Transcription factor Mts1/Mts2 (Atf1/Pcr1, Gad7/Pcr1) activates the M 26 meiotic recombination hotspot in Schizosaccharomyces pombe

Abstract

Homologous recombination hotspots increase the frequency of recombination in nearby DNA. The M26 hotspot in the ade6 gene of Schizosaccharomyces pombe is a meiotic hotspot with a discrete, cis-acting nucleotide sequence (5-ATGACGT-3) defined by extensive mutagenesis. A heterodimeric M26 DNA binding protein, composed of subunits Mts1 and Mts2, has been identified and purified 40,000-fold. Cloning, disruption, and genetic analyses of the mts genes demonstrate that the Mts1͞Mts2 heterodimer is essential for hotspot activity. This provides direct evidence that a specific trans-acting factor, binding to a cis-acting site with a unique nucleotide sequence, is required to activate this meiotic hotspot. Intriguingly, the Mts1͞Mts2 protein subunits are identical to the recently described transcription factors Atf1 (Gad7) and Pcr1, which are required for a variety of stress responses. However, we report differential dependence on the Mts proteins for hotspot activation and stress response, suggesting that these proteins are multifunctional and have distinct activities. Furthermore, ade6 mRNA levels are equivalent in hotspot and nonhotspot meioses and do not change in mts mutants, indicating that hotspot activation is not a consequence of elevated transcription levels. These findings suggest an intimate but separable link between the regulation of transcription and meiotic recombination. Other studies have recently shown that the Mts1͞Mts2 protein and M26 sites are involved in meiotic recombination elsewhere in the S. pombe genome, suggesting that these factors help regulate the timing and distribution of homologous recombination.

A DNA binding motif of meiotic recombinase Rec12 (Spo11) defined by essential glycine-202, and persistence of Rec12 protein after completion of recombination

“…Media were supplemented as necessary with growth factors (amino acids, bases) at 100 μg/ml. Methods for mating, meiosis, and determination of recombinant frequencies were as described (Wahls and Smith, 1994;Kon et al, 1997). The identification and analysis of disomic and diploid spore colonies were as previously described (Krawchuk et al, 1999;Molnar et al, 2001).…”

Regulation of Swi6/HP1-dependent Heterochromatin Assembly by Cooperation of Components of the Mitogen-activated Protein Kinase Pathway and a Histone Deacetylase Clr6

“…Our present findings demonstrate that Atf1 and Pcr1 regulate Swi6-dependent silencing at the mat region independently of cenH-mediated silencing. In our current model, Atf1 and Pcr1 bind specifically to putative ATF/CREB-binding sites upstream of mat3-M (21), as a result of their sequence-specific binding properties (25,30,33); subsequently, they recruit Clr6 histone deacetylase and Swi6 to the mat locus. This hypothesis is consistent with our findings that Atf1 and Pcr1 can form complexes with Clr6 and Swi6 (Fig.…”

Atf1-Pcr1-M26 Complex Links Stress-activated MAPK and cAMP-dependent Protein Kinase Pathways via Chromatin Remodeling of cgs2+

“…The pcr1 mutants also exhibit defects in sexual development (13,16,18), suggesting that Atf1 and Pcr1 may function together in sexual differentiation. However, some stress responses require only Atf1 or Pcr1 (not both) (13,19). This indicates that Atf1, Pcr1, and other bZIP proteins can form different combinations of homodimers and heterodimers, each of which regulates the expression of a specific set of genes in response to a particular stimulus.…”