EFFECTS OF TOM20 AND TOM22 ON THE STRUCTURE OF PROTEINS

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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. This subproject (SPID 0018) is no longer active. Dr. Engen has graduated from the NM-INBRE after receiving an R01 grant. Conformational changes associated with protein import into mitochondria are being investigated. Understanding the individual interactions during import will increase our understanding of this fundamental cellular process. Hydrogen exchange (HX) and high-resolution mass spectrometry (MS) methods are being used to observe the incorporation of deuterium into proteins in the presence of proteins that initially receive the protein that is to be imported into mitochondria. In this reporting period, one protein from the transporter of the outer membrane complex (Tom20) was incuabted with a test protein (DHFR) and HX MS analysis were carried out. The results indicate that Tom20 is capable of disrupting the dynamics and/or conformation of test proteins, perhaps in a mechanism designed to make unfolding easier during importation. To characterize the interaction of the test protein with live, import-competent mitochondria, mass spectrometry methods were developed. The results indicate that the outer surface of mitochondria binds quite non-specifically to proteins. We were unsuccessful in overcoming this experimental difficulty but feel that inclusion of MS friendly detergents may be a solution.