P10, A low molecular weight single-stranded nucleic acid-binding protein of murine leukemia retroviruses, shows stacking interactions of its single tryptophan residue with nucleotide bases

Abstract

Room temperature fluorescence and low-temperature phosphorescence studies of the association of p10, a basic low molecular weight single-stranded DNA binding protein isolated from murine leukemia viruses, point to the involvement of its single tryptophan residue in a close-range interaction with single-stranded polynucleotides. Optically detected triplet-state magnetic resonance (ODMR) techniques applied to the complex of p10 protein with the heavy atom derivatized polynucleotide poly(5-HgU) demonstrate the occurrence of stacking interactions of Trp35 with nucleic acid bases, thus agreeing with earlier reports that this residue is involved in the binding process [Karpel, R. L., Henderson, L. E., & Oroszlan, S. (1987) J. Biol. Chem. 262, 4961-4967].

Specific binding of human immunodeficiency virus type 1 gag polyprotein and nucleocapsid protein to viral RNAs detected by RNA mobility shift assays

“…If tRNA was not included in the mixture, the fusion proteins migrated more slowly, indicating that these proteins were binding to the tRNA during the assay. This nonspecific binding is consistent with earlier work demonstrating that both gag polyproteins and nucleocapsid proteins bind nonspecifically to RNA in vitro (12,16,18,30,32,39,46,52,55,64).…”

“…However, a recent report on Rous sarcoma virus has shown that efficient RNA encapsidation can occur when both Cys-His boxes have been deleted from the gag polyprotein (4). In addition, although in vitro binding studies have consistently demonstrated that NC proteins bind to single-stranded nucleic acids (12,16,18,30,32,39,52,55,64), most studies have failed to identify sequence-specific binding (16,39,52,55,64). Recently, a gel mobility shift assay has been used to measure in vitro binding of purified bovine leukemia virus (BLV) gag proteins to BLV genomic RNA segments; in this report, NC was shown to bind to all RNA segments analyzed, whereas MA was shown to bind only to the RNA segment containing the BLV packaging element T (33).…”

Solid phase synthesis of the retro viral nucleocapsid protein NCp10 of Moloney Murine Leukaemia virus and related “zinc‐fingers” in free SH forms

“…Moreover, fluorescence studies showed an emission maximum at 350 nm, suggesting that the single tryptophan residue is probably solvent-exposed, in agreement with a previous report (29). Furthermore, the very low contribution of tyrosine fluorescence to the intrinsic protein fluorescence reflects an efficient energy transfer between Ty?'…”

Viral RNA annealing activities of the nucleocapsid protein of Moloney murine leukemia virus are zinc independent

“…To analyze the RNA binding and annealing activities of the modified NCplO proteins we have used MoMuLV RNA containing the primer binding site and the Psi element, that allow the specific annealing of the replication primer tRNA Pro and the selective dimerization and encapsidation of MuLV RNA, respectively (16,23,27). Previous in vitro studies have shown that cysteine modification of the zinc finger domain of NCplO does not affect its affinity for polyribonucleotides (6,40,41). However the biological relevance of these results remains questionable since non viral, synthetic RNAs have been used.…”