Stepwise evolution of the Sec machinery in Proteobacteria

The Sec machinery facilitates the translocation of proteins across and into biological membranes. In several of the Proteobacteria, this machinery contains accessory features that are not present in any other bacterial division. The genomic distribution of these features in the context of bacterial phylogeny suggests that the Sec machinery has evolved in discrete steps. The canonical Sec machinery was initially supplemented with SecB; subsequently, SecE was extended with two transmembrane segments and, finally, SecM was introduced. The Sec machinery of Escherichia coli and other Enterobacteriales represents the end product of this stepwise evolution.</p

FE calculations on a three stage metal forming process of Sandvik Nanoflex

Sandvik NanoflexTM combines good corrosion resistance with high strength. This steel has good deformability in\ud austenitic conditions. It belongs to the group of metastable austenites, which means that during deformation a strain-induced\ud transformation into martensite takes place. After deformation, transformation continues as a result of internal stresses. Both\ud transformations are stress-state and temperature dependent. A constitutive model for this steel has been formulated, based\ud on the macroscopic material behaviour measured by inductive measurements. Both the stress-assisted and the strain-induced\ud transformation into martensite have been incorporated in this model. Path-dependent work hardening has also been taken\ud into account. This article describes how the model is implemented in an internal Philips FE code called CRYSTAL, which is\ud a dedicated robust and accurate finite element solver. The implementation is based on lookup tables in combination with\ud feed-forward neural networks. The radial return method is used to determine the material state during and after plastic\ud flow, however, it has been extended to cope with the stiff character of the partial differential equation that describes the\ud transformation behaviour

Evolution of YidC/Oxa1/Alb3 insertases: three independent gene duplications followed by functional specialization in bacteria, mitochondria and chloroplasts

Members of the YidC/Oxa1/Alb3 protein family facilitate the insertion, folding and assembly of proteins of the inner membranes of bacteria and mitochondria and the thylakoid membrane of plastids. All homologs share a conserved hydrophobic core region comprising five transmembrane domains. On the basis of phylogenetic analyses, six subgroups of the family can be distinguished which presumably arose from three independent gene duplications followed by functional specialization. During evolution of bacteria, mitochondria and chloroplasts, subgroup-specific regions were added to the core domain to facilitate the association with ribosomes or other components contributing to the substrate spectrum of YidC/Oxa1/Alb3 proteins

A designer FG-Nup that reconstitutes the selective transport barrier of the nuclear pore complex

Nuclear Pore Complexes (NPCs) regulate bidirectional transport between the nucleus and the cytoplasm. Intrinsically disordered FG-Nups line the NPC lumen and form a selective barrier, where transport of most proteins is inhibited whereas specific transporter proteins freely pass. The mechanism underlying selective transport through the NPC is still debated. Here, we reconstitute the selective behaviour of the NPC bottom-up by introducing a rationally designed artificial FG-Nup that mimics natural Nups. Using QCM-D, we measure selective binding of the artificial FG-Nup brushes to the transport receptor Kap95 over cytosolic proteins such as BSA. Solid-state nanopores with the artificial FG-Nups lining their inner walls support fast translocation of Kap95 while blocking BSA, thus demonstrating selectivity. Coarse-grained molecular dynamics simulations highlight the formation of a selective meshwork with densities comparable to native NPCs. Our findings show that simple design rules can recapitulate the selective behaviour of native FG-Nups and demonstrate that no specific spacer sequence nor a spatial segregation of different FG-motif types are needed to create selective NPCs