Possible roles of HIV-1 nucleocapsid protein in the specificity of proviral DNA synthesis and in its variability.

Retroviral nucleocapsid (NC) protein is an integral part of the virion nucleocapsid where it coats the dimeric RNA genome. Due to its nucleic acid binding and annealing activities, NC protein directs the annealing of the tRNA primer to the primer binding site and greatly facilitates minus strand DNA elongation and transfer while protecting the nucleic acids against nuclease degradation. To understand the role of NCp7 in viral DNA synthesis, we examined the influence of NCp7 on self-primed versus primer-specific reverse transcription.

First glimpses at structure-function relationships of the nucleocapsid protein of retroviruses.

Retroviruses are a family of widespread small animal viruses about 110 nm in diameter, composed of an inner core surrounded by an outer envelope formed of a lipid bilayer of cellular origin in which are anchored viral glycoproteins. The inner core is formed by an outer shell of capsid protein molecules (CA protein) surrounding the dimeric RNA genome in close association with about 2000 molecules of nucleocapsid protein (NC protein) and molecules of reverse transcriptase (RT) and integrase (IN). Conversion of the genomic single-stranded RNA into a double-stranded proviral DNA by RT takes place in the nucleocapsid substructure and involves two DNA strand transfers to generate the long terminal repeats (LTR) required for IN-mediated integration of the proviral DNA into the cellular genome and its expression.

Analysis of the nucleic acid annealing activities of nucleocapsid protein from HIV-1.

Retroviral nucleocapsid (NC) protein is an integral part of the virion nucleocapsid where it is in tight association with genomic RNA and the tRNA primer. NC protein is necessary for the dimerization and encapsidation of genomic RNA, the annealing of the tRNA primer to the primer binding site (PBS) and the initial strand transfer event. Due to the general nature of NC protein-promoted annealing, its use to improve nucleic acid interactions in various reactions can be envisioned.

Properties of the lysyl-tRNA synthetase gene and product from the extreme thermophile Thermus thermophilus.

A DNA region carrying lysS, the gene encoding the lysyl-tRNA synthetase, was cloned from the extreme thermophile prokaryote Thermus thermophilus VK-1 and sequenced. The analysis indicated an open reading frame encoding a protein of 492 amino acids. This putative protein has significant homologies to previously sequenced lysyl-tRNA synthetases and displays the three motifs characteristic of class II aminoacyl-tRNA synthetases.

Transactivation of the minus-strand DNA transfer by nucleocapsid protein during reverse transcription of the retroviral genome.

Two DNA strand transfers are required during reverse transcription of the RNA genome of retroviruses to complete provirus synthesis. To understand more about the first strand transfer reaction, that of the minus-strand DNA from the 5' to the 3' end of the retroviral genome, we devised an in vitro system mimicking the Moloney murine leukemia virus reverse transcription process. Two RNAs corresponding to the 5' and 3' regions of the genome were used to perform reverse transcription assays.