US rhetoric masks absence of fresh North Korea policy

Significance South Korea’s unification minister (MOU) warned on April 10 that any US strike on North Korea would put “the safety of the public” at risk. A day later, Seoul’s defence (MND) and foreign (MFA) ministries dismissed rumours on local social media of an imminent war crisis as “overblown” and “groundless”, respectively. Moon Jae-in, the liberal opposition candidate whom most polls predict will win the May 9 snap presidential election, said he does not expect a US pre-emptive strike on the North. However, Moon also warned Washington that South Korea is “the concerned party” which “owns” peninsula-related matters, including the nuclear issue. Impacts Experienced military professionals in Trump’s cabinet and National Security Council are a restraining influence. South Korea and Japan, being in the front line, will counsel their US protector against any action that might imperil their security. If Moon Jae-in is elected, his desire to re-engage the North will clash with Trump’s hard-line attitude and narrow nuclear focus. After his smooth -- if insubstantial -- summit with Xi, Trump’s threatened unilateralism on North Korea is likely to stop at sanctions.

Rec2 Interplay with both Brh2 and Rad51 Balances Recombinational Repair in Ustilago maydis

ABSTRACT Rec2 is the single Rad51 paralog in Ustilago maydis. Here, we find that Rec2 is required for radiation-induced Rad51 nuclear focus formation but that Rec2 foci form independently of Rad51 and Brh2. Brh2 foci also form in the absence of Rad51 and Rec2. By coprecipitation from cleared extracts prepared from Escherichia coli cells expressing the proteins, we found that Rec2 interacts physically not only with Rad51 and itself but also with Brh2. Transgenic expression of Brh2 in rec2 mutants can effectively restore radiation resistance, but the frequencies of spontaneous Rad51 focus formation and allelic recombination are elevated. The Dss1-independent Brh2-RPA70 fusion protein is also active in restoring radiation sensitivity of rec2 but is hyperactive to an extreme degree in allelic recombination and in suppressing the meiotic block of rec2. However, the high frequency of chromosome missegregation in meiotic products is an indicator of a corrupted process. The results demonstrate that the importance of Rec2 function is not only in stimulating recombination activity but also in ensuring that recombination is properly controlled.

DNA Cross-Link Repair Protein SNM1A Interacts with PIAS1 in Nuclear Focus Formation

ABSTRACT The yeast SNM1/PSO2 gene specifically functions in DNA interstrand cross-link (ICL) repair, and its role has been suggested to be separate from other DNA repair pathways. In vertebrates, there are three homologs of SNM1 (SNM1A, SNM1B, and SNM1C/Artemis; SNM1 family proteins) whose functions are largely unknown. We disrupted each of the SNM1 family genes in the chicken B-cell line DT40. Both SNM1A- and SNM1B-deficient cells were sensitive to cisplatin but not to X-rays, whereas SNM1C/Artemis-deficient cells exhibited sensitivity to X-rays but not to cisplatin. SNM1A was nonepistatic with XRCC3 (homologous recombination), RAD18 (translesion synthesis), FANCC (Fanconi anemia), and SNM1B in ICL repair. SNM1A protein formed punctate nuclear foci depending on the conserved SNM1 (metallo-β-lactamase) domain. PIAS1 was found to physically interact with SNM1A, and they colocalized at nuclear foci. Point mutations in the SNM1 domain, which disrupted the interaction with PIAS1, led to mislocalization of SNM1A in the nucleus and loss of complementation of snm1a cells. These results suggest that interaction between SNM1A and PIAS1 is required for ICL repair.