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- Title
The bacterial-type phosphoenolpyruvate carboxylase isozyme from developing castor oil seeds is subject to in vivo regulatory phosphorylation at serine-451
- Authors
Dalziel, Katie J.; O’Leary, Brendan; Brikis, Carolyne; Rao, Srinath K.; She, Yi-Min; Cyr, Terry; Plaxton, William C.
- Abstract
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.
- Subjects
PYRUVATE kinase; CASTOR oil; PHOSPHORYLATION; CARBOHYDRATE metabolism; IMMUNOBLOTTING; REVERSE transcriptase polymerase chain reaction
- Publication
FEBS Letters, 2012, Vol 586, Issue 7, p1049
- ISSN
0014-5793
- Publication type
Article
- DOI
10.1016/j.febslet.2012.02.054