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- Regulator of ribonuclease activity modulates the pathogenicity of Vibrio vulnificus
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Jaejin Lee , Eunkyoung Shin , Jaeyeong Park , Minho Lee , Kangseok Lee
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J. Microbiol. 2021;59(12):1133-1141. Published online November 9, 2021
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DOI: https://doi.org/10.1007/s12275-021-1518-5
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Abstract
- RraA, a protein regulator of RNase E activity, plays a unique
role in modulating the mRNA abundance in Escherichia coli.
The marine pathogenic bacterium Vibrio vulnificus also possesses
homologs of RNase E (VvRNase E) and RraA (VvRraA1
and VvRraA2). However, their physiological roles have not
yet been investigated. In this study, we demonstrated that
VvRraA1 expression levels affect the pathogenicity of V. vulnificus.
Compared to the wild-type strain, the VvrraA1-deleted
strain (ΔVvrraA1) showed decreased motility, invasiveness,
biofilm formation ability as well as virulence in mice; these
phenotypic changes of ΔVvrraA1 were restored by the exogenous
expression of VvrraA1. Transcriptomic analysis indicated
that VvRraA1 expression levels affect the abundance
of a large number of mRNA species. Among them, the halflives
of mRNA species encoding virulence factors (e.g., smcR
and htpG) that have been previously shown to affect VvrraA1
expression-dependent phenotypes were positively correlated
with VvrraA1 expression levels. These findings suggest that
VvRraA1 modulates the pathogenicity of V. vulnificus by regulating
the abundance of a subset of mRNA species.
- Characterization of a novel dsRNA mycovirus of Trichoderma atroviride NFCF377 reveals a member of “Fusagraviridae” with changes in antifungal activity of the host fungus
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Jeesun Chun , Byeonghak Na , Dae-Hyuk Kim
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J. Microbiol. 2020;58(12):1046-1053. Published online October 23, 2020
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DOI: https://doi.org/10.1007/s12275-020-0380-1
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Abstract
- Trichoderma atroviride is a common fungus found in various
ecosystems that shows mycoparasitic ability on other fungi.
A novel dsRNA virus was isolated from T. atroviride NFCF377
strain and its molecular features were analyzed. The viral
genome consists of a single segmented double-stranded RNA
and is 9,584 bp in length, with two discontinuous open reading
frames (ORF1 and ORF2). A mycoviral structural protein
and an RNA-dependent RNA polymerase (RdRp) are encoded
by ORF1 and ORF2, respectively, between which is found a
canonical shifty heptameric signal motif (AAAAAAC) followed
by an RNA pseudoknot. Analysis of sequence similarity
and phylogeny showed that it is closely related to members
of the proposed family “Fusagraviridae”, with a highest similarity
to the Trichoderma atroviride mycovirus 1 (TaMV1).
Although the sequence similarity of deduced amino acid to
TaMV1 was evident, sequence deviations were distinctive at
untranslated regions (UTRs) due to the extended size. Thus,
we inferred this dsRNA to be a different strain of Trichoderma
atroviride mycovirus 1 (TaMV1-NFCF377). Electron
microscopy image exhibited an icosahedral viral particle of
40 nm diameter. Virus-cured isogenic isolates were generated
and no differences in growth rate, colony morphology, or
conidia production were observed between virus-infected and
virus-cured strains. However, culture filtrates of TaMV1-
NFCF377-infected strain showed enhanced antifungal activity
against the plant pathogen Rhizoctonia solani but not to
edible mushroom Pleurotus ostreatus. These results suggested
that TaMV1-NFCF377 affected the metabolism of the fungal
host to potentiate antifungal compounds against a plant pathogen,
but this enhanced antifungal activity appeared to be
species-specific.
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