A WblA-binding protein, SpiA, involved in Streptomyces oxidative stress response

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• The wblA gene in Streptomyces coelicolor negatively regulates antibiotic biosynthesis and oxidative stress responses.
• WblA orthologs, like WhcA in Corynebacterium glutamicum, interact with stress-related proteins such as SpiA.
• The interaction between WblA and SpiA orthologs suggests a conserved regulatory mechanism.

Purpose of the Study:

• To identify and characterize a SpiA ortholog in Streptomyces coelicolor that interacts with WblA.
• To investigate the functional role of the WblA-SpiA ortholog interaction in oxidative stress responses.
• To determine how cellular redox status influences this interaction.

Main Methods:

• Heterologous expression in E. coli.
• In vitro pull-down assays to confirm protein-protein interactions.
• Oxidative stress induction using diamide.
• Construction and analysis of a spiAsc-deletion mutant.
• Real-time RT-PCR to quantify gene expression.

Main Results:

• Identified SCO2553 protein (SpiAsc) as a SpiA ortholog interacting with WblA in S. coelicolor.
• Demonstrated specific binding between WblA and SpiAsc, modulated by oxidants like diamide.
• Showed that SpiAsc negatively regulates WblA during oxidative stress.
• A spiAsc-deletion mutant exhibited reduced sensitivity to diamide-induced oxidative stress.
• Oxidative stress response genes (sodF, sodF2, trxB) were upregulated in the spiAsc-deletion mutant.

Conclusions:

• SpiAsc specifically interacts with WblA in S. coelicolor, and this interaction is redox-sensitive.
• SpiAsc plays a negative regulatory role in the oxidative stress response by modulating WblA activity.
• This study reveals a novel regulatory pathway involving SpiAsc and WblA in bacterial stress adaptation.