Redox-dependent disulfide bond formation in SAP30L corepressor protein: Implications for structure and function

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Sin3A-associated protein 30-like (SAP30L) is a component of the Sin3A corepressor complex involved in transcriptional regulation.
• SAP30L's precise function within the complex and its interaction mechanisms remain incompletely understood.
• SAP30L possesses an N-terminal Cys3His type zinc finger (ZnF) motif crucial for molecular interactions.

Purpose of the Study:

• To investigate the redox-dependent regulatory mechanisms of SAP30L structure and function.
• To elucidate the role of disulfide bond formation in the SAP30L ZnF motif.
• To characterize the structural and interactional changes in SAP30L under oxidative stress.

Main Methods:

• High-resolution mass spectrometry to detect disulfide bond formation.
• Solution Nuclear Magnetic Resonance (NMR) spectroscopy to determine protein structure.
• NMR titration experiments to study interactions with lipids and DNA.

Main Results:

• SAP30L forms two specific disulfide bonds (Cys29-Cys30 and Cys38-Cys74) in its ZnF motif upon oxidative stress, releasing the zinc ion.
• The oxidized SAP30L remains folded and retains the ability to bind signaling phospholipids.
• NMR structure reveals a fold similar to SAP30; lipid and DNA binding are mediated by the C-terminal tail and alpha-helices of the SAP30L ZnF.

Conclusions:

• Redox-dependent disulfide bond formation in SAP30L's ZnF motif represents a novel regulatory mechanism.
• Oxidation alters SAP30L's interaction profile, potentially modulating its role in the Sin3A complex and transcriptional regulation.
• The findings provide insights into the dynamic structural changes and interaction capabilities of SAP30L.