chromo barrel domain of human tat-interactive protein 60, and similar proteins
Tat-interactive protein 60 (also known as KAT5 or HTATIP) catalyzes the acetylation of lysine side chains in various histone and nonhistone proteins, and in itself. It plays roles in multiple cellular processes including remodeling, transcription, DNA double-strand break repair, apoptosis, embryonic stem cell identity, and embryonic development. The TIP60 chromo barrel domain recognizes trimethylated lysine at site 9 of histone H3 (H3K9me3) which triggers TIP60 to acetylate and activate ataxia telangiectasia-mutated kinase, thereby promoting the DSB repair pathway. In a different study, the TIP60 chromo barrel domain was shown to bind H3K4me1, which stabilizes TIP60 recruitment to a subset of estrogen receptor alpha target genes, facilitating regulation of the associated gene transcription. SH3-fold-beta-barrel domains of the chromo-like superfamily include chromodomains, chromo shadow domains, and chromo barrel domains, and are implicated in the recognition of lysine-methylated histone tails and nucleic acids. The chromodomain differs, in that it lacks the first strand of the SH3-fold-beta-barrel. This first strand is altered by insertion in the chromo shadow domains, and chromo barrel domains are typical SH3-fold-beta-barrel domains with sequence similarity to the canonical chromodomain. This subgroup belongs to the MOF-like chromo barrels may be may be auto-inhibited, i.e. they seem to have occluded peptide binding sites.
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