Open AccessDistinct Subregions of Swi1 Manifest Striking Differences in Prion Transmission and SWI/SNF Function
Author(s) -
Zhiqiang Du,
Emily T. Crow,
Hyunil Kang,
Liming Li
Publication year - 2010
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00225-10
Subject(s) - swi/snf , biology , asparagine , glutamine , smarcb1 , chromatin structure remodeling (rsc) complex , microbiology and biotechnology , transcription factor , repressor , chromatin remodeling , amino acid , genetics , gene
We have recently reported that the yeast chromatin-remodeling factor Swi1 can exist as a prion, [SWI + ], demonstrating a link between prionogenesis and global transcriptional regulation. To shed light on how the Swi1 conformational switch influences Swi1 function and to define the sequence and structural requirements for [SWI + ] formation and propagation, we functionally dissected the Swi1 molecule. We show here that the [SWI + ] prion features are solely attributable to the first 327 amino acid residues (N), a region that is asparagine rich. N was aggregated in [SWI+ ] cells but diffuse in [swi− ] cells; chromosomal deletion of the N-coding region resulted in [SWI + ] loss, and recombinant N peptide was able to form infectious amyloid fibersin vitro , enabling [SWI + ]de novo formation through a simple transformation. Although the glutamine-rich middle region (Q) was not sufficient to aggregate in [SWI + ] cells or essential for SWI/SNF function, it significantly modified the Swi1 aggregation pattern and Swi1 function. We also show that excessive Swi1 incurred Li+ /Na+ sensitivity and that the N/Q regions are important for this gain of sensitivity. Taken together, our results provide the final proof of “protein-only” transmission of [SWI + ] and demonstrate that the widely distributed “dispensable” glutamine/asparagine-rich regions/motifs might have important and divergent biological functions.