Folate status of gut microbiome affects Caenorhabditis elegans lifespan

In a paper in BMC Biology Virk et al. show that Caenorhabditis elegans lifespan is extended in response to a diet of folate-deficient Escherichia coli.
The deficiencies in folate biosynthesis were due to an aroD mutation, or treatment of E. coli with sulfa drugs, which are mimics of the folate precursor para-aminobenzoic acid. This study suggests that pharmacological manipulation of the gut microbiome folate status may be a viable approach to slow animal aging, and raises questions about folate supplementation.

Original Source:

A New Zebrafish Model of Oro-Intestinal Pathogen Colonization Reveals a Key Role for Adhesion in Protection by Probiotic Bacteria

The beneficial contribution of commensal bacteria to host health and homeostasis led to the concept that exogenous non-pathogenic bacteria called probiotics could be used to limit disease caused by pathogens. However, despite recent progress using gnotobiotic mammal and invertebrate models, mechanisms underlying protection afforded by commensal and probiotic bacteria against pathogens remain poorly understood. In this study authors have developed a zebrafish model of controlled co-infection in which germ-free zebrafish raised on axenic living protozoa enabled the study of interactions between host and commensal and pathogenic bacteria. Researchers have screened enteric fish pathogens and identified Edwardsiella ictaluri as a virulent strain inducing a strong inflammatory response and rapid mortality in zebrafish larvae infected by the natural oro-intestinal route. Using mortality induced by infection as a phenotypic read-out, researchers pre-colonized zebrafish larvae with 37 potential probiotic bacterial strains and screened for survival upon E. ictaluri infection. Researchers identified 3 robustly protective strains, including Vibrio parahaemolyticus and 2 Escherichia coli strains. Researchers showed that the observed protective effect of E. coli was not correlated with a reduced host inflammatory response, nor with the release of biocidal molecules by protective bacteria, but rather with the presence of specific adhesion factors such as F pili that promote the emergence of probiotic bacteria in zebrafish larvae. This study therefore provides new insights into the molecular events underlying the probiotic effect and constitutes a potentially high-throughput in vivo approach to the study of the molecular basis of pathogen exclusion in a relevant model of vertebrate oro-intestinal infection.

Original Source:

Effective expression of human proteins on bacterial magnetic particlesin an anchor gene deletion mutant of Magnetospirillum magneticum AMB-1

Biologically synthesized magnetic particles by magnetotactic bacteria (BacMPs) have promising potential in the area of functional protein display technology for various biotechnological and biomedical applications. Functional proteins fused with an anchor protein, Mms13, have been demonstrated to be an effective and stable method for the display of functional proteins on BacMPs. However, the expression of some human proteins is relatively low. Useful host strains of Escherichia coli have been developed for the enhanced expression of recombinant proteins using a genetic engineering approach. To improve human protein expression level on BacMPs in Magnetospirillum magneticum AMB-1, a mutant strain with a deleted native mms13 gene (Δmms13 strain) was established and evaluated for effective functional protein display technology. As a result, the Δmms13 strain synthesized BacMPs with significantly improved expression of two human proteins, thyroid-stimulating hormone receptor (TSHRaa1-165) and the class II major histocompatibility complex (MHC II) molecules. The Δmms13 strain could therefore be an effective strain for the display of other important human proteins on BacMPs and may be useful for further applications.

Original Source:

Investigating the prevalence of queuine in Escherichia coli RNA viaincorporation of the tritium-labeled precursor, preQ1

There are over 100 modified bases that occur in RNA with the majority found in transfer RNA. It has been widely believed that the queuine modification is limited to four transfer RNA species in vivo. However, given the vast amount of the human genome (60–70%) that is transcribed into non-coding RNA (Mattick [10]), probing the presence of modified bases in these RNAs is of fundamental importance. The mechanism of incorporation of queuine, via transglycosylation, makes this uniquely poised to probe base modification in RNA. Results of incubations of Escherichia coli cell cultures with [3H] preQ1 (a queuine precursor in eubacteria) clearly demonstrate preQ1 incorporation into a number of RNA species of various sizes larger than transfer RNA. Specifically, significant levels of preQ1 incorporation into ribosomal RNA are observed. The modification of other large RNAs was also observed. These results confirm that non-coding RNAs contain modified bases and lead to the supposition that these modifications are necessary to control non-coding RNA structure and function as has been shown for transfer RNA.

Original Source:

Novel iron-regulated and Fur-regulated small regulatory RNAs in Aggregatibacter actinomycetemcomitans

Iron can regulate biofilm formation via non-coding small RNA (sRNA). To determine if iron-regulated sRNAs are involved in biofilm formation by the periodontopathogen Aggregatibacter actinomycetemcomitans, total RNA was isolated from bacteria cultured with iron supplementation or chelation.