Effect of hemK knockout and its suppressor mutation on
bacterial growth. A fresh overnight culture of each strain was diluted
to about 10 klett units (with filter no. 66) in 5 ml of medium and
shaken at 37°C. The cell density was determined at intervals, and
representative results of the experiments are shown. (a)
The growth defect of the hemK knockout strain and
complementation by hemK in an expression plasmid. CA293
(hemK+) and CK783 (ΔhemK)
were transformed with pAR-hemK or its vector control, pAR3K. The growth
of each transformant was examined in casamino acid broth. Essentially
the same results were obtained in LB broth. Strains: ■,
CA293 pAR3K; □, CK783 pAR3K; ○, CK783 pAR-hemK;
x, CK783 pAR-hemK (for x, hemK was induced by adding 50
mg/liter arabinose to the medium at time 0). (b) The
growth of the suppressor mutant was compared with that of the
hemK+ and ΔhemK strains in
LB broth. Strains: ■, LE392
(hemK+); □, LK783
(ΔhemK); ○, LLR201 (one of the suppressor
mutants of ΔhemK). (c) The growth of
ΔhemK strain transformed with wild-type or mutant
prfB in a plasmid was compared with that of the
hemK+ or ΔhemK strain in LB
broth. Strains: ■, CA293 pMW218 (vector control);
□, CK783 pMW218; ▵, CK783 pMW-prfB; ◊, CK783
pMW-prfB(A737G).