The bacterial-type phosphoenolpyruvate carboxylase isozyme from developing castor oil seeds is subject to in vivo regulatory phosphorylation at serine-451

FEBS Letters
Katie J DalzielW C Plaxton

Abstract

Phosphoenolpyruvate carboxylase (PEPC) is a tightly controlled anaplerotic enzyme situated at a pivotal branch point of plant carbohydrate-metabolism. In developing castor oil seeds (COS) a novel allosterically-densensitized 910-kDa Class-2 PEPC hetero-octameric complex arises from a tight interaction between 107-kDa plant-type PEPC and 118-kDa bacterial-type PEPC (BTPC) subunits. Mass spectrometry and immunoblotting with anti-phosphoSer451 specific antibodies established that COS BTPC is in vivo phosphorylated at Ser451, a highly conserved target residue that occurs within an intrinsically disordered region. This phosphorylation was enhanced during COS development or in response to depodding. Kinetic characterization of a phosphomimetic (S451D) mutant indicated that Ser451 phosphorylation inhibits the catalytic activity of BTPC subunits within the Class-2 PEPC complex.

References

Feb 24, 2005·Annual Review of Plant Biology·Katsura IzuiYasushi Kai
Dec 17, 2009·Annals of Botany·Sandra J HeyNigel G Halford
Mar 6, 2010·The Journal of Neuroscience : the Official Journal of the Society for Neuroscience·Katerina E PaleologouHilal A Lashuel
May 26, 2012·Frontiers in Neuroinformatics·Allan Mackenzie-Graham

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