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Oligomerization and characteristics of phosphoenolpyruvate carboxylase in Synechococcus PCC 7002

DOI: 10.1038/s41598-020-60249-2 DOI Help

Authors: Claudia Durall De La Fuente (Uppsala University) , Sandesh Kanchugal Puttaswamy (Uppsala University) , Maria Selmer (Uppsala University) , Peter Lindblad (Uppsala University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Scientific Reports , VOL 10

State: Published (Approved)
Published: February 2020
Diamond Proposal Number(s): 15868

Open Access Open Access

Abstract: Phosphoenolpyruvate carboxylase (PEPc) is an essential enzyme in plants. A photosynthetic form is present both as dimer and tetramer in C4 and CAM metabolism. Additionally, non-photosynthetic PEPcs are also present. The single, non-photosynthetic PEPc of the unicellular cyanobacterium Synechococcus PCC 7002 (Synechococcus), involved in the TC A cycle, was examined. Using size exclusion chromatography (SEC) and small angle X-ray scattering (SAXS), we observed that PEPc in Synechococcus exists as both a dimer and a tetramer. This is the first demonstration of two different oligomerization states of a non-photosynthetic PEPc. High concentration of Mg2+, the substrate PEP and a combination of low concentration of Mg2+ and HCO3 − induced the tetramer form of the carboxylase. Using SEC-SAXS analysis, we showed that the oligomerization state of the carboxylase is concentration dependent and that, among the available crystal structures of PEPc, the scattering profile of PEPc of Synechococcus agrees best with the structure of PEPc from Escherichia coli. In addition, the kinetics of the tetramer purified in presence of Mg2+ using SEC, and of the mixed population purified in presence of Mg2+ using a Strep-tagged column were examined. Moreover, the enzyme showed interesting allosteric regulation, being activated by succinate and inhibited by glutamine, and not affected by either malate, 2-oxoglutarate, aspartic acid or citric acid.

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: B21-High Throughput SAXS

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