Publications

• Crystal structure of the FTO protein reveals basis for its substrate specificity.

  Han Z., Niu T., Chang J., Lei X., Zhao M., Wang Q., Cheng W., Wang J., Feng Y., Chai J.

  Recent studies have unequivocally associated the fat mass and obesity-associated (FTO) gene with the risk of obesity. In vitro FTO protein is an AlkB-like DNA/RNA demethylase with a strong preference for 3-methylthymidine (3-meT) in single-stranded DNA or 3-methyluracil (3-meU) in single-stranded ... >> More

  Recent studies have unequivocally associated the fat mass and obesity-associated (FTO) gene with the risk of obesity. In vitro FTO protein is an AlkB-like DNA/RNA demethylase with a strong preference for 3-methylthymidine (3-meT) in single-stranded DNA or 3-methyluracil (3-meU) in single-stranded RNA. Here we report the crystal structure of FTO in complex with the mononucleotide 3-meT. FTO comprises an amino-terminal AlkB-like domain and a carboxy-terminal domain with a novel fold. Biochemical assays show that these two domains interact with each other, which is required for FTO catalytic activity. In contrast with the structures of other AlkB members, FTO possesses an extra loop covering one side of the conserved jelly-roll motif. Structural comparison shows that this loop selectively competes with the unmethylated strand of the DNA duplex for binding to FTO, suggesting that it has an important role in FTO selection against double-stranded nucleic acids. The ability of FTO to distinguish 3-meT or 3-meU from other nucleotides is conferred by its hydrogen-bonding interaction with the two carbonyl oxygen atoms in 3-meT or 3-meU. Taken together, these results provide a structural basis for understanding FTO substrate-specificity, and serve as a foundation for the rational design of FTO inhibitors. << Less

  Nature 464:1205-1209(2010) [PubMed] [EuropePMC]

• N6-methyladenosine in nuclear RNA is a major substrate of the obesity-associated FTO.

  Jia G., Fu Y., Zhao X., Dai Q., Zheng G., Yang Y., Yi C., Lindahl T., Pan T., Yang Y.G., He C.

  We report here that fat mass and obesity-associated protein (FTO) has efficient oxidative demethylation activity targeting the abundant N6-methyladenosine (m(6)A) residues in RNA in vitro. FTO knockdown with siRNA led to increased amounts of m(6)A in mRNA, whereas overexpression of FTO resulted in ... >> More

  We report here that fat mass and obesity-associated protein (FTO) has efficient oxidative demethylation activity targeting the abundant N6-methyladenosine (m(6)A) residues in RNA in vitro. FTO knockdown with siRNA led to increased amounts of m(6)A in mRNA, whereas overexpression of FTO resulted in decreased amounts of m(6)A in human cells. We further show the partial colocalization of FTO with nuclear speckles, which supports the notion that m(6)A in nuclear RNA is a major physiological substrate of FTO. << Less

  Nat. Chem. Biol. 7:885-887(2011) [PubMed] [EuropePMC]

• Oxidative demethylation of 3-methylthymine and 3-methyluracil in single-stranded DNA and RNA by mouse and human FTO.

  Jia G., Yang C.G., Yang S., Jian X., Yi C., Zhou Z., He C.

  The human obesity susceptibility gene, FTO, encodes a protein that is homologous to the DNA repair AlkB protein. The AlkB family proteins utilize iron(II), alpha-ketoglutarate (alpha-KG) and dioxygen to perform oxidative repair of alkylated nucleobases in DNA and RNA. We demonstrate here the oxida ... >> More

  The human obesity susceptibility gene, FTO, encodes a protein that is homologous to the DNA repair AlkB protein. The AlkB family proteins utilize iron(II), alpha-ketoglutarate (alpha-KG) and dioxygen to perform oxidative repair of alkylated nucleobases in DNA and RNA. We demonstrate here the oxidative demethylation of 3-methylthymine (3-meT) in single-stranded DNA (ssDNA) and 3-methyluracil (3-meU) in single-stranded RNA (ssRNA) by recombinant human FTO protein in vitro. Both human and mouse FTO proteins preferentially repair 3-meT in ssDNA over other base lesions tested. They showed negligible activities against 3-meT in double-stranded DNA (dsDNA). In addition, these two proteins can catalyze the demethylation of 3-meU in ssRNA with a slightly higher efficiency over that of 3-meT in ssDNA, suggesting that methylated RNAs are the preferred substrates for FTO. << Less

  FEBS Lett. 582:3313-3319(2008) [PubMed] [EuropePMC]

• Structures of human ALKBH5 demethylase reveal a unique binding mode for specific single-stranded N6-methyladenosine RNA demethylation.

  Xu C., Liu K., Tempel W., Demetriades M., Aik W., Schofield C.J., Min J.

  N(6)-Methyladenosine (m(6)A) is the most prevalent internal RNA modification in eukaryotes. ALKBH5 belongs to the AlkB family of dioxygenases and has been shown to specifically demethylate m(6)A in single-stranded RNA. Here we report crystal structures of ALKBH5 in the presence of either its cofac ... >> More

  N(6)-Methyladenosine (m(6)A) is the most prevalent internal RNA modification in eukaryotes. ALKBH5 belongs to the AlkB family of dioxygenases and has been shown to specifically demethylate m(6)A in single-stranded RNA. Here we report crystal structures of ALKBH5 in the presence of either its cofactors or the ALKBH5 inhibitor citrate. Catalytic assays demonstrate that the ALKBH5 catalytic domain can demethylate both single-stranded RNA and single-stranded DNA. We identify the TCA cycle intermediate citrate as a modest inhibitor of ALKHB5 (IC50, ∼488 μm). The structural analysis reveals that a loop region of ALKBH5 is immobilized by a disulfide bond that apparently excludes the binding of dsDNA to ALKBH5. We identify the m(6)A binding pocket of ALKBH5 and the key residues involved in m(6)A recognition using mutagenesis and ITC binding experiments. << Less

  J. Biol. Chem. 289:17299-17311(2014) [PubMed] [EuropePMC]

• ALKBH5 is a mammalian RNA demethylase that impacts RNA metabolism and mouse fertility.

  Zheng G., Dahl J.A., Niu Y., Fedorcsak P., Huang C.M., Li C.J., Vagbo C.B., Shi Y., Wang W.L., Song S.H., Lu Z., Bosmans R.P., Dai Q., Hao Y.J., Yang X., Zhao W.M., Tong W.M., Wang X.J., Bogdan F., Furu K., Fu Y., Jia G., Zhao X., Liu J., Krokan H.E., Klungland A., Yang Y.G., He C.

  N(6)-methyladenosine (m(6)A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as another mammalian demethylase that oxidatively reverses m(6)A in mRNA in vitro and in vivo. This demethylation activity of ALKBH5 significantly affects mR ... >> More

  N(6)-methyladenosine (m(6)A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as another mammalian demethylase that oxidatively reverses m(6)A in mRNA in vitro and in vivo. This demethylation activity of ALKBH5 significantly affects mRNA export and RNA metabolism as well as the assembly of mRNA processing factors in nuclear speckles. Alkbh5-deficient male mice have increased m(6)A in mRNA and are characterized by impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes. In accordance with this defect, we have identified in mouse testes 1,551 differentially expressed genes that cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. The discovery of this RNA demethylase strongly suggests that the reversible m(6)A modification has fundamental and broad functions in mammalian cells. << Less

  Mol. Cell 49:18-29(2013) [PubMed] [EuropePMC]

• Structure of human RNA N6-methyladenine demethylase ALKBH5 provides insights into its mechanisms of nucleic acid recognition and demethylation.

  Aik W., Scotti J.S., Choi H., Gong L., Demetriades M., Schofield C.J., McDonough M.A.

  ALKBH5 is a 2-oxoglutarate (2OG) and ferrous iron-dependent nucleic acid oxygenase (NAOX) that catalyzes the demethylation of N(6)-methyladenine in RNA. ALKBH5 is upregulated under hypoxia and plays a role in spermatogenesis. We describe a crystal structure of human ALKBH5 (residues 66-292) to 2.0 ... >> More

  ALKBH5 is a 2-oxoglutarate (2OG) and ferrous iron-dependent nucleic acid oxygenase (NAOX) that catalyzes the demethylation of N(6)-methyladenine in RNA. ALKBH5 is upregulated under hypoxia and plays a role in spermatogenesis. We describe a crystal structure of human ALKBH5 (residues 66-292) to 2.0 Å resolution. ALKBH5₆₆₋₂₉₂ has a double-stranded β-helix core fold as observed in other 2OG and iron-dependent oxygenase family members. The active site metal is octahedrally coordinated by an HXD…H motif (comprising residues His204, Asp206 and His266) and three water molecules. ALKBH5 shares a nucleotide recognition lid and conserved active site residues with other NAOXs. A large loop (βIV-V) in ALKBH5 occupies a similar region as the L1 loop of the fat mass and obesity-associated protein that is proposed to confer single-stranded RNA selectivity. Unexpectedly, a small molecule inhibitor, IOX3, was observed covalently attached to the side chain of Cys200 located outside of the active site. Modelling substrate into the active site based on other NAOX-nucleic acid complexes reveals conserved residues important for recognition and demethylation mechanisms. The structural insights will aid in the development of inhibitors selective for NAOXs, for use as functional probes and for therapeutic benefit. << Less

  Nucleic Acids Res. 42:4741-4754(2014) [PubMed] [EuropePMC]

• Crystal structures of the human RNA demethylase Alkbh5 reveal basis for substrate recognition.

  Feng C., Liu Y., Wang G., Deng Z., Zhang Q., Wu W., Tong Y., Cheng C., Chen Z.

  N(6)-Methylation of adenosine is the most ubiquitous and abundant modification of nucleoside in eukaryotic mRNA and long non-coding RNA. This modification plays an essential role in the regulation of mRNA translation and RNA metabolism. Recently, human AlkB homolog 5 (Alkbh5) and fat mass- and obe ... >> More

  N(6)-Methylation of adenosine is the most ubiquitous and abundant modification of nucleoside in eukaryotic mRNA and long non-coding RNA. This modification plays an essential role in the regulation of mRNA translation and RNA metabolism. Recently, human AlkB homolog 5 (Alkbh5) and fat mass- and obesity-associated protein (FTO) were shown to erase this methyl modification on mRNA. Here, we report five high resolution crystal structures of the catalytic core of Alkbh5 in complex with different ligands. Compared with other AlkB proteins, Alkbh5 displays several unique structural features on top of the conserved double-stranded β-helix fold typical of this protein family. Among the unique features, a distinct "lid" region of Alkbh5 plays a vital role in substrate recognition and catalysis. An unexpected disulfide bond between Cys-230 and Cys-267 is crucial for the selective binding of Alkbh5 to single-stranded RNA/DNA by bringing a "flipping" motif toward the central β-helix fold. We generated a substrate binding model of Alkbh5 based on a demethylation activity assay of several structure-guided site-directed mutants. Crystallographic and biochemical studies using various analogs of α-ketoglutarate revealed that the active site cavity of Alkbh5 is much smaller than that of FTO and preferentially binds small molecule inhibitors. Taken together, our findings provide a structural basis for understanding the substrate recognition specificity of Alkbh5 and offer a foundation for selective drug design against AlkB members. << Less

  J. Biol. Chem. 289:11571-11583(2014) [PubMed] [EuropePMC]