Professor Denis Archambault of the Department of Biological Sciences of Universit- du Qu-bec - Montr-al (UQAM), and doctoral student Andrea Corredor Gomez have made a major discovery in the field of molecular biology. They have unlocked some of the secrets of a viral protein, known as Rev, which is very different from other proteins of the same type studied to date. The results of their research were recently published in the prestigious Journal of Virology.
The Rev protein plays an essential role in the propagation mechanism of certain types of viruses within an organism. The work of researchers Archambault and Gomez Corredor focused on this protein, and more particularly on a structure called the "nuclear localization signal" (NLS). They used as a model the Rev protein of the bovine immunodeficiency virus (BIV), a retrovirus related to the AIDS virus in humans.
Retroviruses, like all other viruses, are characterized by an inability to multiply on their own. In order to reproduce, they require a living host cell. A cell has a cytoplasm and a nucleus at the centre. The nucleus contains nucleoli, or sub-compartments. It was already known that the Rev protein, produced in the cytoplasm, moves into the nucleus and nucleoli of a cell infected with certain retroviruses. By binding to the viral RNAs found in the nucleus, it contributes to the transition of an infection from the early to the late stage. To fulfil this primary function, the Rev protein must first be able to enter the nucleus. To do so, it needs a "key", its "NLS" composed of amino acids.
A different nuclear localization signal (NLS)
Over the years, several researchers have looked at the NLS in different Rev proteins. Until now, the study of these proteins demonstrated the presence of a monopartite NLS, i.e. an NLS comprising one continuous sequence of amino acids. Much to their surprise, Denis Archambault and Andrea Gomez Corredor discovered that the BIV Rev protein has a bipartite NLS - composed of two amino acid motifs separated by a sequence of additional amino acids - a world first for this type of protein in all retroviruses studied to date, including the AIDS virus.