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Human Ribosomal Protein L7 Binds RNA with an α‐Helical Arginine‐Rich and Lysine‐Rich Domain

1997; Wiley; Volume: 245; Issue: 3 Linguagem: Inglês

10.1111/j.1432-1033.1997.00549.x

1432-1033

Peter Hemmerich, Stefan Bosbach, Anna von Mikecz, Ulrich Krawinkel,

RNA modifications and cancer

In this study we mapped the RNA‐binding domain of human ribosomal protein L7 and characterized its conformation‐dependent RNA‐binding specificity. Binding competition assays demonstrated preferential binding of L7 to mRNAs and rRNA, but not to tRNA. The ribohomopolymer poly(G) is bound with high affinity whereas poly(U), poly(C), or poly(A) show low affinity to L7. Furthermore, L7 binds to double‐stranded but not to single‐stranded DNA. Deletion mapping showed that the RNA‐binding domain of L7 is represented by an arginine‐rich and lysine‐rich oligopeptide (ELKIKRLRKKFAQKMLRK‐ARRK), which is reminiscent of the arginine‐rich motif (ARM) found in one family of RNA‐binding proteins. The isolated RNA‐binding domain is capable of high‐affinity binding to the Rev‐responsive element (RRE) of human immunodeficiency virus type 1 in vitro. Circular dichroic studies demonstrated a concentration‐dependent and ligand‐induced α‐helical transition of a synthetic peptide carrying the arginine‐lysine‐rich RNA‐binding domain of protein L7. Peptides carrying a mutation that destroys the α‐helical conformation do not bind RNA.