scholarly journals LuxS-dependent AI-2 production is not involved in global regulation of natural product biosynthesis inPhotorhabdusandXenorhabdus

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3471 ◽  
Author(s):  
Antje K. Heinrich ◽  
Merle Hirschmann ◽  
Nick Neubacher ◽  
Helge B. Bode
Keyword(s):  
Regulatory System ◽  
Regulatory Rna ◽  
Insect Larvae ◽  
Phenotypic Differences ◽  
Global Regulators ◽  
Autoinducer 2 ◽  
Small Regulatory Rna ◽  
Mutant Strains ◽  
Different Strains

The Gram-negative bacteriaPhotorhabdusandXenorhabdusare known to produce a variety of different natural products (NP). These compounds play different roles since the bacteria live in symbiosis with nematodes and are pathogenic to insect larvae in the soil. Thus, a fine tuned regulatory system controlling NP biosynthesis is indispensable. Global regulators such as Hfq, Lrp, LeuO and HexA have been shown to influence NP production ofPhotorhabdusandXenorhabdus. Additionally, photopyrones as quorum sensing (QS) signals were demonstrated to be involved in the regulation of NP production inPhotorhabdus.In this study, we investigated the role of another possible QS signal, autoinducer-2 (AI-2), in regulation of NP production. The AI-2 synthase (LuxS) is widely distributed within the bacterial kingdom and has a dual role as a part of the activated methyl cycle pathway, as well as being responsible for AI-2 precursor production. We deletedluxSin three different entomopathogenic bacteria and compared NP levels in the mutant strains to the wild type (WT) but observed no difference to the WT strains. Furthermore, the absence of the small regulatory RNAmicA, which is encoded directly upstream ofluxS, did not influence NP levels. Phenotypic differences between theP. luminescens luxSdeletion mutant and an earlier describedluxSdeficient strain ofP. luminescenssuggested that two phenotypically different strains have evolved in different laboratories.

scholarly journals Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni

2021 ◽  
Author(s):  
Martin Tereň ◽  
Ekaterina Shagieva ◽  
Lucie Vondrakova ◽  
Jitka Viktorova ◽  
Viviana Svarcova ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Biofilm Formation ◽  
Early Stage ◽  
Wild Type ◽  
Genetic Determinants ◽  
Autoinducer 2 ◽  
Naturally Occurring ◽  
Mutant Strains ◽  
The Impact

Abstract Currently, it is clear that the luxS gene has an impact on the process of biofilm formation in Campylobacter jejuni. However, even within the species naturally occurring strains of Campylobacter lacking the luxS gene exist, which can form biofilms. In order to better understand the genetic determinants and the role of quorum sensing through the LuxS/AI-2 pathway in biofilm formation, a set of mutant/complemented strains of C. jejuni 81–176 were prepared. Additionally, the impact of the mutagenic strategy used against the luxS gene was investigated. Biofilm formation was affected by both the presence and absence of the luxS gene, and by the mutagenic strategy used. Analysis by CLSM showed that all mutant strains formed significantly less biofilm mass when compared to the wild-type. Interestingly, the deletion mutant (∆luxS) showed a larger decrease in biofilm mass than the substitution (∙luxS) and insertional inactivated (⸬luxS) mutants, even though all the mutant strains lost the ability to produce autoinducer-2 molecules. Moreover, the biofilm of the ∆luxS mutant lacked the characteristic microcolonies observed in all other strains. The complementation of all mutant strains resulted in restored ability to produce AI-2, to form a complex biofilm, and to develop microcolonies at the level of the wild-type.

scholarly journals Regulation of the Chlamydia trachomatis Histone H1-Like Protein Hc2 Is IspE Dependent and IhtA Independent

2006 ◽  
Vol 188 (14) ◽  
pp. 5289-5292 ◽  
Author(s):  
Nicole A. Grieshaber ◽  
Janet Burgess Sager ◽  
Cheryl A. Dooley ◽  
Stanley F. Hayes ◽  
Ted Hackstadt
Keyword(s):  
Gene Expression ◽  
Chlamydia Trachomatis ◽  
Chromatin Structure ◽  
Histone H1 ◽  
Regulatory Rna ◽  
Developmentally Regulated ◽  
Global Regulators ◽  
Small Regulatory Rna ◽  
Expression And Activity

ABSTRACT The chlamydial histone-like proteins, Hc1 and Hc2, function as global regulators of chromatin structure and gene expression. Hc1 and Hc2 expression and activity are developmentally regulated. A small metabolite that disrupts Hc1 interaction with DNA also disrupts Hc2 interactions; however, the small regulatory RNA that inhibits Hc1 translation is specific to Hc1.

scholarly journals Identification of CsrC and Characterization of Its Role in Epithelial Cell Invasion in Salmonella enterica Serovar Typhimurium

2006 ◽  
Vol 74 (1) ◽  
pp. 331-339 ◽  
Author(s):  
Doreen R. Fortune ◽  
Mitsu Suyemoto ◽  
Craig Altier
Keyword(s):  
Cell Invasion ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Regulatory Rna ◽  
Two Component ◽  
Serovar Typhimurium ◽  
Regulatory Rnas ◽  
The Stability

ABSTRACT The csr regulatory system of Salmonella regulates the expression of the genes of Salmonella pathogenicity island 1 (SPI1) required for the invasion of epithelial cells. This system consists of the posttranscriptional regulator CsrA and an untranslated regulatory RNA, CsrB, that opposes the action of CsrA. Here we identify and characterize the role of a second regulatory RNA, CsrC, whose ortholog was discovered previously in Escherichia coli. We show that a mutant of csrC has only mild defects in invasion and the expression of SPI1 genes, as does a mutant of csrB, but that a double csrB csrC mutant is markedly deficient in these properties, suggesting that the two regulatory RNAs play redundant roles in the control of invasion. We further show that CsrC, like CsrB, is controlled by the BarA/SirA two-component regulator but that a csrB csrC mutant exhibits a loss of invasion equivalent to that of a barA or sirA mutant, indicating that much of the effect of BarA/SirA on invasion functions through its control of CsrB and CsrC. In addition to their control by BarA/SirA, each regulatory RNA is also controlled by other components of the csr system. The loss of csrB was found to increase the level of CsrC by sevenfold, while the loss of csrC increased CsrB by nearly twofold. Similarly, the overexpression of csrA increased CsrC by nearly 11-fold and CsrB by 3-fold and also significantly increased the stability of both RNAs.

Small Regulatory Molecules Acting Big in Cancer: Potential Role of Mito-miRs in Cancer

2019 ◽  
Vol 19 (9) ◽  
pp. 621-631 ◽  
Author(s):  
Praveen Sharma ◽  
Bharat ◽  
Nilambra Dogra ◽  
Sandeep Singh
Keyword(s):  
Gene Expression ◽  
Mitochondrial Genome ◽  
Potential Role ◽  
Regulatory Rna ◽  
Rna Molecules ◽  
Small Regulatory Rna ◽  
Physiological Processes ◽  
Current Review ◽  
Posttranscriptional Level

MicroRNAs [miRNAs] are short, non-coding, single stranded RNA molecules regulating gene expression of their targets at the posttranscriptional level by either degrading mRNA or by inhibiting translation. Previously, miRNAs have been reported to be present inside the mitochondria and these miRNAs have been termed as mito-miRs. Origin of these mito-miRs may either be from mitochondrial genome or import from nucleus. The second class of mito-miRs makes it important to unravel the involvement of miRNAs in crosstalk between nucleus and mitochondria. Since miRNAs are involved in various physiological processes, their deregulation is often associated with disease progression, including cancer. The current review focuses on the involvement of miRNAs in different mitochondrial mediated processes. It also highlights the importance of exploring the interaction of miRNAs with mitochondrial genome, which may lead to the development of small regulatory RNA based therapeutic options.

scholarly journals Regulation of ompA mRNA stability: the role of a small regulatory RNA in growth phase-dependent control

2005 ◽  
Vol 58 (5) ◽  
pp. 1421-1429 ◽  
Author(s):  
Anders Aamann Rasmussen ◽  
Maiken Eriksen ◽  
Kambiz Gilany ◽  
Christina Udesen ◽  
Thomas Franch ◽  
...  
Keyword(s):  
Growth Phase ◽  
Mrna Stability ◽  
Regulatory Rna ◽  
Small Regulatory Rna

THYROID STIMULATORS AND THYROID STIMULATION

1971 ◽  
Vol 66 (3) ◽  
pp. 558-576 ◽  
Author(s):  
Gerald Burke
Keyword(s):  
Regulatory System ◽  
Control Site ◽  
Thyroid Cell ◽  
Primary Control ◽  
Physico Chemical ◽  
Site Of Action ◽  
Long Acting

ABSTRACT A long-acting thyroid stimulator (LATS), distinct from pituitary thyrotrophin (TSH), is found in the serum of some patients with Graves' disease. Despite the marked physico-chemical and immunologic differences between the two stimulators, both in vivo and in vitro studies indicate that LATS and TSH act on the same thyroidal site(s) and that such stimulation does not require penetration of the thyroid cell. Although resorption of colloid and secretion of thyroid hormone are early responses to both TSH and LATS, available evidence reveals no basic metabolic pathway which must be activated by these hormones in order for iodination reactions to occur. Cyclic 3′, 5′-AMP appears to mediate TSH and LATS effects on iodination reactions but the role of this compound in activating thyroidal intermediary metabolism is less clear. Based on the evidence reviewed herein, it is suggested that the primary site of action of thyroid stimulators is at the cell membrane and that beyond the(se) primary control site(s), there exists a multifaceted regulatory system for thyroid hormonogenesis and cell growth.

Monitoring the marine environment for small round structured viruses (SRSVS): a new approach to combating the transmission of these viruses by molluscan shellfish

1998 ◽  
Vol 38 (12) ◽  
pp. 51-56 ◽  
Author(s):  
K. Henshilwood ◽  
J. Green ◽  
D. N. Lees
Keyword(s):  
Enteric Virus ◽  
Winter Period ◽  
Rt Pcr ◽  
Cloning And Sequencing ◽  
New Approach ◽  
Human Enteric Virus ◽  
Different Strains ◽  
The Uk ◽  
Public Health Protection

This study investigates human enteric virus contamination of a shellfish harvesting area. Samples were analysed over a 14-month period for Small Round Structured Viruses (SRSVs) using a previously developed nested RT-PCR. A clear seasonal difference was observed with the largest numbers of positive samples obtained during the winter period (October to March). This data concurs with the known winter association of gastroenteric illness due to oyster consumption in the UK and also with the majority of the outbreaks associated with shellfish harvested from this area during the study period. RT-PCR positive amplicons were further characterised by cloning and sequencing. Sequence analysis of the positive samples identified eleven SRSV strains, of both Genogroup I and Genogroup II, occurring throughout the study period. Many shellfish samples contained a mixture of strains with a few samples containing up to three different strains with both Genogroups represented. The observed common occurrence of strain mixtures may have implications for the role of shellfish as a vector for dissemination of SRSV strains. These results show that nested RT-PCR can identify SRSV contamination in shellfish harvesting areas. Virus monitoring of shellfish harvesting areas by specialist laboratories using RT-PCR is a possible approach to combating the transmission of SRSVs by molluscan shellfish and could potentially offer significantly enhanced levels of public health protection.

scholarly journals RND Efflux Systems Contribute to Resistance and Virulence of Aliarcobacter butzleri

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 823
Author(s):  
Cristiana Mateus ◽  
Ana Rita Nunes ◽  
Mónica Oleastro ◽  
Fernanda Domingues ◽  
Susana Ferreira
Keyword(s):  
Oxidative Stress ◽  
Human Serum ◽  
Ethidium Bromide ◽  
Biofilm Formation ◽  
Bacterial Resistance ◽  
Efflux Pumps ◽  
Bacterial Virulence ◽  
Relative Fitness ◽  
Mutant Strains

Aliarcobacter butzleri is an emergent enteropathogen that can be found in a range of environments. This bacterium presents a vast repertoire of efflux pumps, such as the ones belonging to the resistance nodulation cell division family, which may be associated with bacterial resistance, as well as virulence. Thus, this work aimed to evaluate the contribution of three RND efflux systems, AreABC, AreDEF and AreGHI, in the resistance and virulence of A. butzleri. Mutant strains were constructed by inactivation of the gene that encodes the inner membrane protein of these systems. The bacterial resistance profile of parental and mutant strains to several antimicrobials was assessed, as was the intracellular accumulation of the ethidium bromide dye. Regarding bacterial virulence, the role of these three efflux pumps on growth, strain fitness, motility, biofilm formation ability, survival in adverse conditions (oxidative stress and bile salts) and human serum and in vitro adhesion and invasion to Caco-2 cells was evaluated. We observed that the mutants from the three efflux pumps were more susceptible to several classes of antimicrobials than the parental strain and presented an increase in the accumulation of ethidium bromide, indicating a potential role of the efflux pumps in the extrusion of antimicrobials. The mutant strains had no bacterial growth defects; nonetheless, they presented a reduction in relative fitness. For the three mutants, an increase in the susceptibility to oxidative stress was observed, while only the mutant for AreGHI efflux pump showed a relevant role in bile stress survival. All the mutant strains showed an impairment in biofilm formation ability, were more susceptible to human serum and were less adherent to intestinal epithelial cells. Overall, the results support the contribution of the efflux pumps AreABC, AreDEF and AreGHI of A. butzleri to antimicrobial resistance, as well as to bacterial virulence.

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