18
expressed and co-regulated in condition of iron stress. The chief NRPS enzymes
involved in biosynthesis of siderophores in A. fumigatus is encoded by SidD (FC and
TAFC synthesis) and SidC (FC synthesis) (Yasmin et al. 2012). TAFC is produced by
acetylation of FC by the enzyme transacetylase encoded by SidG gene. The activation
of NRPS enzyme is led by PptA (phosphopantetheine transferase enzyme) which
converts apo-NRPS into its activated (holoenzyme) form (von Döhren 2004).
2.3 Screening of Compounds as Inhibitors of Siderophore
Biosynthesis
The general protocol followed for screening the inhibitors of siderophore biosynthesis
is to grow a bacterial culture in iron-limiting conditions. Those compounds which
prevent the growth of bacteria under such conditions are considered as potential candidate. This protocol is more effective in pathogens which have single mechanism for
iron uptake, while those having more than one system for iron acquisition were found
Fig. 2.3 Representation of siderophore biosynthetic pathway
S. Bhatia and S. Singh
expressed and co-regulated in condition of iron stress. The chief NRPS enzymes
involved in biosynthesis of siderophores in A. fumigatus is encoded by SidD (FC and
TAFC synthesis) and SidC (FC synthesis) (Yasmin et al. 2012). TAFC is produced by
acetylation of FC by the enzyme transacetylase encoded by SidG gene. The activation
of NRPS enzyme is led by PptA (phosphopantetheine transferase enzyme) which
converts apo-NRPS into its activated (holoenzyme) form (von Döhren 2004).
2.3 Screening of Compounds as Inhibitors of Siderophore
Biosynthesis
The general protocol followed for screening the inhibitors of siderophore biosynthesis
is to grow a bacterial culture in iron-limiting conditions. Those compounds which
prevent the growth of bacteria under such conditions are considered as potential candidate. This protocol is more effective in pathogens which have single mechanism for
iron uptake, while those having more than one system for iron acquisition were found
Fig. 2.3 Representation of siderophore biosynthetic pathway
S. Bhatia and S. Singh