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[ PSI + ] aggregate enlargement in rnq1 nonprion domain mutants, leading to a loss of prion in yeast
Author(s) -
Kurahashi Hiroshi,
Pack ChanGi,
Shibata Shoichiro,
Oishi Keita,
Sako Yasushi,
Nakamura Yoshikazu
Publication year - 2011
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2011.01511.x
Subject(s) - biology , yeast , mutant , domain (mathematical analysis) , aggregate (composite) , resizing , microbiology and biotechnology , genetics , gene , nanotechnology , mathematical analysis , materials science , mathematics , european union , economic policy , business
[ PIN + ] is the prion form of the Rnq1 protein of unknown function in Saccharomyces cerevisiae . A glutamine/asparagine (Q/N)‐rich C‐terminal domain is necessary for the propagation of [ PIN + ], whereas the N‐terminal region is non‐Q/N‐rich and considered the nonprion domain. Here, we isolated numerous single‐amino‐acid mutations in Rnq1, phenotypically similar to Rnq1Δ100, which inhibit [ PSI + ] propagation in the [ PIN + ] state, but not in the [ pin − ] state, when overproduced. The dynamics of the prion aggregates was analyzed by semi‐denaturing detergent‐agarose gel electrophoresis and fluorescence correlation spectroscopy. The results indicated that [ PSI + ] aggregates were enlarged in mother cells and, instead, not apparently transmitted into daughter cells. Under these conditions, the activity of Hsp104, a known prion disaggregase, was not affected when monitored for the thermotolerance of the rnq1 mutants. These [ PSI + ]‐inhibitory rnq1 mutations did not affect [ PIN + ] propagation itself when over‐expressed from a strong promoter, but instead destabilized [ PIN + ] when expressed from the weak authentic RNQ1 promoter. The majority of these mutated residues are mapped to the surface, and on one side, of contiguous α‐helices of the nonprion domain of Rnq1, suggesting its involvement in interactions with a prion or a factor necessary for prion development.