PXD038070

PXD038070 is an original dataset announced via ProteomeXchange.

Title	Structure and Mechanism of the atypical Trypanosoma brucei DOT1A histone H3K76 methyltransferase
Description	The early-branched kinetoplastid Trypanosoma brucei encodes an essential histone H3 lysine 76 (H3K76) di-methyltransferase, DOT1A, and a non-essential H3K76 tri-methyltransferase, DOT1B, unlike most eukaryotes of the main lineage that possess only a single DOT1 enzyme. Profound mechanistic differences exist between DOT1 enzymes of these groups, exemplified by the ability of DOT1A to methylate H3K76 in vivo without histone H4 tail interaction, which is essential for yeast and human DOT1 activity. Here, we present crystal structures of T. brucei DOT1A in complex with its co-factor product S-adenosyl-L-homocysteine (AdoHcy). The divergent N-terminal sequence folds into a unique Zn-coordinating beta-hairpin and an alpha-helix, while the methyltransferase domain is structurally conserved across DOT1 enzymes. A notable difference in the DOT1A catalytic domain refers to the disordered active-site loop FH, which in yeast and humans is well-structured due to interactions of motif X residues not present in DOT1A. Two kinetoplastid-specific residues in loop FH, Lys110 and Arg105, are important for DOT1A catalysis, possibly by positioning the target lysine for methyl transfer as deduced from a DOT1A-nucleosome model. DOT1A prefers H3K76me0 ~10 times over H3K76me1 as a substrate, while DOT1B methyltransferase activity from me0 to me1 is 2.6-fold slower than DOT1A, suggesting that DOT1A is the major enzyme producing H3K76me1 and required for subsequent methylation by DOT1B. Our findings provide a mechanistic basis of unique catalytic properties of atypical H3K76 methyltransferases found in kinetoplastids and can explain the need for two DOT1 enzymes to maintain the cell cycle-dependent H3K76 methylation pattern in T. brucei.
HostingRepository	MassIVE
AnnounceDate	2023-01-23
AnnouncementXML	Submission_2023-01-23_09:22:36.921.xml
DigitalObjectIdentifier
ReviewLevel	Non peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Supported dataset by repository
PrimarySubmitter	Yixuan Xie
SpeciesList	scientific name: Trypanosoma brucei; NCBI TaxID: 5691;
ModificationList	Dimethyl; Methyl; Trimethyl
Instrument	Q Exactive Plus

Revision	Datetime	Status	ChangeLog Entry
0	2022-11-09 10:40:32	ID requested
⏵ 1	2023-01-23 09:22:37	announced

no publication

submitter keyword: DOT1A histone H3K76

Benjamin A. Garcia
contact affiliation	Department of Biochemistry and Biophysics, University of Pennsylvania
contact email	bgarci@mail.med.upenn.edu
lab head
Yixuan Xie
contact affiliation	Washington University School of Medicine in St. Louis
contact email	axexie@wustl.edu
dataset submitter

MassIVE dataset URI

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