization of metabolites may play a role in regulation of pathways other than in amino acid biosynthesis is as yet unknown and further research work along these lines is in progress.…”

mentioning

confidence: 99%

Glutathione as an endogenous sulphur source in the yeast Saccharomyces cerevisiae

Elskens

Jaspers

Penninckx

1991

Journal of General Microbiology

106

View full text Add to dashboard Cite

Glutathione-deficient mutants (@A) of the yeast Saccharomyces cerevisiae, impaired in the first step of glutathione (GSH) biosynthesis were studied with respect to the regulation of enzymes involved in GSH catabolism and cysteine biosynthesis. Striking differences were observed in the content of the sulphur amino acids when gshA mutants were compared to wild-type strains growing on the same minimal medium. Furthermore, all mutants examined showed a derepression of y-glutamyltranspeptidase (y-GT), the enzyme initiating GSH degradation. However, y-cystathionase and cysteine synthase were unaffected by the GSH deficiency as long as the nutrient sulphate source was not exhausted. The results suggest that the mutants are probably not impaired in the sulphate assimilation pathway, but that the y-glutamyl cycle could play a leading role in the regulation of the sulphur fluxes. Studies of enzyme regulation showed that the derepression of y-GT observed in thegshA strains was most probably due to an alteration of the thiol status. The effectors governing the biosynthesis of cysteine synthase and ycystathionase seemed different from those playing a role in y-GT regulation and it was only under conditions of total sulphate deprivation that all these enzymes were derepressed. As a consequence the endogenous pool of GSH was used in the synthesis of cysteine. GSH might, therefore, fulfil the role of a storage compound.

show abstract

Mutants of Saccharomyces cerevisiae with defective vacuolar function

Cited by 79 publications

References 19 publications

Mechanism of action of the phytotoxin syringomycin: a resistant mutant of Saccharomyces cerevisiae reveals an involvement of Ca2+ transport

Mechanism of action of the phytotoxin syringomycin: a resistant mutant of Saccharomyces cerevisiae reveals an involvement of Ca2+ transport

Endolysosomal Membrane Trafficking Complexes Drive Nutrient-Dependent TORC1 Signaling to Control Cell Growth in Saccharomyces cerevisiae

Glutathione as an endogenous sulphur source in the yeast Saccharomyces cerevisiae

Contact Info

Product

Resources

About