title: Identification of Uhp1, a ubiquitinated histone-like protein, as a target/mediator of Rhp6 in mating-type silencing in fission yeast.
creator: Naresh, Alpana
creator: Saini, Sharanjot
creator: Singh, Jagmohan
subject: QD Chemistry
description: Mating-type silencing in Schizosaccharomyces pombe is brought about by cooperative interactions between cis-acting DNA sequences flanking mat2P and mat3M and the trans-acting factors, namely Swi6, Clr1-Clr4, Clr6, and Rik1. In addition, DNA repair gene rhp6, which plays a role in post-replication DNA repair and ubiquitination of proteins including histones, is also involved in silencing, albeit in a unique way; its effect on silencing and chromatin structure of the donor loci is dependent on their switching competence. Earlier, we hypothesized the existence of a mediator of Rhp6 that plays a role in reestablishment of the chromatin structure coincidentally with DNA replication associated with mating-type switching. Here we report the identification of a 22-kDa protein as an in vivo target and mediator of Rhp6 in mating-type silencing. The level of this protein is greatly elevated in sng1-1/rhp6(-) mutant and rhp6Delta as compared with wild type strain. Both the deletion and overexpression of the gene encoding this protein elicit switching-dependent loss of silencing. Furthermore, the 22-kDa protein undergoes Rhp6-dependent multiubiquitination and associates with mat2 locus during S phase in wild type cells. Interestingly, it contains a histone-fold motif similar to that of histone H2A, and like histone H2A, it interacts strongly with histone H2B in vitro. These results indicate that the 22-kDa protein, renamed as the ubiquitinated histone-like protein Uhp1, is an in vivo target/mediator of Rhp6 in silencing. Thus, regulation of association of Uhp1 with chromatin and ubiquitination followed by degradation may play a role in reestablishment of inactive chromatin structure at the silent mating-type loci.
publisher: ASBMB
date: 2003-03-14
type: Article
type: PeerReviewed
format: application/pdf
identifier: http://crdd.osdd.net/open/255/1/jagmohan2002.pdf
relation: http://www.jbc.org/content/278/11/9185.long
identifier:   Naresh, Alpana and Saini, Sharanjot and Singh, Jagmohan  (2003) Identification of Uhp1, a ubiquitinated histone-like protein, as a target/mediator of Rhp6 in mating-type silencing in fission yeast.  The Journal of biological chemistry, 278 (11).  pp. 9185-94.  ISSN 0021-9258     
relation: http://crdd.osdd.net/open/255/