Non-ribosomal peptide synthetase AsbD is expressed in iron-limited conditions in the bacterial pathogen Aeromonas salmonicida

摘要

Iron is an essential nutrient for most living bacteria. One of the main mechanisms which allow bacterial pathogens to obtain iron is siderophore-mediated iron acquisition. Aeromonas salmonicida subsp. salmonicida, the aetiological agent of furunculosis in fish produces a catecholate siderophore under iron-limiting conditions. A. salmonicida siderophore biosynthesis genes include genes that encode non-ribosomal peptide synthetases. In this study using a siderophore biosynthesis gene cluster previously described, the asbD gene which encodes a non-ribosomal peptide synthetase was studied. Total protein of null mutant and wild-type strains, in iron-repleted and iron-depleted conditions, was extracted and loaded onto polyacrylamide gel. Only the wild-type strain in iron-depleted conditions expressed a 160-KDa protein. These results confirmed that asbD is an iron-regulated gene, and AsbD protein is expressed only in iron-limited conditions.