1
|
Milito A, Aschern M, McQuillan JL, Yang JS. Challenges and advances towards the rational design of microalgal synthetic promoters in Chlamydomonas reinhardtii. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:3833-3850. [PMID: 37025006 DOI: 10.1093/jxb/erad100] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 03/24/2023] [Indexed: 06/19/2023]
Abstract
Microalgae hold enormous potential to provide a safe and sustainable source of high-value compounds, acting as carbon-fixing biofactories that could help to mitigate rapidly progressing climate change. Bioengineering microalgal strains will be key to optimizing and modifying their metabolic outputs, and to render them competitive with established industrial biotechnology hosts, such as bacteria or yeast. To achieve this, precise and tuneable control over transgene expression will be essential, which would require the development and rational design of synthetic promoters as a key strategy. Among green microalgae, Chlamydomonas reinhardtii represents the reference species for bioengineering and synthetic biology; however, the repertoire of functional synthetic promoters for this species, and for microalgae generally, is limited in comparison to other commercial chassis, emphasizing the need to expand the current microalgal gene expression toolbox. Here, we discuss state-of-the-art promoter analyses, and highlight areas of research required to advance synthetic promoter development in C. reinhardtii. In particular, we exemplify high-throughput studies performed in other model systems that could be applicable to microalgae, and propose novel approaches to interrogating algal promoters. We lastly outline the major limitations hindering microalgal promoter development, while providing novel suggestions and perspectives for how to overcome them.
Collapse
Affiliation(s)
- Alfonsina Milito
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
| | - Moritz Aschern
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
| | - Josie L McQuillan
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
| | - Jae-Seong Yang
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain
| |
Collapse
|
2
|
Lenzini L, Di Patti F, Livi R, Fondi M, Fani R, Mengoni A. A Method for the Structure-Based, Genome-Wide Analysis of Bacterial Intergenic Sequences Identifies Shared Compositional and Functional Features. Genes (Basel) 2019; 10:genes10100834. [PMID: 31652625 PMCID: PMC6826451 DOI: 10.3390/genes10100834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/07/2019] [Accepted: 10/16/2019] [Indexed: 11/16/2022] Open
Abstract
In this paper, we propose a computational strategy for performing genome-wide analyses of intergenic sequences in bacterial genomes. Following similar directions of a previous paper, where a method for genome-wide analysis of eucaryotic Intergenic sequences was proposed, here we developed a tool for implementing similar concepts in bacteria genomes. This allows us to (i) classify intergenic sequences into clusters, characterized by specific global structural features and (ii) draw possible relations with their functional features.
Collapse
Affiliation(s)
- Leonardo Lenzini
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino, 50019, Italy.
- Istituto Nazionale di Fisica Nucleare, Sesto Fiorentino, 50019, Italy.
| | - Francesca Di Patti
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino, 50019, Italy.
- Centro Interdipartimentale per lo Studio delle Dinamiche Complesse, Sesto Fiorentino, 50019, Italy.
| | - Roberto Livi
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino, 50019, Italy.
- Istituto Nazionale di Fisica Nucleare, Sesto Fiorentino, 50019, Italy.
- Centro Interdipartimentale per lo Studio delle Dinamiche Complesse, Sesto Fiorentino, 50019, Italy.
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sesto Fiorentino, 50019, Italy.
| | - Marco Fondi
- Dipartimento di Biologia, Università degli Studi di Firenze, Sesto Fiorentino, 50019, Italy.
| | - Renato Fani
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sesto Fiorentino, 50019, Italy.
- Dipartimento di Biologia, Università degli Studi di Firenze, Sesto Fiorentino, 50019, Italy.
| | - Alessio Mengoni
- Dipartimento di Biologia, Università degli Studi di Firenze, Sesto Fiorentino, 50019, Italy.
| |
Collapse
|
3
|
Cencini M, Pigolotti S. Energetic funnel facilitates facilitated diffusion. Nucleic Acids Res 2019; 46:558-567. [PMID: 29216364 PMCID: PMC5778461 DOI: 10.1093/nar/gkx1220] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/24/2017] [Indexed: 01/25/2023] Open
Abstract
Transcription factors (TFs) are able to associate to their binding sites on DNA faster than the physical limit posed by diffusion. Such high association rates can be achieved by alternating between three-dimensional diffusion and one-dimensional sliding along the DNA chain, a mechanism-dubbed facilitated diffusion. By studying a collection of TF binding sites of Escherichia coli from the RegulonDB database and of Bacillus subtilis from DBTBS, we reveal a funnel in the binding energy landscape around the target sequences. We show that such a funnel is linked to the presence of gradients of AT in the base composition of the DNA region around the binding sites. An extensive computational study of the stochastic sliding process along the energetic landscapes obtained from the database shows that the funnel can significantly enhance the probability of TFs to find their target sequences when sliding in their proximity. We demonstrate that this enhancement leads to a speed-up of the association process.
Collapse
Affiliation(s)
- Massimo Cencini
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via dei Taurini 19, 00185 Rome, Italy
| | - Simone Pigolotti
- Biological Complexity Unit, Okinawa Institute of Science and Technology and Graduate University, Onna, Okinawa 904-0495, Japan.,Max Planck Institute for the Physics of Complex Systems, Nöthnitzerstraße 38, 01187 Dresden, Germany.,Departament de Fisica, Universitat Politecnica de Catalunya Edif. GAIA, Rambla Sant Nebridi 22, 08222 Terrassa, Barcelona, Spain
| |
Collapse
|
4
|
Exploration of the Germline Genome of the Ciliate Chilodonella uncinata through Single-Cell Omics (Transcriptomics and Genomics). mBio 2018; 9:mBio.01836-17. [PMID: 29317511 PMCID: PMC5760741 DOI: 10.1128/mbio.01836-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Separate germline and somatic genomes are found in numerous lineages across the eukaryotic tree of life, often separated into distinct tissues (e.g., in plants, animals, and fungi) or distinct nuclei sharing a common cytoplasm (e.g., in ciliates and some foraminifera). In ciliates, germline-limited (i.e., micronuclear-specific) DNA is eliminated during the development of a new somatic (i.e., macronuclear) genome in a process that is tightly linked to large-scale genome rearrangements, such as deletions and reordering of protein-coding sequences. Most studies of germline genome architecture in ciliates have focused on the model ciliates Oxytricha trifallax, Paramecium tetraurelia, and Tetrahymena thermophila, for which the complete germline genome sequences are known. Outside of these model taxa, only a few dozen germline loci have been characterized from a limited number of cultivable species, which is likely due to difficulties in obtaining sufficient quantities of “purified” germline DNA in these taxa. Combining single-cell transcriptomics and genomics, we have overcome these limitations and provide the first insights into the structure of the germline genome of the ciliate Chilodonella uncinata, a member of the understudied class Phyllopharyngea. Our analyses reveal the following: (i) large gene families contain a disproportionate number of genes from scrambled germline loci; (ii) germline-soma boundaries in the germline genome are demarcated by substantial shifts in GC content; (iii) single-cell omics techniques provide large-scale quality germline genome data with limited effort, at least for ciliates with extensively fragmented somatic genomes. Our approach provides an efficient means to understand better the evolution of genome rearrangements between germline and soma in ciliates. Our understanding of the distinctions between germline and somatic genomes in ciliates has largely relied on studies of a few model genera (e.g., Oxytricha, Paramecium, Tetrahymena). We have used single-cell omics to explore germline-soma distinctions in the ciliate Chilodonella uncinata, which likely diverged from the better-studied ciliates ~700 million years ago. The analyses presented here indicate that developmentally regulated genome rearrangements between germline and soma are demarcated by rapid transitions in local GC composition and lead to diversification of protein families. The approaches used here provide the basis for future work aimed at discerning the evolutionary impacts of germline-soma distinctions among diverse ciliates.
Collapse
|
5
|
Deng C, Li J, Shin HD, Du G, Chen J, Liu L. Efficient expression of cyclodextrin glycosyltransferase from Geobacillus stearothermophilus in Escherichia coli by promoter engineering and downstream box evolution. J Biotechnol 2017; 266:77-83. [PMID: 29247671 DOI: 10.1016/j.jbiotec.2017.12.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 10/14/2017] [Accepted: 12/09/2017] [Indexed: 11/28/2022]
Abstract
Cyclodextrin glycosyltransferase (CGTase) catalyzes hydrolysis, cyclization, coupling, and disproportionation reactions and is widely used in the starch processing industry. In this work, the expression of CGTase from Geobacillus stearothermophilus in Escherichia coli BL21 (DE3) was significantly improved by promoter engineering and downstream box evolution. Firstly, the effects of the promoter type (PT7, Ptrp, PlacUV5, and the hybrid promoters PtacI and PtacII) and spacer sequence on the expression of CGTase were examined. PtacI demonstrated the highest rate of transcriptional activity, which was 4.4-, 7.1-, 3.3-, and 1.5-fold greater than that of PT7, Ptrp, PlacUV5, and PtacII, respectively. The spacer sequence of the promoter was optimized using a degenerate base library, and the GC content of the spacer was found to be inversely proportional to CGTase expression. In addition, CGTase expression was higher when TG:CA and TA:TA dimers were present in the spacer sequence. Under the control of the PtacI promoter with an optimized spacer sequence, extracellular CGTase activity reached 170.6 U/mL, which was seven times higher than that of the original strain (25.2 U/mL). Directed evolution of the downstream box sequence was then performed by randomization of the sequence using degenerate codons, similarly as for the optimization of the spacer sequence. After optimizing the downstream box sequence, CGTase activity increased from 170.6 to 214 U/mL. The results obtained here indicate that in addition to promoter type, the spacer sequence of the promoter and the downstream box are important target elements for improved gene expression.
Collapse
Affiliation(s)
- Chen Deng
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Hyun-Dong Shin
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, 30332, USA
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jian Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.
| |
Collapse
|
6
|
Li X, Doukhan P, Feugeas JP. Statistical inference for DNA sequences of promoters: a non-stationary qualitative model. STATISTICS-ABINGDON 2016. [DOI: 10.1080/02331888.2016.1261474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Xiaoyin Li
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH, USA
| | - Paul Doukhan
- AGM, Department of Mathematics, University of Cergy-Pontoise & IUF, Ile de France, Cergy-Pontoise, France
| | | |
Collapse
|
7
|
Scranton MA, Ostrand JT, Georgianna DR, Lofgren SM, Li D, Ellis RC, Carruthers DN, Dräger A, Masica DL, Mayfield SP. Synthetic promoters capable of driving robust nuclear gene expression in the green alga Chlamydomonas reinhardtii. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
8
|
Variation and constraints in species-specific promoter sequences. J Theor Biol 2014; 363:357-66. [PMID: 25149367 DOI: 10.1016/j.jtbi.2014.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/30/2014] [Accepted: 08/04/2014] [Indexed: 11/24/2022]
Abstract
A vast literature is nowadays devoted to the search of correlations between transcription related functions and the composition of sequences upstream the Transcription Start Site. Little is known about the possible functional effects of nucleotide distributions on the conformational landscape of DNA in such regions. We have used suitable statistical indicators for identifying sequences that may play an important role in regulating transcription processes. In particular, we have analyzed base composition, periodicity and information content in sets of aligned promoters clustered according to functional information in order to obtain an insight on the main structural differences between promoters regulating genes with different functions. Our results show that when we select promoters according to some biological information, in a single species, at least in vertebrates, we observe structurally different classes of sequences. The highly variable and differentiated gene expression patterns may explain the great extent of structural differentiation observed in complex organisms. In fact, despite our analysis is focused on Homo sapiens, we provide also a comparison with other species, selected at different positions in the phylogenetic tree.
Collapse
|
9
|
Genome-wide analysis of promoters: clustering by alignment and analysis of regular patterns. PLoS One 2014; 9:e85260. [PMID: 24465517 PMCID: PMC3898993 DOI: 10.1371/journal.pone.0085260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 11/26/2013] [Indexed: 01/08/2023] Open
Abstract
In this paper we perform a genome-wide analysis of H. sapiens promoters. To this aim, we developed and combined two mathematical methods that allow us to (i) classify promoters into groups characterized by specific global structural features, and (ii) recover, in full generality, any regular sequence in the different classes of promoters. One of the main findings of this analysis is that H. sapiens promoters can be classified into three main groups. Two of them are distinguished by the prevalence of weak or strong nucleotides and are characterized by short compositionally biased sequences, while the most frequent regular sequences in the third group are strongly correlated with transposons. Taking advantage of the generality of these mathematical procedures, we have compared the promoter database of H. sapiens with those of other species. We have found that the above-mentioned features characterize also the evolutionary content appearing in mammalian promoters, at variance with ancestral species in the phylogenetic tree, that exhibit a definitely lower level of differentiation among promoters.
Collapse
|
10
|
Mallatt J, Chittenden KD. The GC content of LSU rRNA evolves across topological and functional regions of the ribosome in all three domains of life. Mol Phylogenet Evol 2014; 72:17-30. [PMID: 24394731 DOI: 10.1016/j.ympev.2013.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 11/28/2013] [Accepted: 12/24/2013] [Indexed: 12/21/2022]
Abstract
Large-subunit rRNA is the ribozyme that catalyzes protein synthesis by translation, and many of its features vary along a deep-to-superficial gradient. By measuring the G+C proportions in this rRNA in all three domains of life (60 bacteria, 379 eukaryote, and 23 archaean sequences), we tested whether the proportion of GC nucleotides varies along this in-out gradient. The rRNA regions used were several zones identified by Bokov and Steinberg (2009) as being arranged from deep to superficial within the LSU. To the Bokov-Steinberg zones, we added the most superficial zone of all, the divergent domains (expansion segments), which are greatly enlarged in eukaryotes. Regression lines constructed from the hundreds of species of organisms revealed the expected in-out gradient, showing that species with high %GC (or high %AT) in their rRNA distribute more of these abundant nucleotides into the peripheral zones. This could be explained by the evolutionary rates of replacement of all nucleotides (A, C, G, T), because these latter rates are fastest at the periphery and slowest near the conserved core. As an overall explanation, we propose that when extrinsic factors (whole-genome nucleotide composition, or environmental temperature) demand the percentage of GC in the rRNA of a species be high or low, then the deep-lying zones are buffered against GC variation because they are the slowest to evolve. The deep, conserved zones are also the most involved in translation, hinting that stabilizing selection there prevents a high GC variability that would diminish LSU rRNA's core functions. We found only a few domain-specific trends in rRNA-GC distribution, which relate to many Archaea living at high temperatures or to the highly complex genes and adaptations of Eukaryota. Use of rRNA sequences in molecular phylogenetic studies, for reconstructing the relationships of organisms across the tree of life, requires accurate models of how rRNA evolves. The demonstration that GC distributes in regular patterns across rRNA regions can improve these tree-reconstruction models in the future and should yield phylogenies of greater accuracy.
Collapse
Affiliation(s)
- Jon Mallatt
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, United States.
| | - Kevin D Chittenden
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, United States
| |
Collapse
|
11
|
Gromak N, Dienstbier M, Macias S, Plass M, Eyras E, Cáceres JF, Proudfoot NJ. Drosha regulates gene expression independently of RNA cleavage function. Cell Rep 2013; 5:1499-510. [PMID: 24360955 PMCID: PMC3898267 DOI: 10.1016/j.celrep.2013.11.032] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 09/13/2013] [Accepted: 11/15/2013] [Indexed: 12/21/2022] Open
Abstract
Drosha is the main RNase III-like enzyme involved in the process of microRNA (miRNA) biogenesis in the nucleus. Using whole-genome ChIP-on-chip analysis, we demonstrate that, in addition to miRNA sequences, Drosha specifically binds promoter-proximal regions of many human genes in a transcription-dependent manner. This binding is not associated with miRNA production or RNA cleavage. Drosha knockdown in HeLa cells downregulated nascent gene transcription, resulting in a reduction of polyadenylated mRNA produced from these gene regions. Furthermore, we show that this function of Drosha is dependent on its N-terminal protein-interaction domain, which associates with the RNA-binding protein CBP80 and RNA Polymerase II. Consequently, we uncover a previously unsuspected RNA cleavage-independent function of Drosha in the regulation of human gene expression. Drosha binds promoter-proximal regions of transcribed human genes Drosha binding is not associated with RNA cleavage or miRNA processing Drosha regulates nascent gene transcription Drosha interacts with CBP80 and RNA Pol II through its N-terminal domain
Collapse
Affiliation(s)
- Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
| | - Martin Dienstbier
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Sara Macias
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - Mireya Plass
- Computational Genomics Group, Universitat Pompeu Fabra, Dr. Aiguader 88, 08003 Barcelona, Spain; The Bioinformatics Centre, Department of Biology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Eduardo Eyras
- Computational Genomics Group, Universitat Pompeu Fabra, Dr. Aiguader 88, 08003 Barcelona, Spain; Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Javier F Cáceres
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
| | - Nicholas J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
| |
Collapse
|
12
|
Arakawa K, Tomita M. Measures of compositional strand bias related to replication machinery and its applications. Curr Genomics 2012; 13:4-15. [PMID: 22942671 PMCID: PMC3269016 DOI: 10.2174/138920212799034749] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 09/10/2011] [Accepted: 09/20/2011] [Indexed: 11/22/2022] Open
Abstract
The compositional asymmetry of complementary bases in nucleotide sequences implies the existence of a mutational or selectional bias in the two strands of the DNA duplex, which is commonly shaped by strand-specific mechanisms in transcription or replication. Such strand bias in genomes, frequently visualized by GC skew graphs, is used for the computational prediction of transcription start sites and replication origins, as well as for comparative evolutionary genomics studies. The use of measures of compositional strand bias in order to quantify the degree of strand asymmetry is crucial, as it is the basis for determining the applicability of compositional analysis and comparing the strength of the mutational bias in different biological machineries in various species. Here, we review the measures of strand bias that have been proposed to date, including the ∆GC skew, the B1 index, the predictability score of linear discriminant analysis for gene orientation, the signal-to-noise ratio of the oligonucleotide bias, and the GC skew index. These measures have been predominantly designed for and applied to the analysis of replication-related mutational processes in prokaryotes, but we also give research examples in eukaryotes.
Collapse
Affiliation(s)
- Kazuharu Arakawa
- Institute for Advanced Biosciences, Keio University, Fujisawa 252-8520, Japan
| | | |
Collapse
|
13
|
Comments on: Some recent theory for autoregressive count time series. TEST-SPAIN 2012. [DOI: 10.1007/s11749-012-0298-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
14
|
Genomic, proteomic and physiological characterization of a T5-like bacteriophage for control of Shiga toxin-producing Escherichia coli O157:H7. PLoS One 2012; 7:e34585. [PMID: 22514640 PMCID: PMC3326045 DOI: 10.1371/journal.pone.0034585] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 03/07/2012] [Indexed: 11/19/2022] Open
Abstract
Despite multiple control measures, Escherichia coli O157:H7 (STEC O157:H7) continues to be responsible for many food borne outbreaks in North America and elsewhere. Bacteriophage therapy may prove useful for controlling this pathogen in the host, their environment and food. Bacteriophage vB_EcoS_AKFV33 (AKFV33), a T5-like phage of Siphoviridae lysed common phage types of STEC O157:H7 and not non-O157 E. coli. Moreover, STEC O157:H7 isolated from the same feedlot pen from which the phage was obtained, were highly susceptible to AKFV33. Adsorption rate constant and burst size were estimated to be 9.31 × 10(-9) ml/min and 350 PFU/infected cell, respectively. The genome of AKVF33 was 108,853 bp (38.95% G+C), containing 160 open reading frames (ORFs), 22 tRNA genes and 32 strong promoters recognized by host RNA polymerase. Of 12 ORFs without homologues to T5-like phages, 7 predicted novel proteins while others exhibited low identity (<60%) to proteins in the National Centre for Biotechnology Information database. AKVF33 also lacked the L-shaped tail fiber protein typical of T5, but was predicted to have tail fibers comprised of 2 novel proteins with low identity (37-41%) to tail fibers of E. coli phage phiEco32 of Podoviridae, a putative side tail fiber protein of a prophage from E. coli IAI39 and a conserved domain protein of E. coli MS196-1. The receptor-binding tail protein (pb5) shared an overall identify of 29-72% to that of other T5-like phages, with no region coding for more than 6 amino acids in common. Proteomic analysis identified 4 structural proteins corresponding to the capsid, major tail, tail fiber and pore-forming tail tip (pb2). The genome of AKFV33 lacked regions coding for known virulence factors, integration-related proteins or antibiotic resistance determinants. Phage AKFV33 is a unique, highly lytic STEC O157:H7-specific T5-like phage that may have considerable potential as a pre- and post-harvest biocontrol agent.
Collapse
|