5LLQ: Crystal Structure Of Sulfolobus Solfataricus O6-methylguanine Methyltransferase C119f Variant

BACKGROUND: Alkylated DNA-protein alkyltransferases (AGTs) are conserved proteins that repair alkylation damage in DNA by using a single-step mechanism leading to irreversible alkylation of the catalytic cysteine in the active site. Trans-alkylation induces inactivation and destabilization of the protein, both in vitro and in vivo, likely triggering conformational changes. A complete picture of structural rearrangements occurring during the reaction cycle is missing, despite considerable interest raised by the peculiarity of AGT reaction, and the contribution of a functional AGT in limiting the efficacy of chemotherapy with alkylating drugs. METHODS: As a model for AGTs we have used a thermostable ortholog from the archaeon Sulfolobus solfataricus (SsOGT), performing biochemical, structural, molecular dynamics and in silico analysis of ligand-free, DNA-bound and mutated versions of the protein. RESULTS: Conformational changes occurring during lesion recognition and after the reaction, allowed us to identify a novel interaction network contributing to SsOGT stability, which is perturbed when a bulky adduct between the catalytic cysteine and the alkyl group is formed, a mandatory step toward the permanent protein alkylation. CONCLUSIONS: Our data highlighted conformational changes and perturbation of intramolecular interaction occurring during lesion recognition and catalysis, confirming our previous hypothesis that coordination between the N- and C-terminal domains of SsOGT is important for protein activity and stability. GENERAL SIGNIFICANCE: A general model of structural rearrangements occurring during the reaction cycle of AGTs is proposed. If confirmed, this model might be a starting point to design strategies to modulate AGT activity in therapeutic settings.
PDB ID: 5LLQDownload
MMDB ID: 144823
PDB Deposition Date: 2016/7/28
Updated in MMDB: 2016/12
Experimental Method:
x-ray diffraction
Resolution: 2.7  Å
Source Organism:
Similar Structures:
Biological Unit for 5LLQ: monomeric; determined by author
Molecular Components in 5LLQ
Label Count Molecule
Protein (1 molecule)
Methylated-dna--protein-cysteine Methyltransferase(Gene symbol: SSO_RS12090)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

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