Isolation and identification of novel ADP-ribosylated proteins from Streptomyces coelicolor A3(2)

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Protein ADP-ribosylation is implicated in bacterial morphogenesis.
• Previous studies suggested a role for ADP-ribosylation in bacterial development.

Purpose of the Study:

• To identify novel protein targets of ADP-ribosylation in Streptomyces coelicolor.
• To elucidate the functional significance of ADP-ribosylation in bacterial physiology.

Main Methods:

• Late growth phase Streptomyces coelicolor A3(2) cultures were analyzed.
• Proteins undergoing ADP-ribosylation were identified.
• Chemical treatments (e.g., mercuric chloride) were used to characterize the modification.

Main Results:

• Four proteins (MalE, BldKB, a branched-chain amino acid-binding periplasmic protein, and a periplasmic solute-binding protein) were identified as new targets for ADP-ribosylation.
• These proteins are involved in regulating metabolite or nutrient transport across the membrane.
• ADP-ribosylation appears to occur on cysteine residues, indicated by removal with mercuric chloride.
• The modification site may overlap with sites for lipoprotein modification essential for protein export.

Conclusions:

• This study provides the first evidence that proteins involved in bacterial membrane transport can be ADP-ribosylated.
• ADP-ribosylation of these transport proteins may play a regulatory role in nutrient uptake and cellular processes.
• The findings open new avenues for understanding the complex roles of post-translational modifications in bacterial physiology.