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Das S, Singh A, Shah P. Evaluating single-cell variability in proteasomal decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554358. [PMID: 37662347 PMCID: PMC10473619 DOI: 10.1101/2023.08.22.554358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Gene expression is a stochastic process that leads to variability in mRNA and protein abundances even within an isogenic population of cells grown in the same environment. This variation, often called gene-expression noise, has typically been attributed to transcriptional and translational processes while ignoring the contributions of protein decay variability across cells. Here we estimate the single-cell protein decay rates of two degron GFPs in Saccharomyces cerevisiae using time-lapse microscopy. We find substantial cell-to-cell variability in the decay rates of the degron GFPs. We evaluate cellular features that explain the variability in the proteasomal decay and find that the amount of 20s catalytic beta subunit of the proteasome marginally explains the observed variability in the degron GFP half-lives. We propose alternate hypotheses that might explain the observed variability in the decay of the two degron GFPs. Overall, our study highlights the importance of studying the kinetics of the decay process at single-cell resolution and that decay rates vary at the single-cell level, and that the decay process is stochastic. A complex model of decay dynamics must be included when modeling stochastic gene expression to estimate gene expression noise.
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Affiliation(s)
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, Biomedical Engineering, University of Delaware
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2
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Engineering a microbial biosynthesis platform for de novo production of tropane alkaloids. Nat Commun 2019; 10:3634. [PMID: 31406117 PMCID: PMC6690885 DOI: 10.1038/s41467-019-11588-w] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 07/18/2019] [Indexed: 02/07/2023] Open
Abstract
Tropane alkaloids (TAs) are a class of phytochemicals produced by plants of the nightshade family used for treating diverse neurological disorders. Here, we demonstrate de novo production of tropine, a key intermediate in the biosynthetic pathway of medicinal TAs such as scopolamine, from simple carbon and nitrogen sources in yeast (Saccharomyces cerevisiae). Our engineered strain incorporates 15 additional genes, including 11 derived from diverse plants and bacteria, and 7 disruptions to yeast regulatory or biosynthetic proteins to produce tropine at titers of 6 mg/L. We also demonstrate the utility of our engineered yeast platform for the discovery of TA derivatives by combining biosynthetic modules from distant plant lineages to achieve de novo production of cinnamoyltropine, a non-canonical TA. Our engineered strain constitutes a starting point for future optimization efforts towards realizing industrial fermentation of medicinal TAs and a platform for the synthesis of TA derivatives with enhanced bioactivities. Tropane alkaloids (TAs) are a group of phytochemicals that are used to treat neurological disorders. Here, the authors engineer baker’s yeast to produce tropine, a key intermediate in the biosynthetic pathway of TAs, and cinnamoyltropine, a non-canonical TA, from simple carbon and nitrogen sources.
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Expression of MTAP inhibits tumor-related phenotypes in HT1080 cells via a mechanism unrelated to its enzymatic function. G3-GENES GENOMES GENETICS 2014; 5:35-44. [PMID: 25387827 PMCID: PMC4291467 DOI: 10.1534/g3.114.014555] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Methylthioadenosine Phosphorylase (MTAP) is a tumor suppressor gene that is frequently deleted in human cancers and encodes an enzyme responsible for the catabolism of the polyamine byproduct 5′deoxy-5′-methylthioadenosine (MTA). To elucidate the mechanism by which MTAP inhibits tumor formation, we have reintroduced MTAP into MTAP-deleted HT1080 fibrosarcoma cells. Expression of MTAP resulted in a variety of phenotypes, including decreased colony formation in soft-agar, decreased migration, decreased in vitro invasion, increased matrix metalloproteinase production, and reduced ability to form tumors in severe combined immunodeficiency mice. Microarray analysis showed that MTAP affected the expression of genes involved in a variety of processes, including cell adhesion, extracellular matrix interaction, and cell signaling. Treatment of MTAP-expressing cells with a potent inhibitor of MTAP’s enzymatic activity (MT-DADMe-ImmA) did not result in a MTAP− phenotype. This finding suggests that MTAP’s tumor suppressor function is not the same as its known enzymatic function. To confirm this, we introduced a catalytically inactive version of MTAP, D220A, into HT1080 cells and found that this mutant was fully capable of reversing the soft agar colony formation, migration, and matrix metalloproteinase phenotypes. Our results show that MTAP affects cellular phenotypes in HT1080 cells in a manner that is independent of its known enzymatic activity.
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Mary C, Duek P, Salleron L, Tienz P, Bumann D, Bairoch A, Lane L. Functional identification of APIP as human mtnB, a key enzyme in the methionine salvage pathway. PLoS One 2012; 7:e52877. [PMID: 23285211 PMCID: PMC3532061 DOI: 10.1371/journal.pone.0052877] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 11/22/2012] [Indexed: 02/08/2023] Open
Abstract
The methionine salvage pathway is widely distributed among some eubacteria, yeast, plants and animals and recycles the sulfur-containing metabolite 5-methylthioadenosine (MTA) to methionine. In eukaryotic cells, the methionine salvage pathway takes place in the cytosol and usually involves six enzymatic activities: MTA phosphorylase (MTAP, EC 2.4.2.28), 5′-methylthioribose-1-phosphate isomerase (mtnA, EC 5.3.1.23), 5′-methylthioribulose-1-phosphate dehydratase (mtnB, EC: 4.2.1.109), 2,3-dioxomethiopentane-1-phosphate enolase/phosphatase (mtnC, EC 3.1.3.77), aci-reductone dioxygenase (mtnD, EC 1.13.11.54) and 4-methylthio-2-oxo-butanoate (MTOB) transaminase (EC 2.6.1.-). The aim of this study was to complete the available information on the methionine salvage pathway in human by identifying the enzyme responsible for the dehydratase step. Using a bioinformatics approach, we propose that a protein called APIP could perform this role. The involvement of this protein in the methionine salvage pathway was investigated directly in HeLa cells by transient and stable short hairpin RNA interference. We show that APIP depletion specifically impaired the capacity of cells to grow in media where methionine is replaced by MTA. Using a Shigella mutant auxotroph for methionine, we confirm that the knockdown of APIP specifically affects the recycling of methionine. We also show that mutation of three potential phosphorylation sites does not affect APIP activity whereas mutation of the potential zinc binding site completely abrogates it. Finally, we show that the N-terminal region of APIP that is missing in the short isoform is required for activity. Together, these results confirm the involvement of APIP in the methionine salvage pathway, which plays a key role in many biological functions like cancer, apoptosis, microbial proliferation and inflammation.
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Affiliation(s)
- Camille Mary
- CALIPHO Group, SIB-Swiss Institute of Bioinformatics, University of Geneva, Geneva, Switzerland.
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Polyamine metabolism in fungi with emphasis on phytopathogenic species. JOURNAL OF AMINO ACIDS 2012; 2012:837932. [PMID: 22957208 PMCID: PMC3432380 DOI: 10.1155/2012/837932] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 06/23/2012] [Indexed: 12/23/2022]
Abstract
Polyamines are essential metabolites present in all living organisms, and this subject has attracted the attention of researchers worldwide interested in defining their mode of action in the variable cell functions in which they are involved, from growth to development and differentiation. Although the mechanism of polyamine synthesis is almost universal, different biological groups show interesting differences in this aspect that require to be further analyzed. For these studies, fungi represent interesting models because of their characteristics and facility of analysis. During the last decades fungi have contributed to the understanding of polyamine metabolism. The use of specific inhibitors and the isolation of mutants have allowed the manipulation of the pathway providing information on its regulation. During host-fungus interaction polyamine metabolism suffers striking changes in response to infection, which requires examination. Additionally the role of polyamine transporter is getting importance because of its role in polyamine regulation. In this paper we analyze the metabolism of polyamines in fungi, and the difference of this process with other biological groups. Of particular importance is the difference of polyamine biosynthesis between fungi and plants, which makes this process an attractive target for the control of phytopathogenic fungi.
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Chattopadhyay MK, Fernandez C, Sharma D, McPhie P, Masison DC. Yeast ornithine decarboxylase and antizyme form a 1:1 complex in vitro: purification and characterization of the inhibitory complex. Biochem Biophys Res Commun 2011; 406:177-82. [PMID: 21295540 DOI: 10.1016/j.bbrc.2011.01.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 01/31/2011] [Indexed: 11/26/2022]
Abstract
Saccharomyces cerevisiae antizyme (AZ) resembles mammalian AZ in its mode of synthesis by translational frameshifting and its ability to inhibit and facilitate the degradation of ornithine decarboxylase (ODC). Despite many studies on the interaction of AZ and ODC, the ODC:AZ complex has not been purified from any source and thus clear information about the stoichiometry of the complex is still lacking. In this study we have studied the yeast antizyme protein and the ODC:AZ complex. The far UV CD spectrum of the full-length antizyme shows that the yeast protein consists of 51% β-sheet, 19% α-helix, and 24% coils. Surface plasmon resonance analyses show that the association constant (K(A)) between yeast AZ and yeast ODC is 6×10(7) (M(-1)). Using purified His-tagged AZ as a binding partner, we have purified the ODC:AZ inhibitory complex. The isolated complex has no ODC activity. The molecular weight of the complex is 90 kDa, which indicates a one to one stoichiometric binding of AZ and ODC in vitro. Comparison of the circular dichroism (CD) spectra of the two individual proteins and of the ODC:AZ complex shows a change in the secondary structure in the complex.
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Affiliation(s)
- Manas K Chattopadhyay
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, Bldg. 8, Bethesda, MD 20892, USA.
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Kakehi JI, Kuwashiro Y, Motose H, Igarashi K, Takahashi T. Norspermine substitutes for thermospermine in the control of stem elongation in Arabidopsis thaliana. FEBS Lett 2010; 584:3042-6. [DOI: 10.1016/j.febslet.2010.05.035] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/16/2010] [Accepted: 05/17/2010] [Indexed: 11/30/2022]
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Albers E. Metabolic characteristics and importance of the universal methionine salvage pathway recycling methionine from 5â²-methylthioadenosine. IUBMB Life 2009; 61:1132-42. [DOI: 10.1002/iub.278] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Chattopadhyay MK, Park MH, Tabor H. Hypusine modification for growth is the major function of spermidine in Saccharomyces cerevisiae polyamine auxotrophs grown in limiting spermidine. Proc Natl Acad Sci U S A 2008; 105:6554-9. [PMID: 18451031 PMCID: PMC2373341 DOI: 10.1073/pnas.0710970105] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Indexed: 11/18/2022] Open
Abstract
Spermidine and its derivative, hypusinated eIF5A, are essential for the growth of Saccharomyces cerevisiae. Very low concentrations of spermidine (10(-8) M) are sufficient for the growth of S. cerevisiae polyamine auxotrophs (spe1Delta, spe2Delta, and spe3Delta). Under these conditions, even though the growth rate is near normal, the internal concentration of spermidine is <0.2% of the spermidine concentration present in wild-type cells. When spe2Delta cells are grown with low concentrations of spermidine, there is a large decrease in the amount of hypusinated eukaryotic initiation factor 5A (eIF5A) (1/20 of normal), even though there is no change in the amount of total (modified plus unmodified) eIF5A. It is striking that, as intracellular spermidine becomes limiting, an increasing portion of it (up to 54%) is used for the hypusine modification of eIF5A. These data indicate that hypusine modification of eIF5A is a most important function for spermidine in supporting the growth of S. cerevisiae polyamine auxotrophs.
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Affiliation(s)
- Manas K. Chattopadhyay
- *Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases
| | - Myung Hee Park
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892
| | - Herbert Tabor
- *Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases
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Oram SW, Ai J, Pagani GM, Hitchens MR, Stern JA, Eggener S, Pins M, Xiao W, Cai X, Haleem R, Jiang F, Pochapsky TC, Hedstrom L, Wang Z. Expression and function of the human androgen-responsive gene ADI1 in prostate cancer. Neoplasia 2007; 9:643-51. [PMID: 17786183 PMCID: PMC1950434 DOI: 10.1593/neo.07415] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 06/22/2007] [Accepted: 06/23/2007] [Indexed: 12/25/2022] Open
Abstract
We have previously identified an androgen-responsive gene in rat prostate that shares homology with the aci-reductone dioxygenase (ARD/ARD') family of metal-binding enzymes involved in methionine salvage. We found that the gene, aci-reductone dioxygenase 1 (ADI1), was downregulated in prostate cancer cells, whereas enforced expression of rat Adi1 in these cells caused apoptosis. Here we report the characterization of human ADI1 in prostate cancer. Androgens induced ADI1 expression in human prostate cancer LNCaP cells, which was not blocked by cycloheximide, indicating that ADI1 is a primary androgen-responsive gene. In human benign prostatic hyperplasia specimens, epithelial cells expressed ADI1. Immunohistochemistry of prostate tumor tissue microarrays showed that benign regions expressed more ADI1 than tumors, suggesting a suppressive role for ADI1 in prostate cancer. Bacterial lysates containing recombinant ADI1 produced a five-fold increase in aci-reductone decay over controls, demonstrating that ADI1 has ARD activity. We generated point mutations at key residues in the metal-binding site of ADI1 to disrupt ARD function, and we found that these mutations did not affect intracellular localization, apoptosis, or colony formation suppression in human prostate cancer cells. Collectively, these observations argue that ADI1 may check prostate cancer progression through apoptosis and that this activity does not require metal binding.
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Affiliation(s)
- Shane W Oram
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Junkui Ai
- Department of Urology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA
| | - Gina M Pagani
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
| | - Moira R Hitchens
- Department of Urology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA
| | - Jeffrey A Stern
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Scott Eggener
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Michael Pins
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Wuhan Xiao
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Xiaoyan Cai
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Riffat Haleem
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Feng Jiang
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Thomas C Pochapsky
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
- Department of Chemistry, Brandeis University, Waltham, MA 02454, USA
| | - Lizbeth Hedstrom
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
- Department of Chemistry, Brandeis University, Waltham, MA 02454, USA
| | - Zhou Wang
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Department of Urology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, University of Pittsburgh Medical Center, Pittsburgh, PA 15232, USA
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Current awareness on yeast. Yeast 2006. [DOI: 10.1002/yea.1315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Chattopadhyay MK, Tabor CW, Tabor H. Methylthioadenosine and polyamine biosynthesis in a Saccharomyces cerevisiae meu1Δ mutant. Biochem Biophys Res Commun 2006; 343:203-7. [PMID: 16530730 DOI: 10.1016/j.bbrc.2006.02.144] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 02/24/2006] [Indexed: 11/29/2022]
Abstract
As part of our studies on polyamine biosynthesis in yeast, the metabolism of methylthioadenosine was studied in a mutant that lacks methylthioadenosine phosphorylase (meu1delta). The nucleoside accumulates in this mutant and is mainly excreted into the culture medium. Intracellular accumulation of the nucleoside is enough to account for the inhibition of spermidine synthase and thus to indirectly regulate the polyamine content of the meu1delta cells. By comparing the results with this mutant with a meu1delta spe2delta mutant that cannot synthesize spermidine or spermine, we showed that >98% of methylthioadenosine is produced as a byproduct of polyamine synthesis (i.e., from decarboxylated S-adenosylmethionine). In contrast, in MEU1+ SPE2+ cells methylthioadenosine does not accumulate and is metabolized through the methionine salvage pathway. Using a met15delta mutant we show that this pathway (i.e., involving polyamine biosynthesis and methylthioadenosine metabolism) is a significant factor in the metabolism of methionine, accounting for 15% of the added methionine.
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Affiliation(s)
- Manas K Chattopadhyay
- Laboratory of Biochemistry and Genetics, Building 8, Room 223, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Ornithine decarboxylase (ODC) initiates the polyamine biosynthetic pathway. The amount of ODC is altered in response to many growth factors, oncogenes, and tumor promoters and to changes in polyamine levels. Susceptibility to tumor development is increased in transgenic mice expressing high levels of ODC and is decreased in mice with reduced ODC due to loss of one ODC allele or elevated expression of antizyme, a protein that stimulates ODC degradation. This review describes key factors that contribute to the regulation of ODC levels, which can occur at the levels of transcription, translation, and protein turnover.
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Affiliation(s)
- Anthony E Pegg
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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