The Schizosaccharomyces pombe inv1 ⁺ Regulatory Region Is Unusually Large and Contains Redundant cis -Acting Elements That Function in a SAGA- and Swi/Snf-Dependent Fashion

Abstract

The Schizosaccharomyces pombe inv1 ؉ gene encodes invertase, the enzyme required for hydrolysis of sucrose and raffinose. Transcription of inv1؉ is regulated by glucose levels, with transcription tightly repressed in high glucose and strongly induced in low glucose. To understand this regulation, we have analyzed the inv1 ؉ cis-regulatory region and the requirement for the transacting coactivators SAGA and Swi/Snf. Surprisingly, deletion of the entire 1-kilobase intergenic region between the inv1 ؉ TATA element and the upstream open reading frame SPCC191.10 does not significantly alter regulation of inv1 ؉ transcription. However, a longer deletion that extends through SPCC191.10 abolishes inv1 ؉ induction in low glucose. Additional analysis demonstrates that there are multiple, redundant regulatory regions spread over 1.5 kb 5= of inv1 ؉ , including within SPCC191.10, that can confer glucose-mediated transcriptional regulation to inv1 ؉ . Furthermore, SPCC191.10 can regulate inv1 ؉ transcription in an orientation-independent fashion and from a distance as great as 3 kb. With respect to trans-acting factors, both SAGA and Swi/Snf are recruited to SPCC191.10 and to other locations in the large inv1؉ regulatory region in a glucose-dependent fashion, and both are required for inv1 ؉ derepression. Taken together, these results demonstrate that inv1 ؉ regulation in S. pombe occurs via the use of multiple regulatory elements and that activation can occur over a great distance, even from elements within other open reading frames.

Transcription of lncRNA prt, clustered prt RNA sites for Mmi1 binding, and RNA polymerase II CTD phospho-sites govern the repression of pho1 gene expression under phosphate-replete conditions in fission yeast

“…2C). The DNA segment from −61 to −5 that is essential for prt transcription contains a candidate TATA box sequence 5 ′ -TATATATA (Ahn et al 2012). The nucleotide sequence of the 110-nt DNA segment flanking the prt start site is shown in Figure 2A.…”

A snapshot of Snf2 enzymes in fission yeast

“…Snf21 is essential for cell viability, since the null mutant strain undergoes only a few rounds of cell division, and a temperature-sensitive snf21 mutant shows severe defects in chromosome segregation and cytokinesis [2,5]. The snf22 + gene, on the other hand, is a nonessential gene and its deletion severely affects chromatin remodelling, histone acetylation, transcriptional response to osmotic stress, expression of the invertase (inv1 + )-encoding gene and meiotic recombination [3,6,7]. Localized chromatin remodelling by Snf22 at the ade6-M26 locus is essential for recruiting the DSB (double-strand break) machinery to chromatin and hence activating the meiotic recombination hotspot [3].…”

Organización de los nucleosomas y regulación del genoma en el género Schizosaccharomyces

“…Muy recientemente se ha publicado un artículo en el que se estudian los diferentes elementos implicados en la regulación en cis del gen inv1 de S. pombe (Ahn et al 2012) y que apoya esta posibilidad. El gen inv1 codifica la única invertasa de esta levadura, una enzima requerida para la hidrólisis de la sacarosa y la rafinosa cuando se utilizan estos azúcares como fuente de carbono .…”

“…DISCUSIÓN 83 Ahn et al (2012) ) y que la secuencia promotora del gen contiene GC-boxes, sitios de unión para el factor de transcripción Scr1, que son responsables de la expresión dependiente de glucosa de la invertasa Ahn et al 2012).…”

“…Por otro lado, los dos motivos de unión que presentan mayor frecuencia en las NDRs de S. japonicus son CHMCACCA y CCCCRCW. Este último se corresponde con el sitio de unión de los factores Rsv1/Scr1 en S. pombe (Hao et al 1997;Tanaka et al 1998;Ahn et al 2012). Es posible que dado el alto contenido en GC de las NDRs en S. japonicus (49% GC frente al 36% de S. pombe y S. octosporus), algunas proteínas cuyas secuencias de unión son muy ricas en C/G desarrollen nuevas funciones para adaptarse a la composición de su genoma.…”