title: Molecular characterization of the alpha-subunit of Trichomonas vaginalis hydrogenosomal succinyl CoA synthetase.
abstract: The anaerobic, parasitic protist, Trichomonas vaginalis, is characterized by the absence of mitochondria and the presence of double membrane bound organelles called hydrogenosomes. Succinyl-coenzyme A synthetase is a hydrogenosomal enzyme which catalyzes the formation of ATP via substrate-level phosphorylation. We have characterized genes encoding the alpha subunit of the hydrogenosomal protein succinyl-coenzyme A synthetase (SCS). The alpha-SCS of T. vaginalis is encoded by a multigene family composed of 3 similar genes that do not appear allelic. These 3 alpha-SCS genes encode a protein with a calculated molecular mass of approximately 32.5 kDa that has > 50% identity (> 70% similarity with alpha-SCSs from Escherichia coli, Thermus flavus, and rat liver mitochondria. Antibodies raised against recombinant T vaginalis alpha-SCS expressed in bacteria were used to isolate alpha-SCS proteins from purified hydrogenosomes. These proteins partition into the soluble fraction of hydrogenosomes treated with sodium carbonate at high pH, consistent with a matrix localization in the organelle. Amino-terminal sequencing of purified alpha-SCS proteins shows that mature proteins lack a short, leader sequence of 9 amino acids. These amino terminal sequences which are cleaved from T. vaginalis alpha-SCSs are similar to each other and to all other leader sequences identifed on hydrogenosomal proteins.
authors: Department of Microbiology and Immunology, University of California, Los Angeles, 90024-1747.
authors: C J
authors: CJ
authors: Lahti
authors: P J
authors: PJ
authors: Bradley
authors: P J
authors: PJ
authors: Johnson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D015388:Organelles / Q000201:enzymology; D011487:Protein Conformation; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013389:Succinate-CoA Ligases / Q000737:chemistry / Q000235:genetics*; D013824:Thermus / Q000201:enzymology / Q000235:genetics; D014246:Trichomonas vaginalis / Q000201:enzymology* / Q000235:genetics*
chemical_list: D017931:DNA Primers; D016054:DNA, Protozoan; D013389:Succinate-CoA Ligases