Serine acetyltransferase from Arabidopsis thaliana can functionally complement the cysteine requirement of a cysE mutant strain of Escherichia coli.
Serine acetyltransferase, a key enzyme in the L-cysteine biosynthetic pathway of sulfate assimilating organisms, catalyzes the formation of O-acetylserine, the immediate precursor of L-cysteine. In higher plants, it is thought that sulfur assimilation occurs primarily in leaf chloroplasts; however, serine acetyltransferase is not localized exclusively in this tissue and organelle. At least three genes for serine acetyltransferase have been identified in the higher plant Arabidopsis thaliana. Reported here is a cDNA corresponding to one of these genes, SAT1, a 1,079 bp clone with an open reading frame predicted to encode a 34-kDa protein that is able to functionally complement a serine acetyltransferase mutant strain of Escherichia coli. The predicted amino acid sequence of SAT1 shows significant homology with bacterial serine acetyltransferases. SAT1, expressed as a recombinant protein, shows serine acetyltransferase enzyme activity and cross-reacts with an antibody against the homologous E. coli enzyme. The first 40 amino acids of the SAT1 polypeptide resembles a plastid transit peptide, but the polypeptide is probably not plastid localized. Genomic DNA blot analysis of A. thaliana showed that SAT1 is a single copy gene and RNA blot analysis revealed that SAT1 is expressed in both leaves and roots.
Murillo
M
M
Department of Plant Science Rutgers University, New Brunswick, NJ 08903, USA.
Foglia
R
R
Diller
A
A
Lee
S
S
Leustek
T
T
D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003545:Cysteine / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D018628:Gene Dosage; D015870:Gene Expression; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D012333:RNA, Messenger / Q000032:analysis; D018749:RNA, Plant / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D051050:Serine O-Acetyltransferase
D001426:Bacterial Proteins; D018076:DNA, Complementary; D018744:DNA, Plant; D029968:Escherichia coli Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; D000123:Acetyltransferases; C070785:CysE protein, E coli; D051050:Serine O-Acetyltransferase; D003545:Cysteine