Identification and Functional Characterization of Protest SWI/SNF and ISWI Complexes

The thesis aims to identify and initiate functional characterization of the SWI/SNF and ISWI complexes in Tetrahymena thermophila. Through affinity purification of the conserved subunit Snf5 followed by mass spectrometry (AP-MS), I identified the first SWI/SNF complex in protists. One of the subunits I found is a small bromodomain containing protein named Ibd1. Through AP-MS of Ibd1 I found Ibd1 is versatile and interacts with several additional chromatin remodeling complexes. Bromodomains are known to have affinity for acetylated lysine residues within proteins such as histones. A peptide array experiment suggests that Ibd1 also has affinity for acetylated chromatin. Indirect immunofluorescence (IF) of Ibd1 hints at a role in transcription. My analysis of Tetrahymena Iswi1 shows expression during meiosis, vegetative growth and starvation. IF data shows its localization is consistent with Iswi1 function in mitosis/meiosis or maintenance of silent chromatin. AP-MS of ISW1 discovered several interacting proteins of unknown function.