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Background: 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.
Conclusion: A654L functions as a polyamine acetyltransferase.
Significance: As the first viral polyamine acetyltransferase, A654L has a possible role in host polyamine catabolism in viral replication.
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 1.5A˚ 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.
Includes Supplemental Material.