MRPS36 provides a missing link in the eukaryotic 2-oxoglutarate dehydrogenase complex for recruitment of E3 to the E2 core - Phospoproteomics data

ABSTRACT: The tricarboxylic acid (TCA) cycle, or Krebs cycle, is the central pathway of energy production in eukaryotic cells and plays a key part in aerobic respiration throughout all kingdoms of life. The enzymes involved in this cycle generate the reducing equivalents NADH and FADH2 by a series of enzymatic reactions, which are utilized by the electron transport chain to produce ATP. One of the key enzymes in this cycle is 2-oxoglutarate dehydrogenase (OGDHC), which generates NADH by oxidative decarboxylation of 2-oxoglutarate to succinyl-CoA. Notably, this enzyme consists of multiple subunits as a megadalton protein complex. Thus far, it was thought that OGDHC consists of solely three catalytically active subunits (E1, E2, E3). However in fungi and animals, the small protein MRPS36 has been proposed as a putative additional component. Based on extensive XL-MS data obtained from measurements in both, mice and bovine heart mitochondria, and from phylogenetic analyses, we provide structural evidence that MRPS36 is an exclusive and crucial member of eukaryotic OGDHC. Comparative genomics analysis and computational structure predictions reveal that in eukaryotic OGDHC, E2o does not contain a peripheral subunit-binding (PSBD) domain. Instead, our data provide compelling evidence that in eukaryotes, MRPS36 evolved as E3 adaptor protein, functionally replacing the PSBD domain. Based on our data we provide a refined structural model of the complete eukaryotic OGDHC assembly containing all its 58 subunits (~ 3.4 MDa). The model provides new insights into the protein-protein interactions within the OGDH complex and highlights putative mechanistic implications.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Bos Taurus (bovine)

TISSUE(S): Heart

SUBMITTER: Johannes Hevler  

LAB HEAD: Albert Heck

PROVIDER: PXD036896 | Pride | 2023-03-10

REPOSITORIES: Pride