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Prasad Y, Kumar R, Chaudhary AK, Dhanaraju R, Majumdar S, Rao DN. Kinetic and catalytic properties of M.HpyAXVII, a phase-variable DNA methyltransferase from Helicobacter pylori. J Biol Chem 2018; 294:1019-1034. [PMID: 30478171 DOI: 10.1074/jbc.ra118.003769] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 11/10/2018] [Indexed: 01/26/2023] Open
Abstract
The bacterium Helicobacter pylori is one of the most common infectious agents found in the human stomach. H. pylori has an unusually large number of DNA methyltransferases (MTases), prompting speculation that they may be involved in the cancerization of epithelial cells. The mod-4a/4b locus, consisting of the hp1369 and hp1370 ORFs, encodes for a truncated and inactive MTase in H. pylori strain 26695. However, slipped-strand synthesis within the phase-variable polyguanine tract in hp1369 results in expression of an active HP1369-1370 fusion N 6-adenine methyltransferase, designated M.HpyAXVII. Sequence analysis of the mod-4a/4b locus across 74 H. pylori strain genomes has provided insights into the regulation of M.HpyAXVII expression. To better understand the role of M.HpyAXVII in the H. pylori biology, here we cloned and overexpressed the hp1369-70 fusion construct in Escherichia coli BL21(DE3) cells. Results from size-exclusion chromatography and multi-angle light scattering (MALS) analyses suggested that M.HpyAXVII exists as a dimer in solution. Kinetic studies, including product and substrate inhibition analyses, initial velocity dependence between substrates, and isotope partitioning, suggested that M.HpyAXVII catalyzes DNA methylation in an ordered Bi Bi mechanism in which the AdoMet binding precedes DNA binding and AdoMet's methyl group is then transferred to an adenine within the DNA recognition sequence. Altering the highly conserved catalytic motif (DPP(Y/F)) as well as the AdoMet-binding motif (FXGXG) by site-directed mutagenesis abolished the catalytic activity of M.HpyAXVII. These results provide insights into the enzyme kinetic mechanism of M.HpyAXVII. We propose that AdoMet binding conformationally "primes" the enzyme for DNA binding.
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Affiliation(s)
- Yedu Prasad
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, Karnataka, India and
| | - Ritesh Kumar
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, Karnataka, India and
| | - Awanish Kumar Chaudhary
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, Karnataka, India and
| | - Rajkumar Dhanaraju
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, Karnataka, India and
| | - Soneya Majumdar
- Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur-208016, Uttar Pradesh, India
| | - Desirazu N Rao
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, Karnataka, India and
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Ma B, Ma J, Liu D, Guo L, Chen H, Ding J, Liu W, Zhang H. Biochemical and structural characterization of a DNA N6-adenine methyltransferase from Helicobacter pylori. Oncotarget 2018; 7:40965-40977. [PMID: 27259995 PMCID: PMC5173035 DOI: 10.18632/oncotarget.9692] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 05/17/2016] [Indexed: 11/25/2022] Open
Abstract
DNA N6-methyladenine modification plays an important role in regulating a variety of biological functions in bacteria. However, the mechanism of sequence-specific recognition in N6-methyladenine modification remains elusive. M1.HpyAVI, a DNA N6-adenine methyltransferase from Helicobacter pylori, shows more promiscuous substrate specificity than other enzymes. Here, we present the crystal structures of cofactor-free and AdoMet-bound structures of this enzyme, which were determined at resolutions of 3.0 Å and 3.1 Å, respectively. The core structure of M1.HpyAVI resembles the canonical AdoMet-dependent MTase fold, while the putative DNA binding regions considerably differ from those of the other MTases, which may account for the substrate promiscuity of this enzyme. Site-directed mutagenesis experiments identified residues D29 and E216 as crucial amino acids for cofactor binding and the methyl transfer activity of the enzyme, while P41, located in a highly flexible loop, playing a determinant role for substrate specificity. Taken together, our data revealed the structural basis underlying DNA N6-adenine methyltransferase substrate promiscuity.
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Affiliation(s)
- Bo Ma
- Department of Human Anatomy, Histology and Embryology, Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, Beijing, China
| | - Ji Ma
- Department of Human Anatomy, Histology and Embryology, Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, Beijing, China
| | - Dong Liu
- Institute of Immunology, The Third Military Medical University, Chongqing, China
| | - Ling Guo
- Institute of Immunology, The Third Military Medical University, Chongqing, China
| | - Huiling Chen
- Institute of Immunology, The Third Military Medical University, Chongqing, China
| | - Jingjin Ding
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wei Liu
- Institute of Immunology, The Third Military Medical University, Chongqing, China
| | - Hongquan Zhang
- Department of Human Anatomy, Histology and Embryology, Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, Beijing, China
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DNA adenine hypomethylation leads to metabolic rewiring in Deinococcus radiodurans. J Proteomics 2015; 126:131-9. [DOI: 10.1016/j.jprot.2015.05.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/22/2015] [Accepted: 05/30/2015] [Indexed: 12/27/2022]
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Dwivedi GR, Srikanth KD, Anand P, Naikoo J, Srilatha NS, Rao DN. Insights into the Functional Roles of N-Terminal and C-Terminal Domains of Helicobacter pylori DprA. PLoS One 2015; 10:e0131116. [PMID: 26135134 PMCID: PMC4489622 DOI: 10.1371/journal.pone.0131116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 05/28/2015] [Indexed: 12/04/2022] Open
Abstract
DNA processing protein A (DprA) plays a crucial role in the process of natural transformation. This is accomplished through binding and subsequent protection of incoming foreign DNA during the process of internalization. DprA along with Single stranded DNA binding protein A (SsbA) acts as an accessory factor for RecA mediated DNA strand exchange. H. pylori DprA (HpDprA) is divided into an N-terminal domain and a C- terminal domain. In the present study, individual domains of HpDprA have been characterized for their ability to bind single stranded (ssDNA) and double stranded DNA (dsDNA). Oligomeric studies revealed that HpDprA possesses two sites for dimerization which enables HpDprA to form large and tightly packed complexes with ss and dsDNA. While the N-terminal domain was found to be sufficient for binding with ss or ds DNA, C-terminal domain has an important role in the assembly of poly-nucleoprotein complex. Using site directed mutagenesis approach, we show that a pocket comprising positively charged amino acids in the N-terminal domain has an important role in the binding of ss and dsDNA. Together, a functional cross talk between the two domains of HpDprA facilitating the binding and formation of higher order complex with DNA is discussed.
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Affiliation(s)
| | | | - Praveen Anand
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Javed Naikoo
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - N. S. Srilatha
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Desirazu N. Rao
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
- * E-mail:
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Furuta Y, Namba-Fukuyo H, Shibata TF, Nishiyama T, Shigenobu S, Suzuki Y, Sugano S, Hasebe M, Kobayashi I. Methylome diversification through changes in DNA methyltransferase sequence specificity. PLoS Genet 2014; 10:e1004272. [PMID: 24722038 PMCID: PMC3983042 DOI: 10.1371/journal.pgen.1004272] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 02/13/2014] [Indexed: 12/20/2022] Open
Abstract
Epigenetic modifications such as DNA methylation have large effects on gene expression and genome maintenance. Helicobacter pylori, a human gastric pathogen, has a large number of DNA methyltransferase genes, with different strains having unique repertoires. Previous genome comparisons suggested that these methyltransferases often change DNA sequence specificity through domain movement--the movement between and within genes of coding sequences of target recognition domains. Using single-molecule real-time sequencing technology, which detects N6-methyladenines and N4-methylcytosines with single-base resolution, we studied methylated DNA sites throughout the H. pylori genome for several closely related strains. Overall, the methylome was highly variable among closely related strains. Hypermethylated regions were found, for example, in rpoB gene for RNA polymerase. We identified DNA sequence motifs for methylation and then assigned each of them to a specific homology group of the target recognition domains in the specificity-determining genes for Type I and other restriction-modification systems. These results supported proposed mechanisms for sequence-specificity changes in DNA methyltransferases. Knocking out one of the Type I specificity genes led to transcriptome changes, which suggested its role in gene expression. These results are consistent with the concept of evolution driven by DNA methylation, in which changes in the methylome lead to changes in the transcriptome and potentially to changes in phenotype, providing targets for natural or artificial selection.
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Affiliation(s)
- Yoshikazu Furuta
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Minato-ku, Tokyo, Japan
- Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Hiroe Namba-Fukuyo
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Minato-ku, Tokyo, Japan
| | | | - Tomoaki Nishiyama
- Advanced Science Research Center, Kanazawa University, Kanazawa, Japan
| | - Shuji Shigenobu
- National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki, Japan
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Sumio Sugano
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki, Japan
| | - Ichizo Kobayashi
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Minato-ku, Tokyo, Japan
- Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
- * E-mail:
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Vasu K, Nagaraja V. Diverse functions of restriction-modification systems in addition to cellular defense. Microbiol Mol Biol Rev 2013; 77:53-72. [PMID: 23471617 PMCID: PMC3591985 DOI: 10.1128/mmbr.00044-12] [Citation(s) in RCA: 376] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Restriction-modification (R-M) systems are ubiquitous and are often considered primitive immune systems in bacteria. Their diversity and prevalence across the prokaryotic kingdom are an indication of their success as a defense mechanism against invading genomes. However, their cellular defense function does not adequately explain the basis for their immaculate specificity in sequence recognition and nonuniform distribution, ranging from none to too many, in diverse species. The present review deals with new developments which provide insights into the roles of these enzymes in other aspects of cellular function. In this review, emphasis is placed on novel hypotheses and various findings that have not yet been dealt with in a critical review. Emerging studies indicate their role in various cellular processes other than host defense, virulence, and even controlling the rate of evolution of the organism. We also discuss how R-M systems could have successfully evolved and be involved in additional cellular portfolios, thereby increasing the relative fitness of their hosts in the population.
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Affiliation(s)
- Kommireddy Vasu
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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Dwivedi GR, Sharma E, Rao DN. Helicobacter pylori DprA alleviates restriction barrier for incoming DNA. Nucleic Acids Res 2013; 41:3274-88. [PMID: 23355610 PMCID: PMC3597690 DOI: 10.1093/nar/gkt024] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Helicobacter pylori is a Gram-negative bacterium that colonizes human stomach and causes gastric inflammation. The species is naturally competent and displays remarkable diversity. The presence of a large number of restriction-modification (R-M) systems in this bacterium creates a barrier against natural transformation by foreign DNA. Yet, mechanisms that protect incoming double-stranded DNA (dsDNA) from restriction enzymes are not well understood. A DNA-binding protein, DNA Processing Protein A (DprA) has been shown to facilitate natural transformation of several Gram-positive and Gram-negative bacteria by protecting incoming single-stranded DNA (ssDNA) and promoting RecA loading on it. However, in this study, we report that H. pylori DprA (HpDprA) binds not only ssDNA but also dsDNA thereby conferring protection to both from various exonucleases and Type II restriction enzymes. Here, we observed a stimulatory role of HpDprA in DNA methylation through physical interaction with methyltransferases. Thus, HpDprA displayed dual functional interaction with H. pylori R-M systems by not only inhibiting the restriction enzymes but also stimulating methyltransferases. These results indicate that HpDprA could be one of the factors that modulate the R-M barrier during inter-strain natural transformation in H. pylori.
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Abstract
In prokaryotes, alteration in gene expression was observed with the modification of DNA, especially DNA methylation. Such changes are inherited from generation to generation with no alterations in the DNA sequence and represent the epigenetic signal in prokaryotes. DNA methyltransferases are enzymes involved in DNA modification and thus in epigenetic regulation of gene expression. DNA methylation not only affects the thermodynamic stability of DNA, but also changes its curvature. Methylation of specific residues on DNA can affect the protein-DNA interactions. DNA methylation in prokaryotes regulates a number of physiological processes in the bacterial cell including transcription, DNA mismatch repair and replication initiation. Significantly, many reports have suggested a role of DNA methylation in regulating the expression of a number of genes in virulence and pathogenesis thus, making DNA methlytransferases novel targets for the designing of therapeutics. Here, we summarize the current knowledge about the influence of DNA methylation on gene regulation in different bacteria, and on bacterial virulence.
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Affiliation(s)
- Ritesh Kumar
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India,
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Kumar R, Mukhopadhyay AK, Ghosh P, Rao DN. Comparative transcriptomics of H. pylori strains AM5, SS1 and their hpyAVIBM deletion mutants: possible roles of cytosine methylation. PLoS One 2012; 7:e42303. [PMID: 22879937 PMCID: PMC3411764 DOI: 10.1371/journal.pone.0042303] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 07/05/2012] [Indexed: 12/13/2022] Open
Abstract
Helicobacter pylori is an important human pathogen and one of the most successful chronic colonizers of the human body. H. pylori uses diverse mechanisms to modulate its interaction with the host in order to promote chronic infection and overcome host immune response. Restriction-modification genes are a major part of strain-specific genes present in H. pylori. The role of N6 - adenine methylation in bacterial gene regulation and virulence is well established but not much is known about the effect of C5 -cytosine methylation on gene expression in prokaryotes. In this study, it was observed by microarray analysis and RT-PCR, that deletion of an orphan C5 -cytosine methyltransferase, hpyAVIBM in H. pylori strains AM5and SS1 has a significant effect on the expression of number of genes belonging to motility, adhesion and virulence. AM5ΔhpyAVIBM mutant strain has a different LPS profile and is able to induce high IL-8 production compared to wild-type. hpyAVIBM from strain 26695 is able to complement mutant SS1 and AM5 strains. This study highlights a possible significance of cytosine methylation in the physiology of H. pylori.
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Affiliation(s)
- Ritesh Kumar
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Asish K. Mukhopadhyay
- Division of Bacteriology, National Institute of Cholera and Enteric Disease, Kolkata, India
| | - Prachetash Ghosh
- Division of Bacteriology, National Institute of Cholera and Enteric Disease, Kolkata, India
| | - Desirazu N. Rao
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
- * E-mail:
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Kumar R, Sabareesh V, Mukhopadhyay AK, Rao DN. Mutations in hpyAVIBM, C⁵ cytosine DNA methyltransferase from Helicobacter pylori result in relaxed specificity. FEBS J 2012; 279:1080-92. [PMID: 22269034 DOI: 10.1111/j.1742-4658.2012.08502.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The genome of Helicobacter pylori is rich in restriction-modification (RM) systems. Approximately 4% of the genome codes for components of RM systems. hpyAVIBM, which codes for a phase-variable C(5) cytosine methyltransferase (MTase) from H. pylori, lacks a cognate restriction enzyme. Over-expression of M.HpyAVIB in Escherichia coli enhances the rate of mutations. However, when the catalytically inactive F9N or C82W mutants of M.HpyAVIB were expressed in E. coli, mutations were not observed. The M.HpyAVIB gene itself was mutated to give rise to different variants of the MTase. M.HpyAVIB variants were purified and differences in kinetic properties and specificity were observed. Intriguingly, purified MTase variants showed relaxed substrate specificity. Homologues of hpyAVIBM homologues amplified and sequenced from different clinical isolates showed similar variations in sequence. Thus, hpyAVIBM presents an interesting example of allelic variations in H. pylori where changes in the nucleotide sequence result in proteins with new properties.
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Affiliation(s)
- Ritesh Kumar
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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A nucleotide insertion between two adjacent methyltransferases in Helicobacter pylori results in a bifunctional DNA methyltransferase. Biochem J 2011; 433:487-95. [PMID: 21110832 DOI: 10.1042/bj20101668] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Helicobacter pylori has a dynamic R-M (restriction-modification) system. It is capable of acquiring new R-M systems from the environment in the form of DNA released from other bacteria or other H. pylori strains. Random mutations in R-M genes can result in non-functional R-M systems or R-M systems with new properties. hpyAVIAM and hpyAVIBM are two solitary DNA MTase (methyltransferase) genes adjacent to each other and lacking a cognate restriction enzyme gene in H. pylori strain 26695. Interestingly, in an Indian strain D27, hpyAVIAM-hpyAVIBM encodes a single bifunctional polypeptide due to insertion of a nucleotide just before the stop codon of hpyAVIBM and, when a similar mutation was made in hpyAVIAM-hpyAVIBM from strain 26695, a functional MTase with an N-terminal C⁵-cytosine MTase domain and a C-terminal N⁶-adenine MTase domain was constructed. Mutations in the AdoMet (S-adenosylmethionine)-binding motif or in the catalytic motif of M.HpyAVIA or M.HpyAVIB selectively abrogated the C⁵-cytosine or N⁶-adenine methylation activity of M.HpyAVIA-M.HpyAVIB fusion protein. The present study highlights the ability of H. pylori to evolve genes with unique functions and thus generate variability. For organisms such as H. pylori, which have a small genome, these adaptations could be important for their survival in the hostile host environment.
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Corrigendum. FEBS J 2010. [DOI: 10.1111/j.1742-4658.2010.07713.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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