Serine utilization locus in <i>C. jejuni.</i>

<p>(A) The serine utilization locus of <i>C. jejuni</i> consists of the s<i>daCA</i> operon, which is conserved in all sequenced <i>C. jejuni</i> strains. The genes <i>sdaC</i> and <i>sdaA</i> encode for a serine uptake transporter and a L-serine dehydratase, respectively. The intergenic sequence is shown with the <i>sdaA</i> start codon (ATG), the <i>sdaA</i> shine-dalgarno squence (underlined) and the <i>sdaC</i> stop codon (*). Mutants of <i>sdaA</i> and <i>sdaC</i> were constructed by insertion of kanamycin and erythromycin resistance cassettes in respective genes as indicated. (B) Comparison of different <i>C. jejuni</i> wild-type isolates to utilize serine as growth substrate. The shown optical densities are the mean values ±SD that were maximally reached by indicated wild-type <i>C. jejuni</i> strains RM1221, 81116, 305, 327 and DFVF1099 during a growth period of 48 hours in DMEM supplemented with 20 mM of the indicated amino acids.