TY - JOUR
T1 - The relationship between visible intracellular aggregates that appear after overexpression of Sup35 and the yeast prion-like elements [PSI+] and [PIN+]
AU - Zhou, Ping
AU - Derkatch, Irina L.
AU - Liebman, Susan W.
PY - 2001/1/30
Y1 - 2001/1/30
N2 - Overproduced fusions of Sup35 or its prion domain with green fluorescent protein (GFP) have previously been shown to form frequent dots in [PSI+] cells. Rare foci seen in [psi-] cells were hypothesized to indicate the de novo induction of [PSI+] caused by the overproduced prion domain. Here, we describe novel ring-type aggregates that also appear in [psi-] cultures upon Sup35 overproduction and show directly that dot and ring aggregates only appear in cells that have become [PSI+]. The formation of either type of aggregate requires [PIN+], an element needed for the induction of [PSI+]. Although aggregates are visible predominantly in stationary-phase cultures, [PSI+] induction starts in exponential phase, suggesting that much smaller aggregates can also propagate [PSI+]. Such small aggregates are probably present in [PSI+] cells and, upon Sup35-GFP overproduction, facilitate the frequent formation of dot aggregates, but only the occasional appearance of ring aggregates. In contrast, rings are very frequent when [PSI+] cultures, including those lacking [PIN+], are grown in the presence of GuHCl or excess Hsp104 while overexpressing Sup35-GFP. Thus, intermediates formed during [PSI+] curing seem to facilitate ring formation. Surprisingly, GuHCl and excess Hsp104, which are known to promote loss of [PSI+], did not prevent the de novo induction of [PSI+] by excess Sup35 in [psi-][PIN+] strains.
AB - Overproduced fusions of Sup35 or its prion domain with green fluorescent protein (GFP) have previously been shown to form frequent dots in [PSI+] cells. Rare foci seen in [psi-] cells were hypothesized to indicate the de novo induction of [PSI+] caused by the overproduced prion domain. Here, we describe novel ring-type aggregates that also appear in [psi-] cultures upon Sup35 overproduction and show directly that dot and ring aggregates only appear in cells that have become [PSI+]. The formation of either type of aggregate requires [PIN+], an element needed for the induction of [PSI+]. Although aggregates are visible predominantly in stationary-phase cultures, [PSI+] induction starts in exponential phase, suggesting that much smaller aggregates can also propagate [PSI+]. Such small aggregates are probably present in [PSI+] cells and, upon Sup35-GFP overproduction, facilitate the frequent formation of dot aggregates, but only the occasional appearance of ring aggregates. In contrast, rings are very frequent when [PSI+] cultures, including those lacking [PIN+], are grown in the presence of GuHCl or excess Hsp104 while overexpressing Sup35-GFP. Thus, intermediates formed during [PSI+] curing seem to facilitate ring formation. Surprisingly, GuHCl and excess Hsp104, which are known to promote loss of [PSI+], did not prevent the de novo induction of [PSI+] by excess Sup35 in [psi-][PIN+] strains.
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U2 - 10.1046/j.1365-2958.2001.02224.x
DO - 10.1046/j.1365-2958.2001.02224.x
M3 - Article
C2 - 11123686
AN - SCOPUS:0035179616
VL - 39
SP - 37
EP - 46
JO - Molecular Microbiology
JF - Molecular Microbiology
SN - 0950-382X
IS - 1
ER -