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A Glutamine/Asparagine-Rich Fragment of Gln3, but not the Full-Length Protein, Aggregates in Saccharomyces cerevisiae

K. S. Antonets1,2, H. M. Sargsyan1, and A. A. Nizhnikov1,2,3*

1St. Petersburg State University, Department of Genetics and Biotechnology, 199034 St. Petersburg, Russia; E-mail: ant.nizhnikov@gmail.com

2Vavilov Institute of General Genetics, St. Petersburg Branch, Russian Academy of Sciences, 199034 St. Petersburg, Russia

3All-Russia Research Institute for Agricultural Microbiology, 196608 Pushkin, St. Petersburg, Russia

* To whom correspondence should be addressed.

Received October 14, 2015; Revision received December 16, 2015
The amino acid sequence of protein Gln3 in yeast Saccharomyces cerevisiae has a region enriched with Gln (Q) and Asn (N) residues. In this study, we analyzed the effects of overexpression of Gln3 and its Q/N-rich fragment fused with yellow fluorescent protein (YFP). Being overexpressed, full-length Gln3-YFP does not form aggregates, inhibits vegetative growth, and demonstrates nuclear localization, while the Q/N-rich fragment (Gln3QN) fused with YFP forms aggregates that do not colocalize with the nucleus and do not affect growth of the cells. Although detergent-resistant aggregates of Gln3QN are formed in the absence of yeast prions, the aggregation of Gln3QN significantly increases in the presence of [PIN+] prion, while in the presence of two prions, [PSI+] and [PIN+], the percentage of cells with Gln3QN aggregates is significantly lower than in the strain bearing only [PIN+]. Data on colocalization demonstrate that this effect is mediated by interaction between Gln3QN aggregates and [PSI+] and [PIN+] prions.
KEY WORDS: amyloid, prion, Gln3, Rnq1, Sup35, yeast, S. cerevisiae

DOI: 10.1134/S0006297916040118