(3r)-hydroxyacyl-acp dehydratase enzymes used in the biosynthesis of mycolic acids and use of same for screening antibiotics

A purified and isolated enzyme, involved in the FAS II system and having the following characteristics:

• a) it is constituted of a dimer or a multimer selected from the group consisting of:
• (i) homomultimers comprising at least three identical proteins comprising a hydratase 2 motif [YF]-x(1,2)-[LIVG]-[STGCFG-D-x-N-P-[LIV]-H-x(5)-[AS] (SEQ ID No. 15), (which x(n) represents any n amino acids, and the amino acids between square brackets representing alternatives), or a catalytic motif derived from the hydratase 2 motif and constituted at least of the basic motif D-x(4) H, in which x(4) represents any 4 amino acids, or a motif similar to the basic motif,
• (ii) heterodimers and heteromultimers comprising:
• at least two different proteins as defined in (i), or
• one or more proteins as defined in (i) and of one or more proteins not comprising a hydratase 2 motif, but the three-dimensional structure of which exhibits a hotdog fold;
• and
• b) it catalyzes at least one of the dehydration of a (3R)-hydroxyacyl substrate to give 2 trans-enoyl and the hydration of a 2 trans-enoyl substrate to give (3R)-hydroxyacyl, in accordance with scheme (I):
• in which X represents ACP and n≧0, or CoA and n≧0.