title: Selenocysteine synthase from Escherichia coli. Nucleotide sequence of the gene (selA) and purification of the protein.
abstract: The nucleotide sequence of the selA gene from Escherichia coli whose product is involved in the conversion of seryl-tRNA(Sec UCA) into selenocysteyl-tRNA(Sec UCA) was determined. selA codes for a polypeptide of a calculated Mr of 50,667; a protein of appropriate size was synthesized in vivo in a T7 promoter/polymerase system. An assay for SELA activity was devised which is based on the seryl-tRNA(Sec UCA)-dependent incorporation of [75Se] selenium into acid-insoluble material. It was used to follow SELA purification from cells that overproduced the protein from a phage T7 promoter plasmid. Purified native SELA protein migrates in gel filtration experiments with a native Mr of about 600,000. SELA contains 1 mol of bound pyridoxal 5-phosphate/mol of 50-kDa subunit. Evidence is presented that the overall conversion of seryl-tRNA(Sec UCA) to selenocysteyl-tRNA(Sec UCA) occurs at the SELA protein. SELA, therefore, has the function of a selenocysteine synthase.
authors.affiliation: Lehrstuhl für Mikrobiologie, Universität München, Federal Republic of Germany.
authors.forename: K
authors.initials: K
authors.lastname: Forchhammer
authors.forename: W
authors.initials: W
authors.lastname: Leinfelder
authors.forename: K
authors.initials: K
authors.lastname: Boesmiller
authors.forename: B
authors.initials: B
authors.lastname: Veprek
authors.forename: A
authors.initials: A
authors.lastname: Böck
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002853:Chromatography, Liquid; D002942:Circular Dichroism; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011732:Pyridoxal Phosphate / Q000032:analysis; D012343:RNA, Transfer / Q000235:genetics; D015183:Restriction Mapping; D013056:Spectrophotometry, Ultraviolet; D014166:Transferases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D011732:Pyridoxal Phosphate; D012343:RNA, Transfer; D014166:Transferases; C060600:selenium transferase