0000000000870797
AUTHOR
Thomas Lingg
Generation of reporter plasmids containing defined base modifications in the DNA strand of choice
Physiological effects of DNA bases other than A, G, C, and T as well as ways of removal of such bases from genomes are studied intensely. Methods for targeted insertion of modified bases into DNA, therefore, are highly demanded in the fields of DNA repair and epigenetics. This article describes efficient procedures for incorporation of modified DNA bases into a plasmid-borne enhanced green fluorescent protein (EGFP) gene. The procedure exploits excision of a stretch of 18 nt from either the transcribed or nontranscribed DNA strand with the help of the sequence-specific nicking endonucleases Nb.Bpu10I and Nt.Bpu10I. The excised single-stranded oligonucleotide is then swapped for a synthetic …
Mouse CSB protein is important for gene expression in the presence of a single-strand break in the non-transcribed DNA strand.
CSB protein is required for strand-specific repair of bulky DNA lesions in transcribed genes and mediates transcription recovery after exposure to DNA-damaging agents. We enzymatically generated DNA single-strand breaks (SSBs) with 3'-OH and 5'-phosphate termini in defined positions of a plasmid-borne gene and measured their effect on transcription in cell lines with different statuses of the Csb gene. A single SSB in the transcribed region of the gene caused significant decrease of gene expression. In all tested cell lines of mouse and human origin, a SSB in the transcribed DNA strand was less harmful for gene expression than a SSB situated in the opposing DNA strand. CSB deficiency exhibi…