Phylogenetic analysis of the SAP30 family of transcriptional regulators reveals functional divergence in the domain that binds the nuclear matrix.
BACKGROUND
Deacetylation of histones plays a fundamental role in gene silencing, and this is mediated by a corepressor complex containing Sin3 as an essential scaffold protein. In this report we examine the evolution of two proteins in this complex, the Sin3-associated proteins SAP30L and SAP30, by using an archive of protein sequences from 62 species.


RESULTS
Our analysis indicates that in tetrapods SAP30L is more similar than SAP30 to the ancestral protein, and the two copies in this group originated by gene duplication which occurred after the divergence of Actinopterygii and Sarcopterygii about 450 million years ago (Mya). The phylogenetic analysis and biochemical experiments suggest that SAP30 has diverged functionally from the ancestral SAP30L by accumulating mutations that have caused attenuation of one of the original functions, association with the nuclear matrix. This function is mediated by a nuclear matrix association sequence, which consists of a conserved motif in the C-terminus and the adjacent nucleolar localization signal (NoLS).


CONCLUSIONS
These results add further insight into the evolution and function of proteins of the SAP30 family, which share many characteristic with nuclear scaffolding proteins that are intimately involved in regulation of gene expression. Furthermore, SAP30L seems essential to eukaryotic biology, as it is found in animals, plants, fungi, as well as some taxa of unicellular eukaryotes.
Viiri
Keijo M
KM
Paediatric Research Centre, University of Tampere Medical School and Tampere University Hospital, 33520 Tampere, Finland. keijo.viiri@uta.fi
Heinonen
Taisto Y K
TY
Mäki
Markku
M
Lohi
Olli
O
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D017124:Conserved Sequence; D019143:Evolution, Molecular; D020440:Gene Duplication; D006367:HeLa Cells; D006655:Histone Deacetylases / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015530:Nuclear Matrix / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D010802:Phylogeny; D054730:Protein Interaction Domains and Motifs; D015027:Zebrafish
D009687:Nuclear Proteins; C113294:SAP30 protein, human; C487046:SAP30L protein, human; D006655:Histone Deacetylases