Pyrroline-5-carboxylate metabolism protein complex detected in Arabidopsis thaliana leaf mitochondria

authored by

Yao Zheng, Cécile Cabassa-Hourton, Holger Eubel, Guillaume Chevreux, Laurent Lignieres, Emilie Crilat, Hans-Peter Braun, Sandrine Lebreton, Arnould Savouré

Abstract

Proline dehydrogenase (ProDH) and pyrroline-5-carboxylate (P5C) dehydrogenase (P5CDH) catalyze the oxidation of proline into glutamate via the intermediates P5C and glutamate-semialdehyde (GSA), which spontaneously interconvert. P5C and GSA are also intermediates in the production of glutamate from ornithine and α-ketoglutarate catalyzed by ornithine δ-aminotransferase (OAT). ProDH and P5CDH form a fused bifunctional PutA enzyme in Gram-negative bacteria and are associated in a bifunctional substrate channelling complex in Thermus thermophilus, but the physical proximity of ProDH and P5CDH in eukaryotes has not been described. Here we report evidence of physical proximity and interactions between Arabidopsis ProDH, P5CDH and OAT in the mitochondria of plants during dark-induced leaf senescence when all three enzymes are expressed. Pairwise interactions and localization of the three enzymes were investigated using bimolecular fluorescence complementation (BiFC) with confocal microscopy in tobacco and sub-mitochondrial fractionation in Arabidopsis. Evidence for a complex composed of ProDH, P5CDH, and OAT was revealed by co-migration of the proteins in native conditions upon gel electrophoresis. Co-immunoprecipitation coupled with mass spectrometry analysis confirmed the presence of the P5C metabolism complex in Arabidopsis. Pull-down assays further demonstrated a direct interaction between ProDH1 and P5CDH. P5C metabolism complexes may channel P5C among the constituent enzymes and directly provide electrons to the respiratory electron chain via ProDH.

Organisation(s)

Institute of Plant Genetics

External Organisation(s)

Institute of Ecology and Environmental Sciences of Paris (iEES)
Université Paris Cité
Sorbonne Université

Type

Article

Journal

Journal of experimental botany

Volume

75

Pages

917-934

No. of pages

18

ISSN

0022-0957

Publication date

02.02.2024

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Physiology, Plant Science

Electronic version(s)

https://doi.org/10.1093/jxb/erad406 (Access: Closed)