Stress-responsive Gln3 localization in Saccharomyces cerevisiae is separable from and can overwhelm nitrogen source regulation.
Intracellular localization of Saccharomyces cerevisiae GATA family transcription activator, Gln3, is used as a downstream readout of rapamycin-inhibited Tor1,2 control of Tap42 and Sit4 activities. Gln3 is cytoplasmic in cells provided with repressive nitrogen sources such as glutamine and is nuclear in cells growing with a derepressive nitrogen source such as proline or those treated with rapamycin or methionine sulfoximine (Msx). Although gross Gln3-Myc13 phosphorylation levels in wild type cells do not correlate with nitrogen source-determined intracellular Gln3-Myc13 localization, the phosphorylation levels are markedly influenced by several environmental perturbations. Msx treatment increases Snf1-independent Gln3-Myc13 phosphorylation, whereas carbon starvation increases both Snf1-dependent and -independent Gln3-Myc13 phosphorylation. Here we demonstrate that a broad spectrum of environmental stresses (temperature, osmotic, and oxidative) increase Gln3-Myc13 phosphorylation. In parallel, these stresses elicit rapid (<5 min for NaCl) Gln3-Myc13 relocalization from the nucleus to the cytoplasm. The response of Gln3-Myc13 localization to stressful conditions can completely overwhelm its response to nitrogen source quality or inhibitor-generated disruption of the Tor1,2 signal transduction pathway. Adding NaCl to cells cultured under conditions in which Gln3-Myc13 is normally nuclear, i.e. proline-grown, nitrogen-starved, Msx-, caffeine-, and rapamycin-treated wild type cells, or ure2Delta cells, results in its prompt relocalization to the cytoplasm. Together these data identify a major new level of regulation to which Gln3 responds, and adds a new dimension to mechanistic studies of the regulation of this transcription factor.
Tate
Jennifer J
JJ
Department of Molecular Sciences, University of Tennessee, Memphis, Tennessee 38163.
Cooper
Terrance G
TG
Department of Molecular Sciences, University of Tennessee, Memphis, Tennessee 38163. Electronic address: tcooper@utmem.edu.
D002244:Carbon / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005973:Glutamine / Q000378:metabolism; D008717:Methionine Sulfoximine / Q000378:metabolism; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010766:Phosphorylation; D011392:Proline / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism*
C071664:GLN3 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D005973:Glutamine; D008717:Methionine Sulfoximine; D012965:Sodium Chloride; D002244:Carbon; D011392:Proline; D009584:Nitrogen; D020123:Sirolimus