Introducing the UK Crop Microbiome Cryobank data resource, AgMicrobiomeBase, with case studies and methods on metabarcoding analyses.

Background: Here, we describe AgMicrobiomeBase as an output of the UK Crop Microbiome Cryobank (UKCMCB) project, including details of the underlying meta-barcode sequence-based methods and three microbiome analysis case studies. The UKCMCB links genomic datasets and associated soil metadata with a cryobank collection of samples, for six economically significant crops: fava bean (Vicia faba), oil seed rape (Brassica napus), spring barley (Hordeum vulgare), spring oats (Avena sativa), spring wheat (Triticum aestivum) and sugar beet (Beta vulgaris). The crops were grown in nine agricultural soils from the UK, representing three major soil texture classes.

A retropepsin-like bacterial protease regulates ribosome modification and polypeptide production.

Adaptations to fluctuating environmental conditions require bacteria to make large-scale proteomic shifts on short timescales. We previously characterised the tri-partite RimABK protein complex responsible for the post-translational modification of the ribosome in response to environmental cues. Regulated control of RpsF polyglutamylation by RimK rapidly influenced the proteome of Pseudomonas fluorescens cells to facilitate colonisation of the plant rhizosphere.

Correction: Plasmids manipulate bacterial behaviour through translational regulatory crosstalk.

[This corrects the article DOI: 10.1371/journal.pbio.

Compensatory mutations reducing the fitness cost of plasmid carriage occur in plant rhizosphere communities.

Plasmids drive bacterial evolutionary innovation by transferring ecologically important functions between lineages, but acquiring a plasmid often comes at a fitness cost to the host cell. Compensatory mutations, which ameliorate the cost of plasmid carriage, promote plasmid maintenance in simplified laboratory media across diverse plasmid-host associations. Whether such compensatory evolution can occur in more complex communities inhabiting natural environmental niches where evolutionary paths may be more constrained is, however, unclear.

Plasmids manipulate bacterial behaviour through translational regulatory crosstalk.

Beyond their role in horizontal gene transfer, conjugative plasmids commonly encode homologues of bacterial regulators. Known plasmid regulator homologues have highly targeted effects upon the transcription of specific bacterial traits. Here, we characterise a plasmid translational regulator, RsmQ, capable of taking global regulatory control in Pseudomonas fluorescens and causing a behavioural switch from motile to sessile lifestyle.

The UK Crop Microbiome Cryobank: a utility and model for supporting Phytobiomes research.

Plant microbiomes are the microbial communities essential to the functioning of the phytobiome-the system that consist of plants, their environment, and their associated communities of organisms. A healthy, functional phytobiome is critical to crop health, improved yields and quality food. However, crop microbiomes are relatively under-researched, and this is associated with a fundamental need to underpin phytobiome research through the provision of a supporting infrastructure.

Structural insights into the mechanism of adaptive ribosomal modification by Pseudomonas RimK.

Bacteria are equipped with a diverse set of regulatory tools that allow them to quickly adapt to their environment. The RimK system allows for Pseudomonas spp. to adapt through post-transcriptional regulation by altering the ribosomal subunit RpsF.

Pyocin S5 Import into Pseudomonas aeruginosa Reveals a Generic Mode of Bacteriocin Transport.

Pyocin S5 (PyoS5) is a potent protein bacteriocin that eradicates the human pathogen in animal infection models, but its import mechanism is poorly understood. Here, using crystallography, biophysical and biochemical analyses, and live-cell imaging, we define the entry process of PyoS5 and reveal links to the transport mechanisms of other bacteriocins. In addition to its C-terminal pore-forming domain, elongated PyoS5 comprises two novel tandemly repeated kinked 3-helix bundle domains that structure-based alignments identify as key import domains in other pyocins.