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Hu D.,Nankai University | Liu B.,Nankai University | Liu B.,The Key Laboratory of Molecular Microbiology and Technology | Dijkshoorn L.,Leiden University | And 4 more authors.
PLoS ONE | Year: 2013

We have sequenced the gene clusters for type strains of the Acinetobacter baumannii serotyping scheme developed in the 1990s, and used the sequences to better understand diversity in surface polysaccharides of the genus. We obtained genome sequences for 27 available serovar type strains, and identified 25 polysaccharide gene cluster sequences. There are structures for 12 of these polysaccharides, and in general the genes present are appropriate to the structure where known. This greatly facilitates interpretation. We also find 53 different glycosyltransferase genes, and for 7 strains can provisionally allocate specific genes to all linkages. We identified primers that will distinguish the 25 sequence forms by PCR or microarray, or alternatively the genes can be used to determine serotype by "molecular serology". We applied the latter to 190 Acinetobacter genome-derived gene-clusters, and found 76 that have one of the 25 gene-cluster forms. We also found novel gene clusters and added 52 new gene-cluster sequence forms with different wzy genes and different gene contents. Altogether, the strains that have one of the original 25 sequence forms include 98 A. baumannii (24 from our strains) and 5 A. nosocomialis (3 from our strains), whereas 32 genomes from 12 species other than A. baumannii or A. nosocomialis, all have new sequence forms. One of the 25 serovar type sequences is found to be in European clone I (EC I), 2 are in EC II but none in EC III. The public genome strains add an additional 52 new sequence forms, and also bring the number found in EC I to 5, in EC II to 9 and in EC III to 2. © 2013 Hu et al.


Wang L.,Nankai University | Spira B.,University of Sao Paulo | Spira B.,University of New South Wales | Zhou Z.,Nankai University | And 10 more authors.
Genome Biology and Evolution | Year: 2010

Many of the important changes in evolution are regulatory in nature. Sequenced bacterial genomes point to flexibility in regulatory circuits but we do not know how regulation is remodeled in evolving bacteria. Here, we study the regulatory changes that emerge in populations evolving under controlled conditions during experimental evolution of Escherichia coli in a phosphate-limited chemostat culture. Genomes were sequenced from five clones with different combinations of phenotypic properties that coexisted in a population after 37 days. Each of the distinct isolates contained a different mutation in 1 of 3 highly pleiotropic regulatory genes (hfq, spoT, or rpoS). The mutations resulted in dissimilar proteomic changes, consistent with the documented effects of hfq, spoT, and rpoS mutations. The different mutations do share a common benefit, however, in that the mutations each redirect cellular resources away from stress responses that are redundant in a constant selection environment. The hfq mutation lowers several individual stress responses as well the small RNA-dependent activation of rpoS translation and hence general stress resistance. The spoT mutation reduces ppGpp levels, decreasing the stringent response as well as rpoS expression. The mutations in and upstream of rpoS resulted in partial or complete loss of general stress resistance. Our observations suggest that the degeneracy at the core of bacterial stress regulation provides alternative solutions to a common evolutionary challenge. These results can explain phenotypic divergence in a constant environment and also how evolutionary jumps and adaptive radiations involve altered gene regulation. © The Author(s) 2010.


Maharjan R.,University of Sydney | Zhou Z.,Nankai University | Zhou Z.,Tianjin Key Laboratory of Microbial Functional Genomics | Ren Y.,Nankai University | And 13 more authors.
Journal of Bacteriology | Year: 2010

Beneficial mutations in diversifying glucose-limited Escherichia coli populations are mostly unidentified. The genome of an evolved isolate with multiple differences from that of the ancestor was fully assembled. Remarkably, a single mutation in hfq was responsible for the multiple benefits under glucose limitation through changes in at least five regulation targets. Copyright © 2010, American Society for Microbiology. All Rights Reserved.


Liu B.,Nankai University | Liu B.,The Key Laboratory of Molecular Microbiology and Technology | Knirel Y.A.,RAS N. D. Zelinsky Institute of Organic Chemistry | Feng L.,Nankai University | And 9 more authors.
FEMS Microbiology Reviews | Year: 2014

This review covers the structures and genetics of the 46 O antigens of Salmonella, a major pathogen of humans and domestic animals. The variation in structures underpins the serological specificity of the 46 recognized serogroups. The O antigen is important for the full function and virulence of many bacteria, and the considerable diversity of O antigens can confer selective advantage. Salmonella O antigens can be divided into two major groups: those which have N-acetylglucosamine (GlcNAc) or N-acetylgalactosamine (GalNAc) and those which have galactose (Gal) as the first sugar in the O unit. In recent years, we have determined 21 chemical structures and sequenced 28 gene clusters for GlcNAc-/GalNAc-initiated O antigens, thus completing the structure and DNA sequence data for the 46 Salmonella O antigens. The structures and gene clusters of the GlcNAc-/GalNAc-initiated O antigens were found to be highly diverse, and 24 of them were found to be identical or closely related to Escherichia coli O antigens. Sequence comparisons indicate that all or most of the shared gene clusters were probably present in the common ancestor, although alternative explanations are also possible. In contrast, the better-known eight Gal-initiated O antigens are closely related both in structures and gene cluster sequences. In this review, we systematically analyzed and summarized Salmonella O-antigen diversity including the chemical structures, gene cluster sequences, and evolutionary aspects. © 2013 Federation of European Microbiological Societies.


Wang L.,Chinese Academy of Agricultural Sciences | Wang L.,Nankai University | Wang L.,Tianjin Research Center for Functional Genomics and Biochip | Yuan T.,Chinese Academy of Agricultural Sciences | And 11 more authors.
Applied Microbiology and Biotechnology | Year: 2011

Xylose is the second most abundant lignocellulosic component besides glucose, but it cannot be fermented by the widely used ethanol-producing yeast Saccharomyces cerevisiae. The yeast Scheffersomyces stipitis, however, is well known for its high native capacity to ferment xylose. Here, we applied next-generation sequencing technology for RNA (RNA-Seq) to generate two high-resolution transcriptional maps of the S. stipitis genome when this yeast was grown using glucose or xylose as the sole carbon source. RNA-Seq revealed that 5,176 of 5,816 annotated open reading frames had a uniform transcription and that 214 open reading frames were differentially transcribed. Differential expression analysis showed that, compared with other biological processes, carbohydrate metabolism and oxidation-reduction reactions were highly enhanced in yeast grown on xylose. Measurement of metabolic indicators of fermentation showed that, in yeast grown on xylose, the concentrations of cysteine and ornithine were twofold higher and the concentrations of unsaturated fatty acids were also increased. Analysis of metabolic profiles coincided with analysis of certain differentially expressed genes involved in metabolisms of amino acid and fatty acid. In addition, we predicted protein-protein interactions of S. stipitis through integration of gene orthology and gene expression. Further analysis of metabolic and protein-protein interactions networks through integration of transcriptional and metabolic profiles predicted correlations of genes involved in glycolysis, the tricarboxylic acid cycle, gluconeogenesis, sugar uptake, amino acid metabolism, and fatty acid β-oxidation. Our study reveals potential target genes for xylose fermentation improvement and provides insights into the mechanisms underlying xylose fermentation in S. stipitis. © 2011 Springer-Verlag.


Reeves P.R.,University of Sydney | Liu B.,Nankai University | Liu B.,The Key Laboratory of Molecular Microbiology and Technology | Zhou Z.,Nankai University | And 13 more authors.
PLoS ONE | Year: 2011

Although over 50 complete Escherichia coli/Shigella genome sequences are available, it is only for closely related strains, for example the O55:H7 and O157:H7 clones of E. coli, that we can assign differences to individual evolutionary events along specific lineages. Here we sequence the genomes of 14 isolates of a uropathogenic E. coli clone that persisted for 3 years within a household, including a dog, causing a urinary tract infection (UTI) in the dog after 2 years. The 20 mutations observed fit a single tree that allows us to estimate the mutation rate to be about 1.1 per genome per year, with minimal evidence for adaptive change, including in relation to the UTI episode. The host data also imply at least 6 host transfer events over the 3 years, with 2 lineages present over much of that period. To our knowledge, these are the first direct measurements for a clone in a well-defined host community that includes rates of mutation and host transmission. There is a concentration of non-synonymous mutations associated with 2 transfers to the dog, suggesting some selection pressure from the change of host. However, there are no changes to which we can attribute the UTI event in the dog, which suggests that this occurrence after 2 years of the clone being in the household may have been due to chance, or some unknown change in the host or environment. The ability of a UTI strain to persist for 2 years and also to transfer readily within a household has implications for epidemiology, diagnosis, and clinical intervention. © 2011 Reeves et al.


Chen C.,Jiangnan University | Zhou Z.,Nankai University | Wang L.,Tianjin Research Center for Functional Genomics and Biochip | Zhang H.,Jiangnan University | Chen W.,Jiangnan University
Journal of Bacteriology | Year: 2011

Lactobacillus plantarum strain ST-III, a probiotic strain with several functions, was isolated from kimchi. Here we report the complete genome sequence of ST-III and compared it with two published L. plantarum genomes. Copyright © 2011, American Society for Microbiology. All Rights Reserved.


Cunneen M.M.,University of Sydney | Liu B.,Nankai University | Liu B.,Tianjin Research Center for Functional Genomics and Biochip | Wang L.,Nankai University | And 2 more authors.
PLoS ONE | Year: 2013

We have undertaken an extensive survey of a group of epimerases originally named Gne, that were thought to be responsible for inter-conversion of UDP-N-acetylglucosamine (UDP-GlcNAc) and UDP-N-acetylgalactosamine (UDP-GalNAc). The analysis builds on recent work clarifying the specificity of some of these epimerases. We find three well defined clades responsible for inter-conversion of the gluco- and galacto-configuration at C4 of different N-acetylhexosamines. Their major biological roles are the formation of UDP-GalNAc, UDP-N-acetylgalactosaminuronic acid (UDP-GalNAcA) and undecaprenyl pyrophosphate-N-acetylgalactosamine (UndPP-GalNAc) from the corresponding glucose forms. We propose that the clade of UDP-GlcNAcA epimerase genes be named gnaB and the clade of UndPP-GlcNAc epimerase genes be named gnu, while the UDP-GlcNAc epimerase genes retain the name gne. The Gne epimerases, as now defined after exclusion of those to be named GnaB or Gnu, are in the same clade as the GalE 4-epimerases for inter-conversion of UDP-glucose (UDP-Glc) and UDP-galactose (UDP-Gal). This work brings clarity to an area that had become quite confusing. The identification of distinct enzymes for epimerisation of UDP-GlcNAc, UDP-GlcNAcA and UndPP-GlcNAc will greatly facilitate allocation of gene function in polysaccharide gene clusters, including those found in bacterial genome sequences. A table of the accession numbers for the 295 proteins used in the analysis is provided to enable the major tree to be regenerated with the inclusion of additional proteins of interest. This and other suggestions for annotation of 4-epimerase genes will facilitate annotation. © 2013 Cunneen et al.


Zhou Z.,Nankai University | Zhou Z.,Tianjin Research Center for Functional Genomics and Biochip | Li X.,Nankai University | Liu B.,Nankai University | And 10 more authors.
PLoS ONE | Year: 2010

There are 29 E. coli genome sequences available, mostly related to studies of species diversity or mode of pathogenicity, including two genomes of the well-known O157:H7 clone. However, there have been no genome studies of closely related clones aimed at exposing the details of evolutionary change. Here we sequenced the genome of an O55:H7 strain, closely related to the major pathogenic O157:H7 clone, with published genome sequences, and undertook comparative genomic and proteomic analysis. We were able to allocate most differences between the genomes to individual mutations, recombination events, or lateral gene transfer events, in specific lineages. Major differences include a type II secretion system present only in the O55:H7 chromosome, fewer type III secretion system effectors in O55:H7, and 19 phage genomes or phagelike elements in O55:H7 compared to 23 in O157:H7, with only three common to both. Many other changes were found in both O55:H7 and O157:H7 lineages, but in general there has been more change in the O157:H7 lineages. For example, we found 50% more synonymous mutational substitutions in O157:H7 compared to O55:H7. The two strains also diverged at the proteomic level. Mutational synonymous SNPs were used to estimate a divergence time of 400 years using a new clock rate, in contrast to 14,000 to 70,000 years using the traditional clock rates. The same approaches were applied to three closely related extraintestinal pathogenic E. coli genomes, and similar levels of mutation and recombination were found. This study revealed for the first time the full range of events involved in the evolution of the O157:H7 clone from its O55:H7 ancestor, and suggested that O157:H7 arose quite recently. Our findings also suggest that E. coli has a much lower frequency of recombination relative to mutation than was observed in a comparable study of a Vibrio cholerae lineage. © 2010 Zhou et al.


Zhu H.,Nankai University | Zhu H.,Key Laboratory of Molecular Microbiology and Technology | Wang Q.,Nankai University | Wang Q.,Key Laboratory of Molecular Microbiology and Technology | And 12 more authors.
Journal of Clinical Microbiology | Year: 2012

Neisseria meningitidis is a leading pathogen of epidemic bacterial meningitis and fulminant sepsis worldwide. Twelve different N. meningitidis serogroups have been identified to date based on antigenic differences in the capsular polysaccharide. However, more than 90% of human cases of N. meningitidis meningitis are the result of infection with just five serogroups, A, B, C, W135, and Y. Efficient methods of detection and genogrouping of N. meningitidis isolates are needed, therefore, in order to monitor prevalent serogroups as a means of disease control and prevention. The capsular gene complex regions have been sequenced from only seven out of the 12 serogroups. In this study, the capsular gene complexes of the remaining five serogroups were sequenced and analyzed. Primers were designed that were specific for N. meningitidis species and for the 12 individual serogroups, and a multiplex PCR assay using these specific primers was developed for N. meningitidis detection and genogrouping. The assay was tested using 15 reference strains covering all 12 serogroups, 143 clinical isolates, and 21 strains from closely related species or from species that cause meningitis. The assay could detect N. meningitidis serogroups and was shown to be specific, with a detection sensitivity of 1 ng of genomic DNA (equivalent to ∼4 × 10 5 genomes) or 3 × 10 5 CFU/ml in noncultured mock cerebrospinal fluid (CSF) specimens. This study, therefore, describes for the first time the development of a molecular protocol for the detection of all N. meningitidis serogroups. This multiplex PCR-based assay may have use for the clinical diagnosis and epidemiological surveillance of N. meningitidis. Copyright © 2012, American Society for Microbiology. All Rights Reserved.

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