Figure 5

Effect of recA and recBC mutations on cell growth and chromosome changes. (a) Cell growth. BIK18260 (mcrB1), BIK18261 (mcrBC⁺), BIK18290 (mcrB1 ΔrecA), BIK18291 (mcrBC⁺ ΔrecA), BIK18292 (mcrB1 ΔrecBC) and BIK18293 (mcrBC⁺ΔrecBC), carrying pEF24 (pSC101::pvuIIM, see Table 1), were grown in LB broth with 0.2% glucose and selective antibiotics to exponential phase, diluted to OD600 = 0.1 and further grown with or without 0.0002% arabinose. OD600 was monitored at the indicated time intervals after addition of arabinose. Each value was divided by the value at time zero. (b) Chromosomes in uninduced cells. BIK18261 (mcrBC⁺), BIK18291 (mcrBC⁺ ΔrecA), and BIK18293 (mcrBC⁺ ΔrecBC), and their derivatives carrying pEF24 (pSC101::pvuIIM) were grown in LB broth with 0.2% glucose and selective antibiotics to exponential phase. Chromosomal DNA was prepared and subjected to pulsed-field agarose gel electrophoresis. M, λ DNA ladder. (c) Chromosomes after induction. Chromosome DNA in BIK18261 (mcrBC⁺), BIK18291 (mcrBC⁺ ΔrecA), and BIK18293 (mcrBC⁺ ΔrecBC), carrying pEF24 (pSC101::pvuIIM) after induction of PvuII methyltransferase with 0.002% or 0.0002% arabinose. At the indicated time intervals after induction, chromosomal DNA was prepared and subjected to pulsed-field agarose gel electrophoresis. M1, λ DNA ladder; M2, λ DNA cut with HindIII.