STRUCTURAL ANALYSIS OF HUMAN MAIM PROTEIN

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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. We aim to determine the structure of a human muscle-specific protein containing a Myosin Activation-Interaction Motif (MAIM), a domain with no identifiable sequence similarity to proteins of known structure. The 103 kDa protein has been expressed and purified from E. coli as a soluble active protein. We have generated crystals of both native and SeMet-substituted protein. We have collected complete datasets from native crystals to 2.8 [CAPITAL_A_RING] resolution on our home source (Rigaku MicroMax007 with VariMax HR confocal optics) with good statistics. The data index in a hexagonal spacegroup (a = b = 109.2 [CAPITAL_A_RING], c = 153.7 [CAPITAL_A_RING], [SMALL_ALPHA = [SMALL_BETA] = 90˚, [SMALL_GAMMA] = 120˚) with one molecule in the asymmetric unit and a solvent content of 26%, consistent with the strong diffraction we obtain from relatively small crystals. The SeMet-substituted crystals have diffraction properties analogous to the native crystals, but have been grown to larger size. Crystals have been grown in cryo-ready conditions, frozen, and stored in liquid nitrogen. We wish to collect a complete MAD dataset from SeMet-substituted crystals (22 Met/103 kDa) for solving the phase problem by MAD or SAD methods. Additionally, we will collect a high resolution