No abstract

Redundancy of signal transduction elements, parallelisms of pathways, and conditionally alternative mechanisms generate a robust network and system that only tentatively can be assessed by use of single-site mutants. Antioxid. Redox Signal. 00, 000-000.

About three decades ago, researchers suggested that metabolic enzymes participate in cellular processes that are unrelated to their catalytic activity, and the term moonlighting functions was proposed. Recently developed advanced technologies in the field of RNA interactome capture now unveil the unexpected RNA binding activity of many metabolic enzymes, as exemplified here for the enzymes of glycolysis. Although for most of these proteins precise binding mechanism, binding conditions and physiological relevance of the binding events still awaits in depth clarification, several well-explored examples demonstrate that metabolic enzymes hold crucial functions in post-transcriptional regulation of protein synthesis. This widely conserved RNA-binding function of glycolytic enzymes plays major roles in controlling cell activities. Best-explored examples are glyceraldehyde 3-phsohphate dehydrogenase, enolase, phosphoglycerate kinase and pyruvate kinase. This review summarizes the current knowledge about the RNA-binding activity of the ten core enzymes of glycolysis in plant, yeast and animal cells, its regulation and physiological relevance. Apparently, a tight bidirectional regulation connects core metabolism and RNA biology forcing us to rethink long-established functional singularities.

Canonical retrograde signaling is the transmission of information from organelles to the nucleus. Discrepancies between protein accumulation and transcript abundance in response to oxidative stress were suggestive of protein translation responding to retrograde signaling. Here we uncover multiple components of a translation-dependent retrograde signaling pathway that impact translation efficiency and gene expression, including the kinases, MPK6 and the SnRK1 subunit, AKIN10. Global ribosome foot-printing demonstrated rapid differential loading of 939 of transcripts from polyribosomes within 10 min after transfer from Low to High-light. Translationally regulated transcripts shared motifs in their 5`-UTR that act as binding sites for RBPs such as GAPC. The Stress Associated Proteins 2 and 3 carry such motifs in their UTRs and interact with the calcium sensor Calmodulin-like 49, relocating to the nucleus to co-regulate a translation-dependent transcriptional response. Translation dependent retrograde signaling bifurcates into a direct translational circuit and a translation-reliant nuclear circuit synchronizing translation, nuclear and anterograde response pathways, which may serve as a just in time-provision of needed proteins to the plastids.