Thermus thermophilus bacteriophage P23-45 encodes a giant 5,002-residue tail tape measure protein (TMP) that defines the length of its extraordinarily long 800 nm tail. We found that the N-terminal portion of P23-45 TMP is an unusual RNA polymerase (RNAP) homologous to cellular and viral two-barrel RNAPs. The TMP-fused virion RNAP transcribes pre-early phage genes, including a gene that encodes another, non-virion RNAP, that transcribes early and some middle phage genes. We determined the crystal structures of both P23-45 RNAPs. The non-virion RNAP has a crab claw-like architecture similar to previously reported two-barrel RNAPs. The virion RNAP adopts a unique flat structure without a clamp, which likely reflects the requirement for its extrusion through the narrow channel in the phage tail for delivery into the cell. Structure and sequence comparisons of the P23-45 RNAPs with other phage and cellular RNAPs suggest that, despite the extensive functional differences, the two P23-45 RNAPs originate from an ancient gene duplication in an ancestral phage. Our findings demonstrate remarkable adaptability of two-barrel RNAPs that can be attained within a single virus species.
In order to save time and money for tourists, as well as taking into account their limited mobility in the conditions of Covid, the concept of an intelligent guide based on augmented reality (AR) is proposed. A UML method diagram and algorithm for communication of the system with the user with AR and voice control support have been developed, as well as an application that allows tourists to immerse themselves in the historical retrospective of recreational places. On the example of the central part (downtown) of Ternopil, Ukraine, AR locations are offered, which gives an opportunity to get acquainted in more detail with the information about the tourist object. At the same time, the shortest tourist route is illuminated of historical monuments.
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