DUF2285 is a novel helix-turn-helix domain variant that orchestrates both activation and antiactivation of conjugative element transfer in proteobacteria.

Horizontal gene transfer is tightly regulated in bacteria. Often only a fraction of cells become donors even when regulation of horizontal transfer is coordinated at the cell population level by quorum sensing. Here, we reveal the widespread 'domain of unknown function' DUF2285 represents an 'extended-turn' variant of the helix-turn-helix domain that participates in both transcriptional activation and antiactivation to initiate or inhibit horizontal gene transfer. Transfer of the integrative and conjugative element ICEMlSymR7A is controlled by the DUF2285-containing transcriptional activator FseA. One side of the DUF2285 domain of FseA has a positively charged surface which is required for DNA binding, while the opposite side makes critical interdomain contacts with the N-terminal FseA DUF6499 domain. The QseM protein is an antiactivator of FseA and is composed of a DUF2285 domain with a negative surface charge. While QseM lacks the DUF6499 domain, it can bind the FseA DUF6499 domain and prevent transcriptional activation by FseA. DUF2285-domain proteins are encoded on mobile elements throughout the proteobacteria, suggesting regulation of gene transfer by DUF2285 domains is a widespread phenomenon. These findings provide a striking example of how antagonistic domain paralogues have evolved to provide robust molecular control over the initiation of horizontal gene transfer

Extreme managers, extreme workplaces: capitalism, organizations and corporate psychopaths

This paper reports on in-depth, qualitative research carried out in England in 2013 among five organizational directors and two senior managers who had worked with other senior directors or managers who were Corporate Psychopaths, as measured by a management psychopathy measure. The Corporate Psychopaths reported on in this research displayed remarkable consistency in their approach to management to the extent that they could be called “text book examples” of managerial psychopathy. They were seen as being organizational stars and as deserving of performance awards by those above them, while the Corporate Psychopaths simultaneously subjected those below them to extreme forms of behavior, including bullying, intimidation and coercion and also engaged in extreme forms of mismanagement; such as very poor levels of personnel management, directionless leadership, miss-management of resources and outright fraud

The NifA-RpoN regulon of Mesorhizobium loti strain R7A and its symbiotic activation by a novel LacI/GalR-family regulator.

Mesorhizobium loti is the microsymbiont of Lotus species, including the model legume L. japonicus. M. loti differs from other rhizobia in that it contains two copies of the key nitrogen fixation regulatory gene nifA, nifA1 and nifA2, both of which are located on the symbiosis island ICEMlSym(R7A). M. loti R7A also contains two rpoN genes, rpoN1 located on the chromosome outside of ICEMlSym(R7A) and rpoN2 that is located on ICEMlSym(R7A). The aims of the current work were to establish how nifA expression was activated in M. loti and to characterise the NifA-RpoN regulon. The nifA2 and rpoN2 genes were essential for nitrogen fixation whereas nifA1 and rpoN1 were dispensable. Expression of nifA2 was activated, possibly in response to an inositol derivative, by a novel regulator of the LacI/GalR family encoded by the fixV gene located upstream of nifA2. Other than the well-characterized nif/fix genes, most NifA2-regulated genes were not required for nitrogen fixation although they were strongly expressed in nodules. The NifA-regulated nifZ and fixU genes, along with nifQ which was not NifA-regulated, were required in M. loti for a fully effective symbiosis although they are not present in some other rhizobia. The NifA-regulated gene msi158 that encodes a porin was also required for a fully effective symbiosis. Several metabolic genes that lacked NifA-regulated promoters were strongly expressed in nodules in a NifA2-dependent manner but again mutants did not have an overt symbiotic phenotype. In summary, many genes encoded on ICEMlSym(R7A) were strongly expressed in nodules but not free-living rhizobia, but were not essential for symbiotic nitrogen fixation. It seems likely that some of these genes have functional homologues elsewhere in the genome and that bacteroid metabolism may be sufficiently plastic to adapt to loss of certain enzymatic functions

Symbiosis islands of Loteae-nodulating Mesorhizobium comprise three radiating lineages with concordant nod gene complements and nodulation host-range groupings.

© 2020 The Authors Mesorhizobium is a genus of soil bacteria, some isolates of which form an endosymbiotic relationship with diverse legumes of the Loteae tribe. The symbiotic genes of these mesorhizobia are generally carried on integrative and conjugative elements termed symbiosis islands (ICESyms). Mesorhizobium strains that nodulate Lotus spp. have been divided into host-range groupings. Group I (GI) strains nodulate L. corniculatus and L. japonicus ecotype Gifu, while group II (GII) strains have a broader host range, which includes L. pedunculatus. To identify the basis of this extended host range, and better understand Mesorhizobium and ICESym genomics, the genomes of eight Mesorhizobium strains were completed using hybrid long- and short-read assembly. Bioinformatic comparison with previously sequenced mesorhizobia genomes indicated host range was not predicted by Mesorhizobium genospecies but rather by the evolutionary relationship between ICESym symbiotic regions. Three radiating lineages of Loteae ICESyms were identified on this basis, which correlate with Lotus spp. host-range grouping and have lineage-specific nod gene complements. Pangenomic analysis of the completed GI and GII ICESyms identified 155 core genes (on average 30.1 % of a given ICESym). Individual GI or GII ICESyms carried diverse accessory genes with an average of 34.6 % of genes unique to a given ICESym. Identification and comparative analysis of NodD symbiotic regulatory motifs - nod boxes - identified 21 branches across the NodD regulons. Four of these branches were associated with seven genes unique to the five GII ICESyms. The nod boxes preceding the host-range gene nodZ in GI and GII ICESyms were disparate, suggesting regulation of nodZ may differ between GI and GII ICESyms. The broad host-range determinant(s) of GII ICESyms that confer nodulation of L. pedunculatus are likely present amongst the 53 GII-unique genes identified

<i>M. loti</i> mutants constructed in this study and their symbiotic phenotypes.

a<p>IDM  =  insertion duplication mutant in which coding sequence disrupted; CMD  =  <i>cis</i>-merodiploid insertion mutant in which gene is not inactivated as mutant retains wild-type copy of gene including entire promoter region downstream of <i>lacZ</i> fusion (except for JS16 and JS17 in which promoter is truncated).</p>b<p>Symbiotic effectiveness of mutants determined by measuring the wet weights of 15 <i>L. corniculatus</i> seedlings at 6 weeks post-inoculation. Data were compared with those obtained for seedlings inoculated with the wild-type and uninoculated controls. +  =  Fix⁺ (fully effective); −  =  Fix⁻ (ineffective); P  =  partially effective (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053762#pone-0053762-t005" target="_blank">Table 5</a>).</p

Potential NifA-regulated operons on ICE<i>Ml</i>Sym^R7A.

<p>Potential NifA-regulated operons on ICE<i>Ml</i>Sym^R7A.</p

<i>The fixV-nifA2</i> region.

<p>A. Map of the <i>fixV-nifA2</i> region. The location of gene fragments in the intergenic region with homology at the protein level to Msi109 is shown. The inserts in the plasmids pJS104 and pJS100 used for complementation of <i>fixV</i> and <i>nifA2</i> mutants respectively are indicated above the map. Below the map are the intergenic fragments used to locate the <i>nifA2</i> promoter. The sizes of the intergenic fragments are shown on the left and the Fix phenotype of the resultant strains on the right. B. BlastN output showing nucleotide identity between the <i>fixV-nifA2</i> intergenic region and the <i>msi109</i> region. The ATG corresponding to the start codon of <i>msi109</i> is bolded and underlined. C. BlastX output showing amino-acid similarity between the two fragments in the <i>fixV-nifA2</i> intergenic region and Msi109.</p