Romano, I. G. | bioRxiv Science

bioRxiv2026

Temperature-Switchable Genome Editors from Extremophile-Derived Integrases

Integrases are site-specific recombinases encoded by phages and other mobile genetic elements. They mediate DNA integration, excision, and inversion between cognate attachment (att) sites. Although integrases are powerful tools for genetic engineering and synthetic biology, most systems lack intrinsic mechanisms that limit activity after expression, creating potential for unintended recombination. We hypothesized that extremophiles could provide temperature-responsive integrases because their enzymes evolved under selective pressure to operate within the thermal ranges experienced by their hosts. To test this concept, we linked integrase-att pairs from 458,683 prokaryotic genome assemblies to curated host growth-temperature metadata. This analysis revealed temperature-associated structure among integrase clusters and established a candidate pool for testing temperature-responsive recombinases. GC content in tyrosine integrase-associated attB sites showed a modest increase in higher-temperature hosts. We developed an inversion assay using a single-copy reporter plasmid and sacB counterselection to quantify integrase activity across temperatures. Thermophile derived integrases from Thermus thermophilus and Geobacillus stearothermophilus displayed hot-ON/cold-OFF activity profiles, whereas an integrase derived from the psychrotroph Pseudomonas cerasi showed cold-ON/hot-OFF activity. Together, these results establish host thermal niche as a guide for discovering intrinsically temperature switchable integrases and provide a foundation for engineering thermally controlled genome editing systems.

molecular biology↗

bioRxiv2024

A two-dose regimen of Qβ virus-like particle-based vaccines elicit protective antibodies against heroin and fentanyl

Opioid overdoses and the growing rate of opioid use disorder (OUD) are major public health concerns, particularly in the United States. Current treatment approaches for OUD have failed to slow the growth of the opioid crisis. Opioid vaccines have shown pre-clinical success in targeting multiple different opioid drugs. However, the need for many immunizations can limit their clinical implementation. In this study, we investigate the development of novel opioid vaccines by independently targeting fentanyl and the active metabolites of heroin using a bacteriophage virus-like particle (VLP) vaccine platform. We establish the successful conjugation of haptens to bacteriophage Q{beta} VLPs and demonstrate immunogenicity of Q{beta}-fentanyl, Q{beta}-morphine, and Q{beta}-6-acetylmorphine in animal models after one or two immunizations. We show that in independently or in combination, these vaccines elicit high-titer, high-avidity, and durable antibody responses. Moreover, we reveal their protective capacities against heroin or fentanyl challenge after two immunizations. Overall, these findings establish Q{beta}-VLP conjugated vaccines for heroin and fentanyl as very promising opioid vaccine candidates.

immunology↗