Phenotype Enhancement Screen of a Regulatory spx Mutant Unveils a Role for the ytpQ Gene in the Control of Iron Homeostasis.

ABSTRACT: Spx is a global regulator of genes that are induced by disulfide stress in Bacillus subtilis. Most of the Spx-regulated genes (SRGs) are of unknown function, but many encode products conserved in low %GC Gram positive bacteria. Using a gene-disruption library of B. subtilis genomic mutations, the SRGs were screened for phenotypes related to Spx-controlled activities, such as growth in minimal medium and sensitivity to methylglyoxal, but nearly all of the SRG mutations showed little if any phenotype. To uncover SRG function, the mutations were rescreened in an spx mutant background to determine which mutant SRG allele would enhance the spx mutant phenotype. One of the SRGs, ytpQ, was the site of a mutation that, when combined with an spx null mutation, elevated the severity of the Spx mutant phenotype, as shown by reduced growth in a minimal medium and by hypersensitivity to methylglyoxal. Proteomic and transcriptomic data indicated that the ytpQ mutation caused the derepression of the Fur and PerR regulons, as well as heightened LexA-controlled gene expression. Our study suggests that the ytpQ gene, encoding a conserved DUF1444 protein, functions directly or indirectly in repairing or stabilizing Fe-bearing proteins, which are sensitive to thiol reactive agents and, therefore, likely influenced by Spx-controlled genes. The wild type parent, ytpQ and spx mutants were grown in a glucose minimal medium, with and without 2.8 mM methylglyoxal, to mid-log phase. Cells were harvested and RNA was extracted for microarray hybridization analysis to determine if any changes in the transcriptome could be detected that were attributable to the ytpQ mutation. Microarray hybridizations were performed with RNA from three biological replicates.

ORGANISM(S): Bacillus subtilis

SUBMITTER: Ulrike Mäder 

PROVIDER: E-GEOD-28872 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress