Abstract
Paramecium bursaria chlorella virus 1 (PBCV-1), a large DNA virus that infects green algae, encodes a histone H3 lysine 27-specific methyltransferase that functions in global transcriptional silencing of the host. PBCV-1 has another gene a654l that encodes a protein with sequence similarity to the GCN5 family histone acetyltransferases. In this study, we report a 1.5 Å crystal structure of PBCV-1 A654L in a complex with coenzyme A. The structure reveals a unique feature of A654L that precludes its acetylation of histone peptide substrates. We demonstrate that A654L, hence named viral polyamine acetyltransferase (vPAT), acetylates polyamines such as putrescine, spermidine, cadaverine, and homospermidine present in both PBCV-1 and its host through a reaction dependent upon a conserved glutamate 27. Our study suggests that as the first virally encoded polyamine acetyltransferase, vPAT plays a possible key role in the regulation of polyamine catabolism in the host during viral replication.
Highlights
Paramecium bursaria chlorella virus 1 (PBCV-1) gene a654l encodes a protein with sequence similarity to GCN5 histone acetyltransferases
PBCV-1 has another gene a654l that encodes a protein with sequence similarity to the GCN5 family histone acetyltransferases
We demonstrate that A654L, named viral polyamine acetyltransferase, acetylates polyamines such as putrescine, spermidine, cadaverine, and homospermidine present in both PBCV-1 and its host through a reaction dependent upon a conserved glutamate 27
Summary
PBCV-1 gene a654l encodes a protein with sequence similarity to GCN5 histone acetyltransferases. Results: A crystal structure of A654L bound to coenzyme A reveals how A654L acetylates polyamines, not histone lysines. Paramecium bursaria chlorella virus 1 (PBCV-1), a large DNA virus that infects green algae, encodes a histone H3 lysine 27-specific methyltransferase that functions in global transcriptional silencing of the host. Our study suggests that as the first virally encoded polyamine acetyltransferase, vPAT plays a possible key role in the regulation of polyamine catabolism in the host during viral replication. The PBCV-1 genome has a gene, a654l, that encodes a protein with sequence similarity to the GCN5 family of histone acetyltransferases (HATs) that are known for their role in chromatin remodeling and gene transcriptional activation through hyperacetylation of histone lysines [10, 11]. To understand the structure and function of A654L, in this study, we determined a 1.5 Å resolution crystal structure of A654L bound to CoA and discovered and performed structure-guided characterization of the acetyl transfer reaction of A654L with an unexpected class of substrates
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