A tale of coupling, Sus1 function in transcription and mRNA export.

Eukaryotic cells have evolved unveiling a tightly coupled scenario between transcription, RNA biogenesis and mRNA transport out of the nucleus. Gene expression regulation relies partially on the action of some protein complexes, which ensure that all these processes work co-ordinately in order to achieve an optimal performance. The evolutionarily conserved export factor Sus1 plays a key role in coupling transcription activation with mRNA export as part of the nuclear pore associated complex TREX2 and the transcriptional coactivator SAGA. Being a factor shared by these two complexes, Sus1 physically link the activated GAL1 gene to the nuclear periphery, which constitute a determinant of regulation. An exciting new study has expanded our knowledge of Sus1 function. Sus1 is required for transcription elongation, it's recruited to coding regions and interacts with different factors during mRNA biogenesis. Moreover, SAGA and TREX2 are necessary for efficient Sus1 recruitment to chromatin. These results underscore the key role of Sus1 coordinating gene transcription coupled to mRNA export.