Fig. 5.

Nucleotide sequence and phenotype of EHEC ∆laoB. a Construction of a translationally arrested ∆laoB mutant. Introduction of a point mutation in the DNA sequence of laoB changed the fifth codon encoding glutamine to a premature stop codon. Because of two adjacent mutations, a cut site for the restriction enzyme MnII is deleted at this position. The three point mutations do not influence the AA sequence of the antiparallel overlapping annotated gene ECs5115. b Ratio in percent of EHEC wild type to EHEC ∆laoB after competitive growth. Wild type and mutant were mixed in equal ratios and after 18 h incubation at different growth conditions, their ratio was determined. In 0.5 × LB, no change compared to the inoculation ratio occurred, but when the medium was supplemented with 20 mM L-arginine, EHEC ∆laoB shows a significant growth advantage. The experiment was performed in triplicate (** p < 0.01). c Complementation of EHEC ∆laoB using a plasmid-borne laoB. The diagram shows the ratios in percent of EHEC ∆laoB + pBAD-laoB and EHEC ∆laoB + pBAD-∆laoB after competitive growth. The experiment was performed in triplicate. Significant changes between uninduced and induced conditions are marked with a plus (+ p < 0.05). Significant changes between 0.5 × LB and 0.5 × LB + 20 mM L-arginine are marked with asterisks (** p < 0.01)