Skip to main content
. 2004 Nov 25;24(1):180–189. doi: 10.1038/sj.emboj.7600485

Figure 4.

Figure 4

UvrD helicase but not Rep helicase inhibits strand exchange catalysed by RecA. (A) Scheme of DNA strand exchange reaction (ssc, single-stranded circular DNA; dsl, double-stranded linear DNA; jm, joint molecules; nc, nicked circular double-stranded DNA; ssl, single-stranded linear DNA). (B) After RecA nucleoprotein filament formation by preincubation of ssDNA with RecA and SSB proteins, various amounts of UvrD helicase were added simultaneously with 32P end-labelled linear dsDNA, which initiates the strand exchange (lane 1: labelled dsl; lanes 2–7 correspond to 0, 600, 300, 150, 75, 37.5 and 18.75 nM UvrD, respectively). After incubation for 40 min at 37°C, reaction mixture was deproteinized and resolved onto a 0.8% agarose gel. (C) Same as in (B) except that Rep was used in place of UvrD (lanes 1–6 correspond to 0, 1400, 1000, 600, 300 and 150 nM Rep, respectively). (D) Quantification of the reactions shown in panels B and C. (E) Comparable ATPase activities of UvrD and Rep proteins. Reactions containing 1 mM ATP, saturating amount of synthetic oligo(dT)55 (5.5 μM nucleotides) and increasing amount of proteins were incubated at 37°C for 15 min. The calculated amount of ATP hydrolysed linked to the oxidation of NADH was determined by measuring the OD at 340 nm.

HHS Vulnerability Disclosure