Salmonella enterica strains lacking the frataxin homolog CyaY show defects in Fe-S cluster metabolism in vivo

Abstract

In Salmonella enterica, the isc operon contains genes necessary for the synthesis of Fe-S clusters and strains lacking this operon have severe defects in a variety of cellular processes. Other cellular loci that impact Fe-S cluster synthesis to a lesser extent have been described. The cyaY locus encodes a frataxin homolog, and it is shown here that lesions in this locus affect Fe-S cluster metabolism. When present in combination with other lesions, mutations in cyaY can result in a strain with more severe defects than those lacking the isc locus.

FIG. 1.

The yggX apbC cyaY mutant has a stringent thiamine requirement. Overnight nutrient cultures were subcultured and grown at 37°C with shaking, as described in reference . Growth of strains was monitored over time by measurement of absorbance (optical density [OD] at 650 nm) with a Bausch and Lomb Spectronic 20. Strains DM7226 (wild type) (•), DM7306 (abpC yggX) (▴), DM7644 (cyaY) (○), and DM7641 (abpC yggX cyaY) (▪) were grown in (A) minimal medium supplemented with adenine (5 mM) and ferric chloride (20 μM) or (B) the same medium as described for panel A but with thiamine (50 μM).

FIG. 2.

Distinct growth pattern of a yggX apbC cyaY mutant in rich medium. Strains were grown and subcultured as described in the legend for Fig. 1. Growth in (A) nutrient broth and (B) Luria broth is shown for strains DM7641 (abpC yggX cyaY) (▴), DM7642 (apbC cyaY) (○), DM7643 (yggX cyaY) (▪), and DM7644 (cyaY) (•). hrs, hours.