Mitochondrial SIRT4-type proteins in Caenorhabditis elegans and mammals interact with pyruvate carboxylase and other acetylated biotin-dependent carboxylases

Abstract

The biological and enzymatic function of SIRT4 is largely uncharacterized. We show that the C. elegans SIR-2.2 and SIR-2.3 orthologs of SIRT4 are ubiquitously expressed, also localize to mitochondria and function during oxidative stress. Further, we identified conserved interaction with mitochondrial biotin-dependent carboxylases (PC, PCC, MCCC), key enzymes in anaplerosis and ketone body formation. The carboxylases were found acetylated on multiple lysine residues and detailed analysis of mPC suggested that one of these residues, K748ac, might regulate enzymatic activity. Nevertheless, no changes in mPC acetylation levels and enzymatic activity could be detected upon overexpression or loss of functional SIRT4.

Sirtuin 4 Is a Lipoamidase Regulating Pyruvate Dehydrogenase Complex Activity

“…S1). Interaction of SIRT4 with biotin-dependent carboxylases has been reported (Wirth et al, 2013), validating the reliability of our dataset. Interestingly, we found that SIRT4 associated with all three of the multimeric mammalian dehydrogenase complexes—pyruvate dehydrogenase (PDH), oxoglutarate dehydrogenase (OGDH), and branched-chain alpha-keto acid dehydrogenase (BCKDH) (Fig.…”

SIRT4 Is a Lysine Deacylase that Controls Leucine Metabolism and Insulin Secretion

“…We and others have found that SIRT4 binds to several enzymes of the leucine oxidation pathway (Mathias et al, 2014; Wirth et al, 2013). Interestingly, our concurrent study demonstrates that reactive acyl-CoA species (RAS) have the potential to react non-enzymatically with lysine residues to generate protein modifications (Wagner et al, 2017).…”

“…4A). The methylcrotonyl-CoA carboxylase complex (MCCC) was previously shown to interact with SIRT4 and was thought to be a putative substrate of SIRT4 (Wirth et al, 2013). Importantly, the MCCC enzyme generates MGc-CoA, which can be chemically or enzymatically reduced to MG-CoA (Roe et al, 1986).…”

C. eleganssirtuin SIR-2.4 and its mammalian homolog SIRT6 in stress response

“…For example, the number of P-granules is increased in stressed and aged animals. 2,9,26,29 We have shown that the changes in size and number of P-granules were altered by growth temperature and by SIR-2.4. Furthermore, we observed that P-granules proteins (e.g., PGL-1/3 and GLH-1.2) specifically interact with SIR-2.…”

“…24,25 We have recently described the function, localization, and interactome of the mitochondrial SIR-2.2 and SIR-2.3 as well as of the nuclear SIR-2.4 ( Table 1). 26,27 As shown (Table 1), the sirtuins are an evolutionarily conserved protein family regarding their amino acid sequences, localization, and interaction partners.…”