Substrate and Functional Diversity of Lysine Acetylation Revealed by a Proteomics Survey
ABSTRACT Acetylation of proteins on lysine residues is a dynamic posttranslational modification that is known to play a key role in regulating transcription and other DNA-dependent nuclear processes. However, the extent of this modification in diverse cellular proteins remains largely unknown, presenting a major bottleneck for lysine-acetylation biology. Here we report the first proteomic survey of this modification, identifying 388 acetylation sites in 195 proteins among proteins derived from HeLa cells and mouse liver mitochondria. In addition to regulators of chromatin-based cellular processes, nonnuclear localized proteins with diverse functions were identified. Most strikingly, acetyllysine was found in more than 20% of mitochondrial proteins, including many longevity regulators and metabolism enzymes. Our study reveals previously unappreciated roles for lysine acetylation in the regulation of diverse cellular pathways outside of the nucleus. The combined data sets offer a rich source for further characterization of the contribution of this modification to cellular physiology and human diseases.
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ABSTRACT: Malnutrition during the fetal growth period increases risk for later obesity and type 2 diabetes mellitus (T2DM). We have shown that a prenatal low protein (8% protein; LP) diet followed by postnatal high fat (45% fat; HF) diet results in offspring propensity for adipose tissue catch-up growth, obesity and T2DM in Sprague–Dawley rats. Skeletal muscle is the major tissue for insulin-mediated glucose uptake. Dysfunctional skeletal muscle mitochondrial function, particularly reduction in expression of mitochondrial protein sirtuin protein 3 (Sirt3) contributes to development of T2DM by reducing mitochondrial respiration. Therefore, we hypothesized that maternal LP and postnatal HF diet would increase T2DM risk due Sirt3 dysfunction within skeletal muscle mitochondria. Using our maternal LP and postnatal HF diet model, we showed that skeletal muscle mitochondrial oxygen consumption rate (OCR) was decreased by maternal LP diet. Mitochondria copy number, mitochondrial thermogenesis (UCP-1) expression, and mitochondrial biogenic factors including nuclear respiratory factor 1 (NRF1) and cytochrome c oxidase 1 and 4 (COX-1 and 4) were unaffected by maternal LP and postnatal HF diets. Skeletal muscle Sirt3 mRNA decreased with maternal LP diet. A mitochondrial substrate of Sirt3, succinate dehydrogenase (SDH), is regulated by Sirt3 via lysine residue acetylation status of SDH. Acetylated SDH protein (inactive form) levels were moderately decreased by maternal LP diet. Taken together these data suggest that maternal LP and postnatal HF diets may increase the risk for T2D by decreasing skeletal muscle oxidative respiration via increased Sirt3 and possibly by decreased amounts of the active form of SDH enzyme.The Journal of Nutritional Biochemistry 11/2014; 26(2). DOI:10.1016/j.jnutbio.2014.10.003 · 4.59 Impact Factor
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ABSTRACT: The control of chromosome segregation relies on the spindle assembly checkpoint (SAC), a complex regulatory system that ensures the high fidelity of chromosome segregation in higher organisms by delaying the onset of anaphase until each chromosome is properly hi-oriented on the mitotic spindle. Central to this process is the establishment of multiple yet specific protein-protein interactions in a narrow time-space window. Here we discuss the highly dynamic nature of multi-protein complexes that control chromosome segregation in which an intricate network of weak but cooperative interactions modulate signal amplification to ensure a proper SAC response. We also discuss the current structural understanding of the communication between the SAC and the kinetochore; how transient interactions can regulate the assembly and disassembly of the SAC as well as the challenges and opportunities for the definition and the manipulation of the flow of information in SAC signaling.Frontiers in Physiology 09/2014; 5:1-11. DOI:10.3389/fphys.2014.00368 · 3.50 Impact Factor
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ABSTRACT: Lysine modifications have been studied extensively in the nucleus, where they play pivotal roles in gene regulation and constitute one of the pillars of epigenetics. In the cytoplasm, they are critical to proteostasis. However, in the last decade we have also witnessed the emergence of mitochondria as a prime locus for post-translational modification (PTM) of lysine thanks, in large measure, to evolving proteomic techniques. Here, we review recent work on evolving set of PTM that arise from the direct reaction of lysine residues with energized metabolic thioester-coenzyme A intermediates, including acetylation, succinylation, malonylation, and glutarylation. We highlight the evolutionary conservation, kinetics, stoichiometry, and cross-talk between members of this emerging family of PTMs. We examine the impact on target protein function and regulation by mitochondrial sirtuins. Finally, we spotlight work in the heart and cardiac mitochondria, and consider the roles acetylation and other newly-found modifications may play in heart disease.Frontiers in Physiology 09/2014; 5:301. DOI:10.3389/fphys.2014.00301 · 3.50 Impact Factor