Proline metabolism in <i>C. jejuni</i> 81-176.

<p>(A) The gene locus of <i>C. jejuni</i> 81-176 encoding the proline permease PutP and the bifunctional proline dehydrogenase PutA is shown. The start codons (bold) and Shine-Dalgarno-sequences (underlined) of <i>putA</i> and <i>putP</i> as well as the intergenic region are indicated below the gene region. (B) Schematic model of the proline uptake system in <i>C. jejuni</i>. After proline is being co-imported with sodium ions by the permease PutP into <i>C. jejuni</i>, the cytoplasmic, bifunctional proline dehydrogenase PutA converts proline into glutamate. (C) The ability of <i>C. jejuni</i> 81-176 wild-type strain, its isogenic <i>putA</i> and <i>putP</i> mutants as well as the complemented <i>putP</i> mutant strains to utilize proline as a growth substrate. Values are the mean ± SD of at least three determinations of maximal reached optical density by <i>C. jejuni</i> 81-176 and its mutant derivates in liquid culture. The growth of <i>C. jejuni</i> in DMEM supplemented with 20 mM glutamate, proline or serine occurred over 24 hours at 37°C in 10% CO₂.