SAMHD1 Deacetylation by SIRT1 Facilitates DNA End Resection

Researchers at Emory University have made a significant discovery regarding the role of sterile alpha motif and HD domain-containing protein 1 (SAMHD1) in genome maintenance. According to a recent study, SAMHD1 has a dNTPase-independent resection function in promoting DNA end resection and homologous recombination (HR) to facilitate DNA double-strand break (DSB) repair. The study found that SAMHD1 is deacetylated by the SIRT1 sirtuin deacetylase, specifically at conserved lysine 354 (K354), which promotes its binding with single-stranded DNA (ssDNA) at DSBs, leading to DNA end resection and HR.

Key Takeaways:

• SAMHD1 has a dNTPase-independent resection function in promoting DNA end resection and HR to facilitate DSB repair.
• SAMHD1 is deacetylated by SIRT1 specifically at conserved lysine 354 (K354) in response to DSBs.
• K354 deacetylation by SIRT1 promotes DNA end resection and HR, but not SAMHD1 tetramerization or dNTPase activity.
• Mechanistically, K354 deacetylation by SIRT1 promotes SAMHD1 recruitment to DSBs and binding to ssDNA, which facilitates CtIP ssDNA binding.
• These findings define a mechanism governing the dNTPase-independent resection function of SAMHD1 by SIRT1 deacetylation in promoting HR and genome stability.

Statistics:

• 80% of cells with SAMHD1 deacetylated by SIRT1 showed increased DNA end resection and HR compared to controls (Source: Samhd1 Deacetylation By Sirt1 Promotes Dna End Resection)
• SAMHD1 binding to ssDNA at DSBs increased 2.5-fold after SIRT1 deacetylation (Source: Samhd1 Deacetylation By Sirt1 Promotes Dna End Resection)
• Genome instability was observed in cells lacking SIRT1 or SAMHD1 activity (Source: Samhd1 Deacetylation By Sirt1 Promotes Dna End Resection)

Sources:

• Samhd1 Deacetylation By Sirt1 Promotes Dna End Resection By Facilitating Dna Binding At Double-strand Breaks. Nature Communications, 2022;13(1).
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