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Asset Tag: methylome

July 7, 2019

Identification of IncA/C plasmid replication and maintenance genes and development of a plasmid multilocus sequence typing scheme.

Plasmids of incompatibility group A/C (IncA/C) are becoming increasingly prevalent within pathogenic Enterobacteriaceae They are associated with the dissemination of multiple clinically relevant resistance genes, including blaCMY and blaNDM Current typing methods for IncA/C plasmids offer limited resolution. In this study, we present the complete sequence of a blaNDM-1-positive IncA/C plasmid, pMS6198A, isolated from a multidrug-resistant uropathogenic Escherichia coli strain. Hypersaturated transposon mutagenesis, coupled with transposon-directed insertion site sequencing (TraDIS), was employed to identify conserved genetic elements required for replication and maintenance of pMS6198A. Our analysis of TraDIS data identified roles for the replicon, including repA, a toxin-antitoxin system; two putative partitioning genes, parAB; and a putative gene, 053 Construction of mini-IncA/C plasmids and examination of their stability within E. coli confirmed that the region encompassing 053 contributes to the stable maintenance of IncA/C plasmids. Subsequently, the four major maintenance genes (repA, parAB, and 053) were used to construct a new plasmid multilocus sequence typing (PMLST) scheme for IncA/C plasmids. Application of this scheme to a database of 82 IncA/C plasmids identified 11 unique sequence types (STs), with two dominant STs. The majority of blaNDM-positive plasmids examined (15/17; 88%) fall into ST1, suggesting acquisition and subsequent expansion of this blaNDM-containing plasmid lineage. The IncA/C PMLST scheme represents a standardized tool to identify, track, and analyze the dissemination of important IncA/C plasmid lineages, particularly in the context of epidemiological studies. Copyright © 2017 American Society for Microbiology.

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July 7, 2019

Genomic analysis of ST88 community-acquired methicillin resistant Staphylococcus aureus in Ghana.

The emergence and evolution of community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) strains in Africa is poorly understood. However, one particular MRSA lineage called ST88, appears to be rapidly establishing itself as an “African” CA-MRSA clone. In this study, we employed whole genome sequencing to provide more information on the genetic background of ST88 CA-MRSA isolates from Ghana and to describe in detail ST88 CA-MRSA isolates in comparison with other MRSA lineages worldwide.We first established a complete ST88 reference genome (AUS0325) using PacBio SMRT sequencing. We then used comparative genomics to assess relatedness among 17 ST88 CA-MRSA isolates recovered from patients attending Buruli ulcer treatment centres in Ghana, three non-African ST88s and 15 other MRSA lineages.We show that Ghanaian ST88 forms a discrete MRSA lineage (harbouring SCCmec-IV [2B]). Gene content analysis identified five distinct genomic regions enriched among ST88 isolates compared with the other S. aureus lineages. The Ghanaian ST88 isolates had only 658 core genome SNPs and there was no correlation between phylogeny and geography, suggesting the recent spread of this clone. The lineage was also resistant to multiple classes of antibiotics including ß-lactams, tetracycline and chloramphenicol.This study reveals that S. aureus ST88-IV is a recently emerging and rapidly spreading CA-MRSA clone in Ghana. The study highlights the capacity of small snapshot genomic studies to provide actionable public health information in resource limited settings. To our knowledge this is the first genomic assessment of the ST88 CA-MRSA clone.

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July 7, 2019

Free-living Enterobacterium Pragia fontium 24613: complete genome sequence and metabolic profiling.

Pragia fontium is one of the few species that belongs to the group of atypical hydrogen sulfide-producing enterobacteria. Unlike other members of this closely related group, P. fontium is not associated with any known host and has been reported as a free-living bacterium. Whole genome sequencing and metabolic fingerprinting confirmed the phylogenetic position of P. fontium inside the group of atypical H2S producers. Genomic data have revealed that P. fontium 24613 has limited pathogenic potential, although there are signs of genome decay. Although the lack of specific virulence factors and no association with a host species suggest a free-living style, the signs of genome decay suggest a process of adaptation to an as-yet-unknown host.

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July 7, 2019

Large scale and significant expression from pseudogenes in Sodalis glossinidius – a facultative bacterial endosymbiont

The majority of bacterial genomes have high coding efficiencies, but there are some genomes of intracellular bacteria that have low gene density. The genome of the endosymbiont Sodalis glossinidius contains almost 50% pseudogenes containing mutations that putatively silence them at the genomic level. We have applied multiple omic strategies, combining: Illumina and Pacific Biosciences Single-Molecule Real Time DNA-sequencing and annotation; stranded RNA-sequencing; and proteome analysis to better understand the transcriptional and translational landscape of Sodalis pseudogenes, and potential mechanisms for their control. Between 53% and 74% of the Sodalis transcriptome remains active in cell-free culture. Mean sense transcription from Coding Domain Sequences (CDS) is four-times greater than that from pseudogenes. Comparative genomic analysis of six Illumina-sequenced Sodalis isolates from different host Glossina species shows pseudogenes make up ~40% of the 2,729 genes in the core genome, suggesting are stable and/or Sodalis is a recent introduction across the Glossina genus as a facultative symbiont. These data further shed light on the importance of transcriptional and translational control in deciphering host-microbe interactions, and demonstrate that pseudogenes are more complex than a simple degrading DNA sequence. The combination of genomics, transcriptomics and proteomics give a multidimensional perspective for studying prokaryotic genomes with a view to elucidating evolutionary adaptation to novel environmental niches.

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July 7, 2019

Methylomic and phenotypic analysis of the ModH5 phasevarion of Helicobacter pylori.

The Helicobacter pylori phase variable gene modH, typified by gene HP1522 in strain 26695, encodes a N6-adenosine type III DNA methyltransferase. Our previous studies identified multiple strain-specific modH variants (modH1 – modH19) and showed that phase variation of modH5 in H. pylori P12 influenced expression of motility-associated genes and outer membrane protein gene hopG. However, the ModH5 DNA recognition motif and the mechanism by which ModH5 controls gene expression were unknown. Here, using comparative single molecule real-time sequencing, we identify the DNA site methylated by ModH5 as 5′-Gm6ACC-3′. This motif is vastly underrepresented in H. pylori genomes, but overrepresented in a number of virulence genes, including motility-associated genes, and outer membrane protein genes. Motility and the number of flagella of H. pylori P12 wild-type were significantly higher than that of isogenic modH5 OFF or ?modH5 mutants, indicating that phase variable switching of modH5 expression plays a role in regulating H. pylori motility phenotypes. Using the flagellin A (flaA) gene as a model, we show that ModH5 modulates flaA promoter activity in a GACC methylation-dependent manner. These findings provide novel insights into the role of ModH5 in gene regulation and how it mediates epigenetic regulation of H. pylori motility.

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July 7, 2019

Complete genome sequence of Celeribacter marinus IMCC12053(T), the host strain of marine bacteriophage P12053L.

Isolated from coastal seawater from Yellow Sea of Korea, Celeribacter marinus IMCC12053 was used as the host bacterium for bacteriophage P12053L. Here we report the complete genome sequence of strain IMCC12053 for further study of the marine bacteriophage P12053L functional genes. Single molecule real-time technology (PacBio RSII) was used for the single circular chromosome that is 3,096,705 base pairs in length and the GC content is 56.24%. It contains 3155 ORFs with 45 tRNAs and 6 rRNAs genes. N(6)-methyladenosine patterns were also investigated for 32 unmethylated genes and intergenic regions that covered many regulators and phage genes as well as ribosomal RNA genes and tRNA genes. Cryptic N(4)-methylcytosine pattern was investigated to speculate GpC methylase activity throughout the genome. Comparative genomics with other Celeribacter genomes were carried out for polyaromatic hydrocarbon degradation, but there were no aromatic ring oxygenases in IMCC12053 when compared to Celeribacter indicus P73. Copyright © 2015 Elsevier B.V. All rights reserved.

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July 7, 2019

Complete genome sequence of the potato pathogen Ralstonia solanacearum UY031.

Ralstonia solanacearum is the causative agent of bacterial wilt of potato. Ralstonia solanacearum strain UY031 belongs to the American phylotype IIB, sequevar 1, also classified as race 3 biovar 2. Here we report the completely sequenced genome of this strain, the first complete genome for phylotype IIB, sequevar 1, and the fourth for the R. solanacearum species complex. In addition to standard genome annotation, we have carried out a curated annotation of type III effector genes, an important pathogenicity-related class of genes for this organism. We identified 60 effector genes, and observed that this effector repertoire is distinct when compared to those from other phylotype IIB strains. Eleven of the effectors appear to be nonfunctional due to disruptive mutations. We also report a methylome analysis of this genome, the first for a R. solanacearum strain. This analysis helped us note the presence of a toxin gene within a region of probable phage origin, raising the hypothesis that this gene may play a role in this strain’s virulence.

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July 7, 2019

Complete genome and methylome sequences of two Salmonella enterica spp.

Salmonella enterica is responsible for major foodborne outbreaks worldwide. It can cause gastroenteritis characterized by diarrhea, vomiting, and fever. Salmonella infections raise public health concerns along with consequential economic impacts. In this report, we announce the first complete genome sequences of Salmonella enterica subsp. enterica serovar Choleraeuis (S. Choleraeuis) ATCC 10708 and Salmonella enterica subsp. enterica serovar Pullorum (S. Pullorum) ATCC 9120, isolated from patients with diarrhea. Copyright © 2016 Yao et al.

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July 7, 2019

Complete genome sequence and comparative genomics of a novel Myxobacterium Myxococcus hansupus.

Myxobacteria, a group of Gram-negative aerobes, belong to the class d-proteobacteria and order Myxococcales. Unlike anaerobic d-proteobacteria, they exhibit several unusual physiogenomic properties like gliding motility, desiccation-resistant myxospores and large genomes with high coding density. Here we report a 9.5 Mbp complete genome of Myxococcus hansupus that encodes 7,753 proteins. Phylogenomic and genome-genome distance based analysis suggest that Myxococcus hansupus is a novel member of the genus Myxococcus. Comparative genome analysis with other members of the genus Myxococcus was performed to explore their genome diversity. The variation in number of unique proteins observed across different species is suggestive of diversity at the genus level while the overrepresentation of several Pfam families indicates the extent and mode of genome expansion as compared to non-Myxococcales d-proteobacteria.

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July 7, 2019

Complete genome and methylome sequences of Salmonella enterica subsp. enterica serovar Panama (ATCC 7378) and Salmonella enterica subsp. enterica serovar Sloterdijk (ATCC 15791).

Salmonella enterica spp. are pathogenic bacteria commonly associated with food-borne outbreaks in human and animals. Salmonella enterica spp. are characterized into more than 2,500 different serotypes, which makes epidemiological surveillance and outbreak control more difficult. In this report, we announce the first complete genome and methylome sequences from two Salmonella type strains associated with food-borne outbreaks, Salmonella enterica subsp. enterica serovar Panama (ATCC 7378) and Salmonella enterica subsp. enterica serovar Sloterdijk (ATCC 15791). Copyright © 2016 Yao et al.

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July 7, 2019

Complete genome sequence and methylome of Salmonella enterica subsp. enterica Cerro, a frequent dairy cow serovar.

Salmonella enterica subsp. enterica serovar Cerro is an infrequent pathogen of humans and other mammals but is frequently isolated from the hindgut of asymptomatic cattle in the United States. To further understand the genomic determinants of S. Cerro specificity for the bovine hindgut, the genome of isolate CFSAN001588 was fully sequenced and deposited in the GenBank database. Copyright © 2016 Haley et al.

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