Variable orthogonality of RDF - large serine integrase interactions within the ϕC31 family.

Large serine integrases are phage- (or mobile element-) encoded enzymes that catalyse site-specific recombination reactions between a short DNA sequence on the phage genome (attP) and a corresponding host genome sequence (attB), thereby integrating the phage DNA into the host genome. Each integrase has its unique pair of attP and attB sites, a feature that allows them to be used as orthogonal tools for genome modification applications. In the presence of a second protein, the Recombination Directionality Factor (RDF), integrase catalyses the reverse, excisive reaction, generating new recombination sites, attR and attL. In addition to promoting attR x attL reaction, the RDF inhibits attP x attB recombination. This feature makes the directionality of integrase reactions programmable, allowing them to be useful for building synthetic biology devices. In this report, we describe the degree of orthogonality of both integrative and excisive reactions for three related integrases (ϕC31, ϕBT1, and TG1) and their RDFs. Among these, TG1 integrase is the most active, showing near complete recombination in both attP x attB and attR x attL reactions, and the most directional in the presence of its RDF. Our findings show that there is varying orthogonality among these three integrases - RDF pairs: ϕC31 integrase was the least selective, with all three RDFs activating it for attR x attL recombination. Similarly, ϕC31 RDF was the least effective among the three RDFs in promoting the excisive activities of the integrases, including its cognate ϕC31 integrase. ϕBT1 and TG1 RDFs were noticeably more effective than ϕC31 RDF at inhibiting attP x attB recombination by their respective integrases, making them more suitable for building reversible genetic switches. AlphaFold-Multimer predicts very similar structural interactions between each cognate integrase - RDF pair. The binding surface on RDF is much more conserved than the binding surface on integrase, an indication that specificity is determined more by the integrase than the RDF. Overall, the observed weak integrase/RDF orthogonality across the three enzymes emphasizes the need for identifying and characterizing more integrase - RDF pairs. Additionally, the ability of a particular integrase's preferred reaction direction to be controlled to varying degrees by non-cognate RDFs provides a path to tunable, non-binary genetic switches.

Environmental Screening of Electrode Materials for a Rechargeable Aluminum Battery with an AlCl3/EMIMCl Electrolyte.

Recently, rechargeable aluminum batteries have received much attention due to their low cost, easy operation, and high safety. As the research into rechargeable aluminum batteries with a room-temperature ionic liquid electrolyte is relatively new, research efforts have focused on finding suitable electrode materials. An understanding of the environmental aspects of electrode materials is essential to make informed and conscious decisions in aluminum battery development. The purpose of this study was to evaluate and compare the relative environmental performance of electrode material candidates for rechargeable aluminum batteries with an AlCl3/EMIMCl (1-ethyl-3-methylimidazolium chloride) room-temperature ionic liquid electrolyte. To this end, we used a lifecycle environmental screening framework to evaluate 12 candidate electrode materials. We found that all of the studied materials are associated with one or more drawbacks and therefore do not represent a "silver bullet" for the aluminum battery. Even so, some materials appeared more promising than others did. We also found that aluminum battery technology is likely to face some of the same environmental challenges as Li-ion technology but also offers an opportunity to avoid others. The insights provided here can aid aluminum battery development in an environmentally sustainable direction.

Acute extracellular matrix, inflammatory and MAPK response to lengthening contractions in elderly human skeletal muscle.

To uncover potential factors that may be involved in the impaired regenerative capacity of aged skeletal muscle, we comprehensively assessed the molecular stress response following muscle damage in old and young individuals. 10 young (22.7 ±â€¯2.25 yrs) and 8 physically active old (70.9 ±â€¯7.5 yrs) subjects completed a bout of 300 lengthening contractions (LC), and muscle biopsies were taken pre-exercise and at 3, 24, and 72 h post-LC. Both age groups performed the same amount of work during LC, with the old group displaying a resistance to LC-induced fatigue during the exercise. Muscle damage was evident by soreness and losses in isokinetic force and power production, though older subjects experienced reduced force and power losses relative to the young group. The acute extracellular matrix (ECM) response was characterized by substantial increases in the glycoproteins tenascin C and fibronectin in the young, which were blunted in the old muscle following damage. Old muscle displayed a generally heightened and asynchronous inflammatory response compared to young muscle, with higher expression of MCP-1 that appeared at later time points, and increased NF-κb activity. Expression of the stress-related MAPKs P38 and JNK increased only in the old groups following muscle damage. In summary, aberrations appear in the inflammatory, ECM and MAPK responses of aged skeletal muscle following damaging LC, each of which may individually or collectively contribute to the deterioration of muscle repair mechanisms that accompanies aging.