DNA Ligase C and Prim-PolC participate in base excision repair in mycobacteria

Prokaryotic Ligase D is a conserved DNA repair apparatus processing DNA double-strand breaks in stationary phase. An orthologous Ligase C (LigC) complex also co-exists in many bacterial species but its function is unknown. Here, we show that the LigC complex interacts with core BER enzymes in vivo and demonstrate that together these factors constitute an excision repair apparatus capable of repairing damaged bases and abasic sites. The polymerase component, which contains a conserved C-terminal structural loop, preferentially binds to and fills-in short gapped DNA intermediates with RNA and LigC ligates the resulting nicks to complete repair. Components of the LigC complex, like LigD, are expressed upon entry into stationary phase and cells lacking either of these pathways exhibit increased sensitivity to oxidising genotoxins. Together, these findings establish that the LigC complex is directly involved in an excision repair pathway(s) that repairs DNA damage with ribonucleotides during stationary phase

Structure of complex oxide nanoparticles in a Fe-14Cr-2W-0.3Ti-0.3Y(2)O(3) ODS RAF steel

One of the most crucial steps in the development of oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steels is the engineering of their microstructure, which includes control of the type and size of oxide nanoparticles. In this work, the composition and crystal structure of oxide particles grown in the Fe-14Cr-2W-0.3Ti-0.3Y(2)O(3) ODS RAF steel were characterized using advanced spectroscopic and microscopic techniques. The electron energy loss spectroscopic mapping has shown presence of numerous fine Y-Ti-O oxides but also larger Cr-Ti-O and Cr-N particles among those extracted from the bulk samples. In addition, atom probe tomography of the as-compacted ODS RAF samples revealed a uniform spatial distribution of fine oxides containing mainly Y, Ti, and O. The orthorhombic YTiO3, having distorted perovskite structure, was identified in all analyzed oxides using HR-STEM and diffraction pattern analysis. (C) 2013 Elsevier B.V. All rights reserved