Diverse RNA-Binding Proteins Interact with Functionally Related Sets of RNAs, Suggesting an Extensive Regulatory System

RNA-binding proteins (RBPs) have roles in the regulation of many post-transcriptional steps in gene expression, but relatively few RBPs have been systematically studied. We searched for the RNA targets of 40 proteins in the yeast Saccharomyces cerevisiae: a selective sample of the approximately 600 annotated and predicted RBPs, as well as several proteins not annotated as RBPs. At least 33 of these 40 proteins, including three of the four proteins that were not previously known or predicted to be RBPs, were reproducibly associated with specific sets of a few to several hundred RNAs. Remarkably, many of the RBPs we studied bound mRNAs whose protein products share identifiable functional or cytotopic features. We identified specific sequences or predicted structures significantly enriched in target mRNAs of 16 RBPs. These potential RNA-recognition elements were diverse in sequence, structure, and location: some were found predominantly in 3′-untranslated regions, others in 5′-untranslated regions, some in coding sequences, and many in two or more of these features. Although this study only examined a small fraction of the universe of yeast RBPs, 70% of the mRNA transcriptome had significant associations with at least one of these RBPs, and on average, each distinct yeast mRNA interacted with three of the RBPs, suggesting the potential for a rich, multidimensional network of regulation. These results strongly suggest that combinatorial binding of RBPs to specific recognition elements in mRNAs is a pervasive mechanism for multi-dimensional regulation of their post-transcriptional fate

Maltose-binding protein switches programmed cell death in Nicotiana glutinosa leaf cells

Maltose-binding protein (MBP) is a part of the complex regulatory and transport maltose system of Escherichia coli that is responsible for the uptake and efficient catabolism of maltodextrins through the trans-membrane signaling at the expense of ATP. In the present work, this bacterial periplasmic protein was identified as a cell death inducer in Nicotiana glutinosa plant. Upon exogenous application at the concentrations more than 50 μg/mL, purified MBP protein induced wilting and localized cell death on the leaves of test plant. DNA fragmentation assay and antioxidant enzymes activity test showed that the induced cell death might be programmed. It was predicted that maltose-binding protein signals programmed cell death (PCD) upstream of reactive oxygen species (ROS) and DNA fragmentation processes in the test plant leaves. However, it needs to be clarified that how MBP switches and signals PCD in plant tissues.Белок, связывающий мальтозу (МСБ), является частью сложной системы регуляции и транспорта мальтозы у Escherichia coli. Он отвечает за поглощение и эффективный катаболизм мальтозы с помощью трансмембранной передачи сигнала за счет АТФ. В настоящей работе показано, что этот бактериальный перипластный белок является индуктором клеточ-ной гибели у Nicotiana glutinosa. При экзогенном нанесении в концентрациях более чем 50 мг/мг очищенный МСБ индуцирует увядание и локали-зованную клеточную гибель в листьях тестовых растений. Анализ фрагментации ДНК и активности антиоксидантных ферментов показал, что индуцированная гибель клеток может быть запрограммированной. Предполагается, что МСБ может влиять на развитие программированной клеточной гибели через сигналинг активных форм кислорода и регуляцию процессов фрагментации ДНК в листьях тестовых растений, однако механизм такого воздействия подлежит дальнейшему исследованию