URF13, a maize mitochondrial pore-forming protein, is oligomeric and has a mixed orientation in Escherichia coli plasma membranes

• Published in: Proceedings of the National Academy of Sciences - PNAS 1991-12, Vol.88 (23), p.10865-10869
• Main Authors: Korth, K.L. (North Carolina State University, Raleigh, NC), Kaspi, C.I, Siedow, J.N, Levings, C.S. III
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Antibodies; Biological and medical sciences; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cell membranes; Cloning, Molecular; COCHLIOBOLUS; Corn; Cross-Linking Reagents - metabolism; ESCHERICHIA; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; ESTERILIDAD MASCULINA CITOPLASMICA; ESTRUCTURA CELULAR; Fundamental and applied biological sciences. Psychology; Immunoblotting; Intracellular Membranes - metabolism; Intracellular Membranes - ultrastructure; Macromolecular Substances; Miscellaneous; Mitochondria; Mitochondria - metabolism; Mitochondria - ultrastructure; Mitochondrial membranes; Mitochondrial Proteins; MITOCHONDRIE; MITOCONDRIA; Models, Structural; Molecular Sequence Data; MYCOSPHAERELLA; P branes; Plant Proteins - genetics; Plant Proteins - isolation & purification; Plant Proteins - metabolism; plasma membranes; Plasmids; Protein Conformation; PROTEINAS; PROTEINE; Proteins; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Spheroplasts; STERILITE MALE CYTOPLASMIQUE; STRUCTURE CELLULAIRE; Topology; Toxins; ZEA MAYS; Zea mays - genetics; Zea mays - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.23.10865

URF13, an inner mitochondrial membrane protein of the maize Texas male-sterile cytoplasm (cms-T), has one orientation in the inner membrane of maize mitochondria but two topological orientations in the plasma membrane when expressed in Escherichia coli. Antibodies specific for the carboxyl terminus of URF13 and for an amino-terminal tag fused to URF13 in E. coli were used to determine the location of each end of the protein following protease treatments of right-side-out and inside-out vesicles derived from cms-T mitochondria and the E. coli plasma membrane. Cross-linking studies indicate that a portion of the URF13 population in mitochondria and E. coli exists in membranes in an oligomeric state and, in combination with proteolysis studies, show that individual subunits within a given multimer have the same orientation. A three-membrane-spanning helical model for URF13 topology is presented.