Thermoplastic elastomer hydrogels via self-assembly of an elastin-mimetic triblock polypeptide

Protein-based analogues of conventional thermoplastic elastomers can be designed with enhanced properties as a consequence of the precise control of primary structure. Protein 1 undergoes a reversible sol-gel transition, which results in the formation of a well-defined elastomeric network above a lower critical solution temperature. The morphology of the network is consistent with selective microscopic phase separation of the endblock domains. This genetic engineering approach provides a method for specification of the critical architectural parameters. such as block length and sequence, which define macromolecular properties that are important for downstream applications

Archaeal DNA-import apparatus is homologous to bacterial conjugation machinery

Conjugation is a major mechanism of horizontal gene transfer promoting the spread of antibiotic resistance among human pathogens. It involves establishing a junction between a donor and a recipient cell via an extracellular appendage known as the mating pilus. In bacteria, the conjugation machinery is encoded by plasmids or transposons and typically mediates the transfer of cognate mobile genetic elements. Much less is known about conjugation in archaea. Here, we determine atomic structures by cryo-electron microscopy of three conjugative pili, two fromhyperthermophilic archaea (Aeropyrum pernix and Pyrobaculum calidifontis) and one encoded by the Ti plasmid of the bacterium Agrobacterium tumefaciens, and show that the archaeal pili are homologous to bacterial mating pili. However, the archaeal conjugation machinery, known as Ced, has been ‘domesticated’, that is, the genes for the conjugation machinery are encoded on the chromosome rather than on mobile genetic elements, and mediates the transfer of cellular DNA.</p