De Falco Mariarosaria, Massa Federica, Rossi Mosè, De Felice Mariarita
Institute of Biosciences and Bioresources, Consiglio Nazionale delle Ricerche, 80131, Naples, Italy.
Extremophiles. 2018 Jul;22(4):581-589. doi: 10.1007/s00792-018-1018-7. Epub 2018 Feb 27.
ATPase/Helicases and nucleases play important roles in DNA end-resection, a critical step during homologous recombination repair in all organisms. In hyperthermophilic archaea the exo-endonuclease NurA and the ATPase HerA cooperate with the highly conserved Mre11-Rad50 complex in 3' single-stranded DNA (ssDNA) end processing to coordinate repair of double-stranded DNA breaks. Little is known, however, about the assembly mechanism and activation of the HerA-NurA complex. In this study we demonstrate that the NurA exonuclease activity is inhibited by the Sulfolobus solfataricus RecQ-like Hel112 helicase. Inhibition occurs both in the presence and in the absence of HerA, but is much stronger when NurA is in complex with HerA. In contrast, the endonuclease activity of NurA is not affected by the presence of Hel112. Taken together these results suggest that the functional interaction between NurA/HerA and Hel112 is important for DNA end-resection in archaeal homologous recombination.
ATP酶/解旋酶和核酸酶在DNA末端切除过程中发挥着重要作用，这是所有生物体同源重组修复过程中的关键步骤。在嗜热古菌中，外切核酸酶NurA和ATP酶HerA与高度保守的Mre11-Rad50复合物协同作用，进行3'单链DNA（ssDNA）末端加工，以协调双链DNA断裂的修复。然而，关于HerA-NurA复合物的组装机制和激活情况，人们知之甚少。在本研究中，我们证明了嗜热栖热菌RecQ样解旋酶Hel112抑制了NurA核酸外切酶活性。无论有无HerA，这种抑制作用都会发生，但当NurA与HerA形成复合物时，抑制作用更强。相比之下，Hel112的存在并不影响NurA的核酸内切酶活性。综合这些结果表明，NurA/HerA与Hel112之间的功能相互作用对于古菌同源重组中的DNA末端切除至关重要。
