title: Tryptophan synthase from Agrobacterium tumefaciens 8628: isolation and properties.
abstract: Tryptophan synthase was isolated from a highly virulent strain of Agrobacterium tumefaciens 8628 (octopine type). Separation of tryptophan synthase from thermolabile protease was accomplished using fractionation with polyethylene glycol-6000 followed by ion-exchange chromatography with a pH gradient. Molecular weights of alpha- and beta-subunits are 33 and 51 kD, respectively. The tryptophan synthase is stable at 60 degrees C because of heat-tolerance beta-subunits. After heating the activity of tryptophan synthase increased up to 20 times while temperature-labile proteases lost their activities. Reaction with antibodies showed the presence of four protein bands, one of which was coeluted with nucleic acids during ion-exchange chromatography. It is suggested that the basic tryptophan synthase is encoded by trp genes in a plasmid and its role is to provide the precursor with the prokaryotic pathway of indole-3-acetic acid biosynthesis, which determines the virulence of A. tumefaciens. There is perhaps a cooperation between iaaM, iaaH, and trp genes in the plasmid during plant cell transformation.
authors.affiliation: Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia. root@sifibr.irkutsk.su
authors.forename: N I
authors.initials: NI
authors.lastname: Rekoslavskaya
authors.forename: E V
authors.initials: EV
authors.lastname: Kuznetsova
authors.forename: E F
authors.initials: EF
authors.lastname: Vysotskaya
authors.forename: R K
authors.initials: RK
authors.lastname: Salyaev
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology; D002852:Chromatography, Ion Exchange; D004795:Enzyme Stability; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007210:Indoleacetic Acids / Q000378:metabolism; D008970:Molecular Weight; D010941:Plant Tumors / Q000382:microbiology; D010944:Plants / Q000382:microbiology; D012231:Rhizobium / Q000201:enzymology* / Q000472:pathogenicity; D013696:Temperature; D014367:Tryptophan Synthase / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D014774:Virulence
chemical_list: D000907:Antibodies, Bacterial; D007210:Indoleacetic Acids; C030737:indoleacetic acid; D014367:Tryptophan Synthase