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Cysteine oxidation as a regulatory mechanism of Arabidopsis plastidial NAD-dependent malate dehydrogenase

ABSTRACT: Malate dehydrogenases (MDHs) catalyze a reversible NAD(P)-dependent-oxidoreductase reaction that plays an important role in central metabolism and redox homeostasis of plant cells. Recent studies suggest a moonlighting function of plastidial NAD-dependent MDH (plNAD-MDH) in plastid biogenesis, independent of its enzyme activity. Since plNAD-MDH has been known to be constitutively active, we aimed to clarify if an inactive plNAD-MDH could occur in vivo. In this study, redox-effects on activity and conformation of recombinant plNAD-MDH from Arabidopsis were investigated. We show that reduced plNAD-MDH is active, while it is inhibited upon oxidation. Interestingly, the presence of its cofactors NAD+ and NADH could prevent oxidative inhibition of plNAD-MDH. In addition, a conformational change upon oxidation could be observed via non-reducing SDS-PAGE. Both effects, its inhibition and conformational change, were reversible by re-reduction. Further investigation of single cysteine substitutions and mass spectrometry revealed that oxidation of plNAD-MDH leads to oxidation of all four cysteine residues. However, cysteine oxidation of C129 leads to inhibition of plNAD-MDH activity and oxidation of C147 induces its conformational change. In contrast, oxidation of C190 and C333 do not affect plNAD-MDH activity or structure, respectively. Taken together, our results demonstrate that plNAD-MDH activity can be reversibly inhibited, but not inactivated, by cysteine oxidation and might be co-regulated by the availability of its cofactors in vivo.

ORGANISM(S): Escherichia Coli

SUBMITTER: Iris Finkemeier

PROVIDER: PXD048384 | JPOST Repository | Mon Apr 29 00:00:00 BST 2024

REPOSITORIES: jPOST

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			Action	DRS
	230505_C23_013_OE480_PTM_Rev01_%2323_014_JES_a_PAP23_092.raw	Raw
	230505_C23_013_OE480_PTM_Rev01_%2323_014_JES_a_PAP23_093.raw	Raw
	230505_C23_013_OE480_PTM_Rev01_%2323_014_JES_a_PAP23_094.raw	Raw
	230505_C23_013_OE480_PTM_Rev01_%2323_014_JES_a_PAP23_095.raw	Raw
	230505_C23_013_OE480_PTM_Rev01_%2323_014_JES_a_PAP23_096.raw	Raw

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Cysteine oxidation as a regulatory mechanism of Arabidopsis plastidial NAD-dependent malate dehydrogenase

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