Effect of the K44A mutation of GguA on protein expression and strain growth ability. (A) Expression level of GguA in the gguA deletion strain AB510 carrying 6His-tagged wild-type gguA (pJZ20, lane 2), 6His-tagged K44A gguA mutant (pJZ21, lane 3), or vector control (pBBR1MCS-5, lane 1). (B) Growth curves of gguA mutant AB510 carrying wild-type gguA (pJZ18), 6His-tagged wild-type gguA (pJZ20), 6His-tagged K44A gguA mutant (pJZ21), or vector control (pBBR1MCS-5). The strains were grown in minimal medium containing 10 mM arabinose. Data are the averages of triplicate values with standard deviations.