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. 2013 Apr 19;41(11):5817–5826. doi: 10.1093/nar/gkt275

Figure 3.

Figure 3.

Biochemical characterization of P. furiosus RecJ on RNA substrates. The 3′–5′ exonuclease activity of PfRecJ on ssRNA was determined in a buffer consisting of 20 mM Tris–HCl (pH 7.5), 30 mM NaCl, 10 mM KCl, 5 mM DTT, 0.25 mM MnCl2, 100 ng/μl BSA and 4 U Rnsin. Substrates (50 nM) were incubated with 50 nM PfRecJ at 50°C for 0, 2, 5, 10, 20 and 30 min (A and D) or 30 min (B and C). Lowercase and uppercase denote RNA and DNA, respectively. (A) Time course of 16-nt ssRNA digestion by wt PfRecJ. (B) Identification of key residues. Three mutant PfRecJs were used to confirm the conserved amino acid residues essential for exonuclease activity. (C) Effect of 3′ ribonucleotide on ssRNA digestion by PfRecJ. A 16-nt ssRNA with four 3′ ribonucleotides (a, u, c and g) was digested by PfRecJ. (D) Effect of ssRNA length on hydrolysis efficiency. ssRNAs with different lengths (12, 16 and 25 nt) were digested by PfRecJ.