STRUCTURAL STUDIES OF THE ELONGATOR COMPLEX

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Classical approaches identifying secretory components have identified proteins that are essential or supportive of membrane traffic. However, the yeast cytoplasmic, Elongator (Elp) complex differs from most established players, in that it negatively regulates secretion [1]. While perhaps not essential, a negative regulator can tie secretion to other processes in the cell. The Elp complex is composed of six-subunits that can be biochemically separated into two subcomplexes (Elp1/2/3p and Elp4/5/6p). The complex has been shown to have in vitro lysine acetyltransferase activity that is dependent on both subcomplexes, and is important for its ability to regulate late secretion. While the Elp1-3p subcomplex has clear structural motifs that suggest scaffolding and enzymatic functions, Elp4-6p's role remains unknown. A structure of the Elp4/5/6p complex will provide insight into the function and evolution of the Elp complex. Prior diffraction experiments at CHESS should crystals could diffract to 3.5A, but large unit cell, high mosaicity (1-1.5) and fused crystals complicated data collection. During screening proteolysis of samples yielded crystals with significantly improved diffraction to 2.4A. New constructs based on this proteolysis give crystals in similar conditions and are being tested for their diffraction quality. [1] Rahl PB, Chen CZ, Collins RN (2005) Elp1p, the yeast homolog of the FD disease syndrome protein, negatively regulates exocytosis independently of transcriptional elongation. Mol Cell 17: 841-853.