SLX4 assembles a telomere maintenance toolkit by bridging multiple endonucleases with telomeres

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The SLX4 protein complex is involved in DNA metabolism and interacts with telomeric protein TRF2.
• The precise molecular mechanisms of SLX4 and TRF2 interactions at telomeres are not fully understood.

Purpose of the Study:

• To elucidate the structural basis of the SLX4-TRF2 interaction at human telomeres.
• To map the interactions between SLX4 and its associated endonucleases (SLX1, XPF, MUS81).
• To understand the role of these interactions in telomere length regulation.

Main Methods:

• X-ray crystallography to determine the structure of the SLX4-TRF2 complex.
• Mapping of protein-protein interactions between SLX4 and various endonucleases.
• Analysis of telomeric localization and protein levels of SLX4 and TRF2.

Main Results:

• The crystal structure of the TRF2-binding motif of SLX4 (SLX4TBM) complexed with the TRFH domain of TRF2 (TRF2TRFH) was determined.
• TRF2 recognizes a specific HxLxP motif on SLX4.
• Telomeric localization of SLX4 and associated nucleases depends on SLX4-endonuclease and SLX4-TRF2 interactions.

Conclusions:

• SLX4, in complex with TRF2, forms a scaffold that recruits multiple endonucleases to telomeres.
• This complex negatively regulates telomere length through SLX1-catalyzed resolution of telomere DNA structures.
• The SLX4-TRF2 complex is essential for recombination-based telomere maintenance.