TY  - INPR
A1  - Scheitl, Carolin P. M.
A1  - Mieczkowski, Mateusz
A1  - Schindelin, Hermann
A1  - Höbartner, Claudia
T1  - Structure and mechanism of the methyltransferase ribozyme MTR1
T2  - Nature Chemical Biology
N2  - RNA-catalysed RNA methylation was recently shown to be part of the catalytic repertoire of ribozymes. The methyltransferase ribozyme MTR1 catalyses the site-specific synthesis of 1-methyladenosine (m\(^1\)A) in RNA, using O\(^6\)-methylguanine (m\(^6\)G) as methyl group donor. Here we report the crystal structure of MTR1 at a resolution of 2.8 Å, which reveals a guanine binding site reminiscent of natural guanine riboswitches. The structure represents the postcatalytic state of a split ribozyme in complex with the m1A-containing RNA product and the demethylated cofactor guanine. The structural data suggest the mechanistic involvement of a protonated cytidine in the methyl transfer reaction. A synergistic effect of two 2'-O-methylated ribose residues in the active site results in accelerated methyl group transfer. Supported by these results, it seems plausible that modified nucleotides may have enhanced early RNA catalysis and that metabolite-binding riboswitches may resemble inactivated ribozymes that have lost their catalytic activity during evolution.
KW  - Methyltransferase Ribozyme MTR1
KW  - Crystal structure of MTR1
KW  - RNA-catalyzed RNA methylation
KW  - X-ray crystallography
KW  - RNA
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-272170
ET  - submitted version
ER  - 
TY  - INPR
A1  - Brenner, Marian
A1  - Zink, Christoph
A1  - Witzinger, Linda
A1  - Keller, Angelika
A1  - Hadamek, Kerstin
A1  - Bothe, Sebastian
A1  - Neuenschwander, Martin
A1  - Villmann, Carmen
A1  - von Kries, Jens Peter
A1  - Schindelin, Hermann
A1  - Jeanclos, Elisabeth
A1  - Gohla, Antje
T1  - 7,8-Dihydroxyflavone is a direct inhibitor of pyridoxal phosphatase
T2  - eLife
N2  - Vitamin B6 deficiency has been linked to cognitive impairment in human brain disorders for decades. Still, the molecular mechanisms linking vitamin B6 to these pathologies remain poorly understood, and whether vitamin B6 supplementation improves cognition is unclear as well. Pyridoxal phosphatase (PDXP), an enzyme that controls levels of pyridoxal 5’-phosphate (PLP), the co-enzymatically active form of vitamin B6, may represent an alternative therapeutic entry point into vitamin B6-associated pathologies. However, pharmacological PDXP inhibitors to test this concept are lacking. We now identify a PDXP and age-dependent decline of PLP levels in the murine hippocampus that provides a rationale for the development of PDXP inhibitors. Using a combination of small molecule screening, protein crystallography and biolayer interferometry, we discover and analyze 7,8-dihydroxyflavone (7,8-DHF) as a direct and potent PDXP inhibitor. 7,8-DHF binds and reversibly inhibits PDXP with low micromolar affinity and sub-micromolar potency. In mouse hippocampal neurons, 7,8-DHF increases PLP in a PDXP-dependent manner. These findings validate PDXP as a druggable target. Of note, 7,8-DHF is a well-studied molecule in brain disorder models, although its mechanism of action is actively debated. Our discovery of 7,8-DHF as a PDXP inhibitor offers novel mechanistic insights into the controversy surrounding 7,8-DHF-mediated effects in the brain.
KW  - 7,8-dihydroxyflavone (7,8-DHF)
KW  - pyridoxal phosphatase (PDXP)
KW  - vitamin B6
KW  - PDXP inhibitors
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-350446
ER  -