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Domain insertion engineering is a promising approach to recombine the functions of evolutionarily unrelated proteins. Insertion of light-switchable receptor domains into a selected effector protein, for instance, can yield allosteric effectors with light-dependent activity. However, the parameters that determine domain insertion tolerance and allostery are poorly understood. Here, an unbiased screen is used to systematically assess the domain insertion permissibility of several evolutionary unrelated proteins. Training machine learning models on the resulting data allow to dissect features informative for domain insertion tolerance and revealed sequence conservation statistics as the strongest indicators of suitable insertion sites. Finally, extending the experimental pipeline toward the identification of switchable hybrids results in opto-chemogenetic derivatives of the transcription factor AraC that function as single-protein Boolean logic gates. The study reveals determinants of domain insertion tolerance and yielded multimodally switchable proteins with unique functional properties.
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http://dx.doi.org/10.1002/advs.202303496 | DOI Listing |
Sci Adv
September 2025
Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
Integrins bind ligands between their alpha (α) and beta (β) subunits and transmit signals through conformational changes. Early in chordate evolution, some α subunits acquired an "inserted" (I) domain that expanded integrin's ligand-binding repertoire but obstructed the ancestral ligand pocket, seemingly blocking conventional integrin activation. Here, we compare cryo-electron microscopy structures of apo and ligand-bound states of the I domain-containing αEβ integrin and the I domain-lacking αβ integrin to illuminate how the I domain intrinsically mimics an extrinsic ligand to preserve integrin function.
View Article and Find Full Text PDFCell Rep
September 2025
Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; David Braley Center for Antibiotic Discovery, McMaster University, Hamilton, ON L8S 4K
Many Gram-negative bacteria use type VI secretion systems (T6SSs) to deliver toxic effector proteins into neighboring cells. Proteins in the VasX toxin family form ion-permeable channels in the bacterial cytoplasmic membrane that dissipate the proton motive force, thereby interfering with essential physiological processes. However, the structure of any VasX family effector has remained unknown.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139.
The mutagenic translesion synthesis (TLS) pathway, which is critically dependent on REV1's ability to recruit inserter TLS polymerases and the POLζ extender polymerase, enables cancer cells to bypass DNA lesions while introducing mutations that likely contribute to the development of chemotherapy resistance and secondary malignancies. Targeting this pathway represents a promising therapeutic strategy. Here, we demonstrate that the expression of the C-terminal domain (CTD) of human REV1, a ca.
View Article and Find Full Text PDFJ Appl Microbiol
September 2025
Laboratory of Food Microbiology and Hygiene, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashihiroshima 739-8528, Japan.
Aims: This study aims to investigate the genomic profile of a multidrug-resistant Escherichia coli strain, 160-11H1, co-carrying an extended-spectrum β-lactamase (ESBL) and the plasmid-mediated mobile colistin resistance gene, mcr-5.
Methods And Results: The entire genome of the strain was sequenced using Illumina MiSeq and Oxford Nanopore platforms, and de novo assembly was performed using Unicycler. The genome size was 5 031,330 bp and comprised 5 140 coding sequences.
Acta Crystallogr D Struct Biol
October 2025
Turkish Accelerator and Radiation Laboratory, 06830 Ankara, Türkiye.
Membrane-protein quality control in Escherichia coli involves coordinated actions of the AAA+ protease FtsH, the insertase YidC and the regulatory complex HflKC. These systems maintain proteostasis by facilitating membrane-protein insertion, folding and degradation. To gain structural insights into a putative complex formed by FtsH and YidC, we performed single-particle cryogenic electron microscopy on detergent-solubilized membrane samples, from which FtsH and YidC were purified using Ni-NTA affinity and size-exclusion chromatography.
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