Cellular proteins bind to multiple sites of the leader region of cauliflower mosaic virus 35S RNA.

UV crosslinking assays were performed to characterize interactions between the leader of the cauliflower mosaic virus (CaMV) 35S RNA and cellular, cytoplasmic proteins. From turnip, a host for CaMV, three different proteins, p35, p49, and p100, interacted with multiple binding sites within the leader p35 binds to RNA nonspecifically and p49 binds with low specificity, whereas p100 interacts specifically with viral sequences. The expression of the proteins is not induced upon virus infection, as there is no difference in the protein pattern between healthy and infected cell extracts. In a cellular fractionation, p35 and p100 remain in the high-speed supernatant whereas p49 cosediments with polysomes. A possible involvement of these proteins in the translation of the CaMV 35S RNA is discussed.