A drive for anti-counterfeiting technology has attracted considerable interests in developing nanomaterials with a wide range of colors and tunable optical properties in solid state. Herein, with a series of conjugated polymers and based on the host−guest driven self-assembly strategy, a color-tunable supramolecular nanoparticle-based system is reported, in which full-color as well as white fluorescence can be achieved. Moreover, this fluorescent platform exhibits reversible photoswitching between quenching and emission by noncovalently introducing a photoresponsive energy acceptor. In addition, an efficient chemiluminescence system with high intensity can also be obtained in a similar manner by introducing a H 2 O 2 -responsive energy donor. Significantly, chemiluminescence is advantageous over fluorescence since there is no need for external light irradiation. More importantly, these acceptor/donor-loaded supramolecular nanoparticles exhibit fluorescence/chemiluminescence modulation ability in both solution and solid state. Therefore, this supramolecular system can be employed as fluorescent security inks for anti-counterfeiting strategies and provide a proof-of-principle application.

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The accessory protein Orf6 is uniquely expressed in sarbecoviruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which is an ongoing pandemic. SARS-CoV-2 Orf6 antagonizes host interferon signaling by inhibition of mRNA nuclear export through its interactions with the ribonucleic acid export 1 (Rae1)–nucleoporin 98 (Nup98) complex. Here, we confirmed the direct tight binding of Orf6 to the Rae1-Nup98 complex, which competitively inhibits RNA binding. We determined the crystal structures of both SARS-CoV-2 and SARS-CoV-1 Orf6 C-termini in complex with the Rae1–Nup98 heterodimer. In each structure, SARS-CoV Orf6 occupies the same potential mRNA-binding groove of the Rae1–Nup98 complex, comparable to the previously reported structures of other viral proteins complexed with Rae1-Nup98, indicating that the Rae1–Nup98 complex is a common target for different viruses to impair the nuclear export pathway. Structural analysis and biochemical studies highlight the critical role of the highly conserved methionine (M58) of SARS-CoVs Orf6. Altogether our data unravel a mechanistic understanding of SARS-CoVs Orf6 targeting the mRNA-binding site of the Rae1–Nup98 complex to compete with the nuclear export of host mRNA, which further emphasizes that Orf6 is a critical virulence factor of SARS-CoVs.

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Floral organs are properly developed on the basis of timed floral meristem (FM) termination in Arabidopsis. In this process, two known regulatory pathways are involved. The WUSCHEL (WUS)-CLAVATA3 (CLV3) feedback loop is vital for the spatial establishment and maintenance of the FM, while AGAMOUS (AG)-WUS transcriptional cascades temporally repress FM. At stage 6 of flower development, a C2H2-type zinc finger repressor that is a target of AG, KNUCKLES (KNU), directly represses the stem cell identity gene WUS in the organizing center for FM termination. However, how the robust FM activity is fully quenched within a limited time frame to secure carpel development is not fully understood. Here, we demonstrate that KNU directly binds to the CLV1 locus and the cis-regulatory element on CLV3 promoter and represses their expression during FM determinacy control. Furthermore, KNU physically interacts with WUS, and this interaction inhibits WUS from sustaining CLV3 in the central zone. The KNU–WUS interaction also interrupts the formation of WUS homodimers and WUS–HAIRYMERISTEM 1 heterodimers, both of which are required for FM maintenance. Overall, our findings describe a regulatory framework in which KNU plays a position-specific multifunctional role for the tightly controlled FM determinacy.