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McKitterick AC, Hays SG, Johura FT, Alam M, Seed KD. Viral Satellites Exploit Phage Proteins to Escape Degradation of the Bacterial Host Chromosome. Cell Host Microbe 2019; 26:504-514.e4. [PMID: 31600502 PMCID: PMC6910227 DOI: 10.1016/j.chom.2019.09.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/06/2019] [Accepted: 09/12/2019] [Indexed: 01/10/2023]
Abstract
Phage defense systems are often found on mobile genetic elements (MGEs), where they constitutively defend against invaders or are induced to respond to new assaults. Phage satellites, one type of MGE, are induced during phage infection to promote their own transmission, reducing phage production and protecting their hosts in the process. One such satellite in Vibrio cholerae, phage-inducible chromosomal island-like element (PLE), sabotages the lytic phage ICP1, which triggers PLE excision from the bacterial chromosome, replication, and transduction to neighboring cells. Analysis of patient stool samples from different geographic regions revealed that ICP1 has evolved to possess one of two syntenic loci encoding an SF1B-type helicase, either of which PLE exploits to drive replication. Further, loss of PLE mobilization limits anti-phage activity because of phage-mediated degradation of the bacterial genome. Our work provides insight into the unique challenges facing parasites of lytic phages and underscores the adaptions of satellites to their ever-evolving target phage.
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Affiliation(s)
- Amelia C McKitterick
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA
| | - Stephanie G Hays
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA
| | - Fatema-Tuz Johura
- ICDDR,B, formerly known as International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Munirul Alam
- ICDDR,B, formerly known as International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Kimberley D Seed
- Department of Plant and Microbial Biology, University of California, Berkeley, 271 Koshland Hall, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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Suter MA, Chen A, Burdine MS, Choudhury M, Harris RA, Lane RH, Friedman JE, Grove KL, Tackett AJ, Aagaard KM. A maternal high-fat diet modulates fetal SIRT1 histone and protein deacetylase activity in nonhuman primates. FASEB J 2012; 26:5106-14. [PMID: 22982377 DOI: 10.1096/fj.12-212878] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In nonhuman primates, we previously demonstrated that a maternal high-fat diet (MHFD) induces fetal nonalcoholic fatty liver disease (NAFLD) and alters the fetal metabolome. These changes are accompanied by altered acetylation of histone H3 (H3K14ac). However, the mechanism behind this alteration in acetylation remains unknown. As SIRT1 is both a lysine deacetylase and a crucial sensor of cellular metabolism, we hypothesized that SIRT1 may be involved in fetal epigenomic alterations. Here we show that in utero exposure to a MHFD, but not maternal obesity per se, increases fetal H3K14ac with concomitant decreased SIRT1 expression and diminished in vitro protein and histone deacetylase activity. MHFD increased H3K14ac and DBC1-SIRT1 complex formation in fetal livers, both of which were abrogated with diet reversal despite persistent maternal obesity. Moreover, MHFD was associated with altered expression of known downstream effectors deregulated in NAFLD and modulated by SIRT1 (e.g., PPARΑ, PPARG, SREBF1, CYP7A1, FASN, and SCD). Finally, ex vivo purified SIRT1 retains deacetylase activity on an H3K14ac peptide substrate with preferential activity toward acetylated histone H3; mutagenesis of the catalytic domain of SIRT1 (H363Y) abrogates H3K14ac deacetylation. Our data implicate SIRT1 as a likely molecular mediator of the fetal epigenome and metabolome under MHFD conditions.
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Affiliation(s)
- Melissa A Suter
- Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Baylor College of Medicine, Houston, TX 77030, USA
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He X, Byrd AK, Yun MK, Pemble CW, Harrison D, Yeruva L, Dahl C, Kreuzer KN, Raney KD, White SW. The T4 phage SF1B helicase Dda is structurally optimized to perform DNA strand separation. Structure 2012; 20:1189-200. [PMID: 22658750 DOI: 10.1016/j.str.2012.04.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/19/2012] [Accepted: 04/21/2012] [Indexed: 10/28/2022]
Abstract
Helicases move on DNA via an ATP binding and hydrolysis mechanism coordinated by well-characterized helicase motifs. However, the translocation along single-stranded DNA (ssDNA) and the strand separation of double-stranded (dsDNA) may be loosely or tightly coupled. Dda is a phage T4 SF1B helicase with sequence homology to the Pif1 family of helicases that tightly couples translocation to strand separation. The crystal structure of the Dda-ssDNA binary complex reveals a domain referred to as the "pin" that was previously thought to remain static during strand separation. The pin contains a conserved phenylalanine that mediates a transient base-stacking interaction that is absolutely required for separation of dsDNA. The pin is secured at its tip by protein-protein interactions through an extended SH3 domain thereby creating a rigid strut. The conserved interface between the pin and the SH3 domain provides the mechanism for tight coupling of translocation to strand separation.
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Affiliation(s)
- Xiaoping He
- Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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Ran T, Lu T, Yuan H, Liu H, Wang J, Zhang W, Leng Y, Lin G, Zhuang S, Chen Y. A selectivity study on mTOR/PI3Kα inhibitors by homology modeling and 3D-QSAR. J Mol Model 2011; 18:171-86. [PMID: 21523553 DOI: 10.1007/s00894-011-1034-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 03/09/2011] [Indexed: 11/30/2022]
Abstract
The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway plays a critical role in the regulation of cellular growth, survival and proliferation. mTOR and PI3K have attracted particular attention as cancer targets. These kinases belong to the phosphatidylinositol-3-kinase-related kinase (PIKK) family and therefore have considerable homology in their active sites. To accelerate the discovery of inhibitors with selective activity against mTOR and PI3K as cancer targets, in this work, a homology model of mTOR was developed to identify the structural divergence in the active sites between mTOR and PI3Kα. Furthermore, two highly predictive comparative molecular similarity index analyses (CoMSIA) models were built based on 304 selective inhibitors docked into mTOR and PI3Kα, respectively (mTOR: q(2) = 0.658, r(pre)(2) = 0.839; PI3Kα: q(2) = 0.540, r(pre)(2) = 0.719). The results showed that steric and electrostatic fields have an important influence on selectivity towards mTOR and PI3Kα-a finding consistent with the structural divergence between the active sites. The findings may be helpful in investigating selective mTOR/PI3Kα inhibitors.
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Affiliation(s)
- Ting Ran
- Laboratory of Molecular Design and Drug Discovery, College of Basic Science, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing, China
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Hnízda A, Spiwok V, Jurga V, Kožich V, Kodíček M, Kraus JP. Cross-talk between the catalytic core and the regulatory domain in cystathionine β-synthase: study by differential covalent labeling and computational modeling. Biochemistry 2010; 49:10526-34. [PMID: 21062078 PMCID: PMC3146298 DOI: 10.1021/bi101384m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 11/09/2010] [Indexed: 12/22/2022]
Abstract
Cystathionine β-synthase (CBS) is a modular enzyme which catalyzes condensation of serine with homocysteine. Cross-talk between the catalytic core and the C-terminal regulatory domain modulates the enzyme activity. The regulatory domain imposes an autoinhibition action that is alleviated by S-adenosyl-l-methionine (AdoMet) binding, by deletion of the C-terminal regulatory module, or by thermal activation. The atomic mechanisms of the CBS allostery have not yet been sufficiently explained. Using pulse proteolysis in urea gradient and proteolytic kinetics with thermolysin under native conditions, we demonstrated that autoinhibition is associated with changes in conformational stability and with sterical hindrance of the catalytic core. To determine the contact area between the catalytic core and the autoinhibitory module of the CBS protein, we compared side-chain reactivity of the truncated CBS lacking the regulatory domain (45CBS) and of the full-length enzyme (wtCBS) using covalent labeling by six different modification agents and subsequent mass spectrometry. Fifty modification sites were identified in 45CBS, and four of them were not labeled in wtCBS. One differentially reactive site (cluster W408/W409/W410) is a part of the linker between the domains. The other three residues (K172 and/or K177, R336, and K384) are located in the same region of the 45CBS crystal structure; computational modeling showed that these amino acid side chains potentially form a regulatory interface in CBS protein. Subtle differences at CBS surface indicate that enzyme activity is not regulated by conformational conversions but more likely by different allosteric mechanisms.
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Affiliation(s)
- Aleš Hnízda
- Institute of Inherited Metabolic Disorders, First Medical Faculty, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, Prague 2, 128 00 Czech Republic
| | - Vojtěch Spiwok
- Department of Biochemistry and Microbiology, Institute of Chemical Technology in Prague, Technická 5, Prague 6, 166 28 Czech Republic
| | - Vojtěch Jurga
- Department of Biochemistry and Microbiology, Institute of Chemical Technology in Prague, Technická 5, Prague 6, 166 28 Czech Republic
| | - Viktor Kožich
- Institute of Inherited Metabolic Disorders, First Medical Faculty, Charles University in Prague and General University Hospital in Prague, Ke Karlovu 2, Prague 2, 128 00 Czech Republic
| | - Milan Kodíček
- Department of Biochemistry and Microbiology, Institute of Chemical Technology in Prague, Technická 5, Prague 6, 166 28 Czech Republic
| | - Jan P. Kraus
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
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Makowska-Grzyska MM, Ziebarth TD, Kaguni LS. Physical analysis of recombinant forms of the human mitochondrial DNA helicase. Methods 2010; 51:411-5. [PMID: 20347039 DOI: 10.1016/j.ymeth.2010.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2010] [Revised: 03/15/2010] [Accepted: 03/22/2010] [Indexed: 10/19/2022] Open
Abstract
Maintenance of the mitochondrial DNA (mtDNA) genome is dependent on numerous nuclear-encoded proteins including the mtDNA helicase, which is an essential component of the replicative machinery. Human mtDNA helicase shares a high degree of sequence similarity with the bacteriophage T7 primase-helicase gene 4 protein, and catalyzes duplex unwinding in the 5'-3' direction. As purified at 300 mM NaCl, the enzyme exists as a hexamer, with a modular architecture comprising distinct N- and C-terminal domains. We present here several methods that allow the identification of the oligomeric state of the human mtDNA helicase, and probe the modular architecture of the enzyme. Despite their relatively common usage, we believe that their versatility makes these techniques particularly helpful in the characterization of oligomeric proteins.
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Affiliation(s)
- Magdalena M Makowska-Grzyska
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
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