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This article is part of the supplement: Proceedings of the 2007 and 2008 Symposia on Protein N-terminal Acetylation

Open Access Proceedings

Characterization of the human Nα-terminal acetyltransferase B enzymatic complex

Amagoia Ametzazurra123, Cristina Gázquez1, Marta Lasa1, Esther Larrea1, Jesús Prieto12 and Rafael Aldabe1*

Author Affiliations

1 Division of Hepatology and Gene Therapy, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain

2 Liver Unit, Clínica Universitaria, CIBER-EHD, Pamplona, Spain

3 Proteomika, S.L. Parque Tecnológico de Zamudio. Edificio 504. 48160 Derio, Spain

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BMC Proceedings 2009, 3(Suppl 6):S4  doi:10.1186/1753-6561-3-S6-S4

Published: 4 August 2009

Abstract

Background

Human Nα-acetyltransferase complex B (hNatB) is integrated by hNaa20p (hNAT5/hNAT3) and hNaa25p (hMDM20) proteins. Previous data have shown that this enzymatic complex is implicated in cell cycle progression and carcinogenesis. In yeast this enzyme acetylates peptides composed by methionine and aspartic acid or glutamic acid in their first two positions respectively and it has been shown the same specificity in human cells.

Methods

We have silenced hNAA20 expression in hepatic cell lines using recombinant adenoviruses that express specific siRNAs against this gene and analyzed cell cycle progression and apoptosis induction after this treatment. Immunopurified hNatB enzymatic complexes from human cell lines were used for analyzing hNatB in vitro enzymatic activity using as substrate peptides predicted to be acetylated by NatB.

Results

hNAA20 silencing in hepatic cell lines reduces cell proliferation in a p53 dependent and independent manner. At the same time this treatment sensitizes the cells to a proapototic stimulus. We have observed that the hNatB complex isolated from human cell lines can acetylate in vitro peptides that present an aspartic or glutamic acid in their second position as has been described in yeast.

Conclusion

hNatB enzymatic complex is implicated in cell cycle progression but it exerts its effects through different mechanisms depending on the cellular characteristics. This is achievable because it can acetylate a great number of peptides composed by an aspartic or glutamic acid at their second residue and therefore it can regulate the activity of a great number of proteins.