Репозиторий Университета

© 2020 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM) Apart from being a conduit for photoassimilate transport in plants, the phloem serves as a pathway for transport of proteins and RNAs from sites of their synthesis to distant plant parts. As demonstrated for mRNAs and small RNAs such as miRNA and siRNA, their phloem transport is largely involved in responses to environmental cues including stresses and pathogen attacks. RNA molecules are believed to be transported in the phloem in the form of complexes with RNA-binding proteins; however, proteins forming such complexes are generally poorly studied. Here, we demonstrate that the Cucurbita maxima phloem serpin-1 (CmPS1), which has been previously described as a functional protease inhibitor capable of long-distance transport via the phloem, is able to bind RNA in vitro. Among different RNAs tested, CmPS1 exhibits a preference for imperfect RNA duplexes and the highest affinity to tRNA. A characteristic complex formed by CmPS1 with tRNA is not observed upon CmPS1 binding to tRNA-like structures of plant viruses. Mutational analysis demonstrates that the CmPS1 N-terminal region is not involved in RNA binding. Since antithrombin-III, the human protease inhibitor of serpin family most closely sequence-related to CmPS1, is found to be unable to bind RNA, one can suggest that, in its evolution, CmPS1 has gained the RNA binding capability as an additional function likely relevant to its specific activities in the plant phloem.

© 2019 The Author(s) The phloem sieve elements (SEs), enucleate cells, contain RNAs, which are imported from surrounding tissues and cells, mostly companion cells tightly associated with SEs, and transported via the phloem over the whole plant body. The RNA phloem transport is essential for plant individual development and responses to environmental cues. Recently, we identified primary miRNA (pri-miRNA) sequences in de novo assembled transcriptome of Cucurbita maxima phloem sap and reported 11 most abundant pri-miRNAs [1]. Here, we provide the output of this analysis in complete detail. For the full set of pri-miRNAs identified in the C. maxima phloem sap transcriptome, data on relative abundance are provided along with annotated sequence data.