Viral control of translation: rise of the ribosome.

Viruses have evolved a myriad of strategies to manipulate their host's protein synthesis machinery, studies of which uncovered many founding principles of translational control. Decades of research have established our now-extensive understanding of how these pathogens target the array of translation factors that recruit ribosomes and regulate scanning, start site selection, decoding, and termination. Meanwhile, the ribosome itself was largely regarded as a code-reading machine that lacks regulatory influence. Recent advances in cryo-electron microscopy and quantitative proteomics have upended this viewpoint by revealing the remarkable conformational and compositional plasticity that gives rise to functionally diverse and translationally selective ribosome populations in mammalian cells. Here, we discuss how viruses are once again at the forefront of this emerging field, often bypassing or rewiring host translation factors while directly controlling the ribosome's composition and intrinsic motions to selectively promote their non-canonical modes of translation. We offer cautionary perspectives on extra-ribosomal functions of ribosomal proteins, while highlighting the emergence of the 40S head domain as a dynamic platform targeted to control various translation processes, ranging from initiation to frameshifting, that expand viral coding capacity. Overall, we chart the rise of the ribosome from a passive player to an active regulatory hub at the center of viral translational control strategies.