Human and bacterial oxidative demethylases repair alkylation damage in both RNA and DNA

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• DNA repair is crucial for genome integrity, preventing diseases like cancer.
• DNA alkylation damage is repaired by mechanisms like oxidative demethylation via E. coli AlkB.
• The cellular response to RNA alkylation damage remains largely unknown.

Purpose of the Study:

• To investigate the DNA repair capabilities of human AlkB homologues, hABH2 and hABH3.
• To determine if hABH2 and hABH3 can repair RNA alkylation damage.
• To elucidate the distinct roles of hABH2 and hABH3 in cellular response to alkylation damage.

Main Methods:

• Investigated oxidative DNA demethylation by hABH2 and hABH3.
• Assessed RNA repair activity of hABH2 and hABH3 using methylated RNA bacteriophage MS2.
• Examined substrate preferences (single-stranded vs. double-stranded nucleic acids) and subnuclear localization of hABH2 and hABH3.

Main Results:

• hABH2 and hABH3 function as oxidative DNA demethylases.
• hABH3, similar to E. coli AlkB, repairs RNA alkylation damage, while hABH2 does not.
• AlkB and hABH3 show preference for single-stranded nucleic acids, whereas hABH2 is more efficient on double-stranded DNA.
• Expression of AlkB and hABH3 in E. coli reactivated methylated RNA bacteriophage MS2 in vivo.

Conclusions:

• RNA repair by hABH3 represents a significant cellular defense mechanism against alkylation damage.
• Distinct catalytic properties and subnuclear localization suggest specialized roles for hABH2 and hABH3 in alkylation damage response.
• This study highlights the importance of RNA repair in maintaining cellular health and genome integrity.