Abstract
BackgroundStress-activated protein kinases regulate multiple cellular responses to a wide variety of intracellular and extracellular conditions. The conserved, multifunctional, ATF/CREB protein Atf1 (Mts1, Gad7) of fission yeast binds to CRE-like (M26) DNA sites. Atf1 is phosphorylated by the conserved, p38-family kinase Spc1 (Sty1, Phh1) and is required for many Spc1-dependent stress responses, efficient sexual differentiation, and activation of Rec12 (Spo11)-dependent meiotic recombination hotspots like ade6-M26.Methodology/Principal FindingsWe sought to define mechanisms by which Spc1 regulates Atf1 function at the ade6-M26 hotspot. The Spc1 kinase was essential for hotspot activity, but dispensable for basal recombination. Unexpectedly, a protein lacking all eleven MAPK phospho-acceptor sites and detectable phosphorylation (Atf1-11M) was fully proficient for hotspot recombination. Furthermore, tethering of Atf1 to ade6 in the chromosome by a heterologous DNA binding domain bypassed the requirement for Spc1 in promoting recombination.Conclusions/SignificanceThe Spc1 protein kinase regulates the pathway of Atf1-promoted recombination at or before the point where Atf1 binds to chromosomes, and this pathway regulation is independent of the phosphorylation status of Atf1. Since basal recombination is Spc1-independent, the principal function of the Spc1 kinase in meiotic recombination is to correctly position Atf1-promoted recombination at hotspots along chromosomes. We also propose new hypotheses on regulatory mechanisms for shared (e.g., DNA binding) and distinct (e.g., osmoregulatory vs. recombinogenic) activities of multifunctional, stress-activated protein Atf1.
Highlights
Homologous recombination is induced to high levels in meiosis and produces crossover recombination structures that help to align paired homologous chromosomes on the metaphase plate in preparation for the first meiotic division [1]
Conclusions/Significance: The Spc1 protein kinase regulates the pathway of Atf1-promoted recombination at or before the point where Atf1 binds to chromosomes, and this pathway regulation is independent of the phosphorylation status of Atf1
In the spc1D mutants, recombination at M26 was decreased to basal (M375) levels, which confirms that the Spc1 protein kinase is essential for hotspot activity [12]
Summary
Homologous recombination is induced to high levels in meiosis and produces crossover recombination structures that help to align paired homologous chromosomes on the metaphase plate in preparation for the first (reductional) meiotic division [1]. The ade6M26 allele promotes meiotic (but not mitotic) recombination [7] This allele has a single base pair substitution [8,9] which created a seven base pair, CRE-like DNA site (M26, 59-ATGACGT-39) [10] that is bound by Atf1-Pcr (Mts1-Mts2) heterodimer in vitro [11] and in vivo [12]. (The DNA binding domain of each protomer binds to one half-site of the whole DNA site that is recognized by the heterodimer.) Engineered and naturally occurring M26 or M26-like DNA sites elsewhere in the fission yeast genome are hotspots and, to the extent tested, their mechanism of function recapitulates that at ade6-M26 [15,16]. Atf is phosphorylated by the conserved, p38-family kinase Spc (Sty, Phh1) and is required for many Spc1-dependent stress responses, efficient sexual differentiation, and activation of Rec (Spo11)-dependent meiotic recombination hotspots like ade6-M26
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
