Identification and characterization of a direct activator of a gene transfer agent

Gene transfer agents (GTAs) are thought to be ancient bacteriophages that have been co-opted into serving their host and can now transfer any gene between bacteria. Production of GTAs is controlled by several global regulators through unclear mechanisms. In Rhodobacter capsulatus, gene rcc01865 encodes a putative regulatory protein that is essential for GTA production. Here, I show that rcc01865 (hereafter gafA) encodes a transcriptional regulator that binds to the GTA promoter to initiate production of structural and DNA packaging components. Expression of gafA is in turn controlled by the pleiotropic regulator protein CtrA and the quorum-sensing regulator GtaR. GafA and CtrA work together to promote GTA maturation and eventual release through cell lysis. Identification of GafA as a direct GTA regulator allows the first integrated regulatory model to be proposed and paves the way for discovery of GTAs in other species that possess gafA homologues

Absorptive capacity and innovation: When is it better to cooperate?

Cooperation can benefit and hurt firms at the same time. An important question then is: when is it better to cooperate? And, once the decision to cooperate is made, how can an appropriate partner be selected? In this paper we present a model of inter-firm cooperation driven by cognitive distance, appropriability conditions and external knowledge. Absorptive capacity of firms develops as an outcome of the interaction between absorptive R&D and cognitive distance from voluntary and involuntary knowledge spillovers. Thus, we offer a revision of the original model by Cohen and Levinthal (Econ J 99(397):569-596, 1989), accounting for recent empirical findings and explicitly modeling absorptive capacity within the framework of interactive learning. We apply that to the analysis of firms' cooperation and R&D investment preferences. The results show that cognitive distance and appropriability conditions between a firm and its cooperation partner have an ambiguous effect on the profit generated by the firm. Thus, a firm chooses to cooperate and selects a partner conditional on the investments in absorptive capacity it is willing to make to solve the understandability/novelty trade-off. © 2014 Springer-Verlag Berlin Heidelberg

Cross-talk towards the response regulator NtrC controlling nitrogen metabolism in Rhodobacter capsulatus

Rhodobacter capsulatus NtrB/NtrC two-component regulatory system controls expression of genes involved in nitrogen metabolism including urease and nitrogen fixation genes. The ntrY-ntrX genes, which are located immediately downstream of the nifR3-ntrB-ntrC operon, code for a two-component system of unknown function. Transcription of ntrY starts within the ntrC-ntrY intergenic region as shown by primer extension analysis, but maximal transcription requires, in addition, the promoter of the nifR3-ntrB-ntrC operon. While ntrB and ntrY single mutant strains were able to grow with either urea or N-2 as sole nitrogen source, a ntrB/ntrY double mutant (like a ntrC-deficient strain) was no longer able to use urea or N-2. These findings suggest that the histidine kinases NtrB and NtrY can substitute for each other as phosphodonors towards the response regulator NtrC