Genome Sequence of the Nonpathogenic Listeria monocytogenes Serovar 4a Strain M7

Chen, Jianshun; Xia, Ye; Cui, Cheng; Fang, Chun; Shan, Ying; Jin, Gulei; Fang, Weihuan

doi:10.1128/jb.05501-11

Cited by 25 publications

(26 citation statements)

References 18 publications

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“…The genomes of several strains of L. monocytogenes have been sequenced in recent years (9,(19)(20)(21)(22). At present, there are 34 L. monocytogenes genomes publicly available, of which 16 are finished and 18 are available as draft sequences.…”

mentioning

confidence: 99%

Genome Sequencing Identifies Two Nearly Unchanged Strains of Persistent Listeria monocytogenes Isolated at Two Different Fish Processing Plants Sampled 6 Years Apart

Holch

Webb

Lukjancenko

et al. 2013

Appl Environ Microbiol

117

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Listeria monocytogenes is a food-borne human-pathogenic bacterium that can cause infections with a high mortality rate. It has a remarkable ability to persist in food processing facilities. Here we report the genome sequences for two L. monocytogenes strains (N53-1 and La111) that were isolated 6 years apart from two different Danish fish processers. Both strains are of serotype 1/2a and belong to a highly persistent DNA subtype (random amplified polymorphic DNA [RAPD] type 9). We demonstrate using in silico analyses that both strains belong to the multilocus sequence typing (MLST) type ST121 that has been isolated as a persistent subtype in several European countries. The purpose of this study was to use genome analyses to identify genes or proteins that could contribute to persistence. In a genome comparison, the two persistent strains were extremely similar and collectively differed from the reference lineage II strain, EGD-e. Also, they differed markedly from a lineage I strain (F2365). On the proteome level, the two strains were almost identical, with a predicted protein homology of 99.94%, differing at only 2 proteins. No single-nucleotide polymorphism (SNP) differences were seen between the two strains; in contrast, N53-1 and La111 differed from the EGD-e reference strain by 3,942 and 3,471 SNPs, respectively. We included a persistent L. monocytogenes strain from the United States (F6854) in our comparisons. Compared to nonpersistent strains, all three persistent strains were distinguished by two genome deletions: one, of 2,472 bp, typically contains the gene for inlF, and the other, of 3,017 bp, includes three genes potentially related to bacteriocin production and transport (lmo2774, lmo2775, and the 3=-terminal part of lmo2776). Further studies of highly persistent strains are required to determine if the absence of these genes promotes persistence. While the genome comparison did not point to a clear physiological explanation of the persistent phenotype, the remarkable similarity between the two strains indicates that subtypes with specific traits are selected for in the food processing environment and that particular genetic and physiological factors are responsible for the persistent phenotype. Listeria monocytogenes is a Gram-positive, food-borne, humanpathogenic bacterium that can cause listeriosis in humans. It affects predominantly immunocompromised individuals, the elderly, young babies, and fetuses in utero (1). Although listeriosis represents only 7.4% of all reported food-borne infections, the fatality rate (17%) and hospitalization rates (92.6%) are high (2).The bacterium is common in food products and poses a special risk in ready-to-eat products that allow proliferation of the pathogen. It is not only a safety issue but also an economic concern, because 61% of food products recalled by the U.S. FDA between 1994 and 1998 were due to L. monocytogenes contamination (3). The bacterium is an intracellular human pathogen, and it also has a saprophytic life-style and can therefore be isolated fr...

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confidence: 99%

Genome Sequencing Identifies Two Nearly Unchanged Strains of Persistent Listeria monocytogenes Isolated at Two Different Fish Processing Plants Sampled 6 Years Apart

Holch

Webb

Lukjancenko

et al. 2013

Appl Environ Microbiol

117

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“…We found that the M7 strain had apparent phospholipase activity due to high-level expression of PlcB, probably as a result of constitutive activation of PrfA (Chen et al, 2011b). Transcription levels of major PrfA-regulated genes in M7 were higher than in EGDe, both in broth media and in whole blood, while M7 did not cause any lethality to mice and its load in the liver and spleen was far lower than for EGDe.…”

Section: Defects Of the M7 Strain In Virulence-related Phenotypesmentioning

confidence: 86%

“…Sequence analysis has shown that PrfA of the serovar 4a strain M7 from milk has three amino acids (Ser145, Ala165 and Asn197) different from those of EGDe (Gly145, Thr165 and Lys197) (Chen et al, 2011b), indicating that the PrfA of M7 could be constitutively active for transcriptional regulation, seen as strong phospholipase and haemolytic activities (Ripio et al, 1997;Vega et al, 2004;Wong & Freitag, 2004). Transcriptional analysis of PrfA-regulated genes in BHI medium and whole sheep blood showed that M7 did have a significantly higher expression than EGDe (Pv0.01) (Fig.…”

Section: Prfa Of the Low-virulence Strain M7 Was Constitutively Activmentioning

confidence: 99%

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Activation of PrfA results in overexpression of virulence factors but does not rescue the pathogenicity of Listeria monocytogenes M7

Fang

Cao

Cui

et al. 2015

Journal of Medical Microbiology

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Listeria monocytogenes encodes a transcriptional activator, PrfA, to positively regulate the expression of virulence factors. Several mutations in PrfA (PrfA * ) have been found to contribute to increased regulatory activity. Here, we describe a strain, M7, containing a PrfA * (G145S) that activates expression of virulence factors but with low pathogenicity. To study this contradictory relationship, we exchanged the prfA genes between strains EGDe and M7 (designated EGDe-prfA M7 and M7-prfA EGDe ). The phospholipase B (PlcB) and listeriolysin O (LLO) activities were significantly upregulated in the strain EGDe-prfA M7 (PrfA*). Constitutive activation of PrfA potentiated virulence of the pathogenic strain EGDe, shown as increased adhesion and invasion as well as enhanced cell-to-cell spread in cultured cell lines. However, the strain M7, though PrfA-activated, had significant defects in these virulence-related phenotypes and low pathogenicity in the murine infection model, as compared with EGDe or EGDe-PrfA M7 . To further uncover the possible mechanisms, we analysed abundance and distributions of InlA, InlB, LLO and ActA proteins, all regulated by PrfA, in EGDe, M7 and their prfA mutants. Western blotting showed that the PrfA-regulated genes of constitutively activated PrfA strains were overexpressed in vitro, while different distributions were observed. In contrast to the virulent strain EGDe-prfA M7 , the majority of InlB in M7 was detected in the culture supernatant and not on the bacterial surface. We suppose that the low virulence of strain M7 is due to its defects in infecting host cells, possibly as a result of failed anchorage on the bacterial cells of surface proteins like InlB, a major protein involved in adhesion and invasion of pathogenic L. monocytogenes strains. Further research is warranted to address why InlB detaches from the bacterial cells of this particular strain.

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“…Leuconostoc pseudomesenteroides KCTC 3652, sequence accession AEOQ00000001 through AEOQ00001160 [61] Lactobacillus mali KCTC 3596, sequence accession BACP01000001 through BACP01000122 [62] Paenibacillus polymyxa Type Strain ATCC 842 T , sequence accession AFOX01000000 [63] Streptococcus salivarius strain JIM8777, sequence accssion FR873482 [64] Lactobacillus cypricasei KCTC 13900, sequence accession BACS01000001 to BACS01000487 [65] Lactobacillus zeae KCTC 3804, sequence accession BACQ01000001 to BACQ101000113 [66] Listeria monocytogenes Serovar 4a Strain M7, sequence accession CP002816 [67] Lactobacillus salivarius GJ-24, sequence accession AFOI00000000 [68] Lactobacillus johnsonii PF01, sequence accession AFQJ01000000 [69] Clostridium acetobutylicum DSM 1731, sequence accession CP002660 through CP002662 [70] Lactobacillus suebicus KCTC 3549, sequence accession BACO01000000 [71] Brevibacillus laterosporus LMG 15441, sequence accession AFRV00000000 [72] Lactobacillus salivarius NIAS840, sequence accession AFMN00000000 [73] Bifidobacterium animalis subsp. lactis CNCM I-2494, sequence accession CP002915 [74] Megasphaera elsdenii, sequence accession HE576794 [75] Lactobacillus versmoldensis KCTC 3814, sequence accession BACR01000001 to BACR01000102 [76] Lactobacillus pentosus IG1, sequence accession FR874848 to FR874860 [77] Alicyclobacillus acidocaldarius Strain Tc-4-1, sequence accession CP002902 [78] Streptococcus thermophilus Strain JIM8232, sequence accession FR875178 [79] Streptococcus equi subsp.…”

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confidence: 99%

Genome sequences of Bacteria and Archaea published outside of Standards in Genomic Sciences, June – September 2011

Nelson

2011

Stand. Genomic Sci.

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Genome Sequence of the Nonpathogenic Listeria monocytogenes Serovar 4a Strain M7

Abstract: This report presents the complete and annotated genome sequence of the naturally nonpathogenic Listeria monocytogenes serovar 4a strain M7, isolated from cow's milk in Zhejiang province, China.

Cited by 25 publications

References 18 publications

Genome Sequencing Identifies Two Nearly Unchanged Strains of Persistent Listeria monocytogenes Isolated at Two Different Fish Processing Plants Sampled 6 Years Apart

Genome Sequencing Identifies Two Nearly Unchanged Strains of Persistent Listeria monocytogenes Isolated at Two Different Fish Processing Plants Sampled 6 Years Apart

Activation of PrfA results in overexpression of virulence factors but does not rescue the pathogenicity of Listeria monocytogenes M7

Genome sequences of Bacteria and Archaea published outside of Standards in Genomic Sciences, June – September 2011

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