Nucleotide sequence of aceK, the gene encoding isocitrate dehydrogenase kinase/phosphatase.
In Escherichia coli, the phosphorylation and dephosphorylation of isocitrate dehydrogenase (IDH) are catalyzed by a bifunctional protein kinase/phosphatase. We have determined the nucleotide sequence of aceK, the gene encoding IDH kinase/phosphatase. This gene consists of a single open reading frame of 1,734 base pairs preceded by a Shine-Dalgarno ribosome-binding site. Examination of the deduced amino acid sequence of IDH kinase/phosphatase revealed sequences which are similar to the consensus sequence for ATP-binding sites. This protein did not, however, exhibit the extensive sequence homologies which are typical of other protein kinases. Multiple copies of the REP family of repetitive extragenic elements were found within the intergenic region between aceA (encoding isocitrate lyase) and aceK. These elements have the potential for combining to form an exceptionally stable stem-loop structure (delta G = -54 kcal/mol [ca. -226 kJ/mol]) in the mRNA. This structure, which masks the ribosome-binding site and start codon for aceK, may contribute to the downshift in expression observed between aceA and aceK. Another potential stem-loop structure (delta G = -29 kcal/mol [ca. 121 kJ/mol]), unrelated to the REP sequences, was found within aceK.
Klumpp
D J
DJ
Department of Biochemistry, University of Minnesota, Minneapolis 55455.
Plank
D W
DW
Bowdin
L J
LJ
Stueland
C S
CS
Chung
T
T
LaPorte
D C
DC
D000595:Amino Acid Sequence; D001483:Base Sequence; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases
D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; C042301:isocitrate dehydrogenase kinase; C042300:isocitrate dehydrogenase phosphatase; D010749:Phosphoprotein Phosphatases