Initiation of encapsidation as evidenced by deoxycholate-treated Nucleocapsid protein in the Chandipura virus life cycle.
Encapsidation of nascent genome RNA into an RNase-resistant form by nucleocapsid protein, N is a necessary step in the rhabdoviral life cycle. However, the precise mechanism for viral RNA specific yet processive encapsidation remains elusive. Using Chandipura virus as a model system, we examined RNA binding specificity of N protein and dissected the biochemical steps involved in the rhabdoviral encapsidation process. Our analysis suggested that N protein in its monomeric form specifically binds to the first half of the leader RNA in a 1:1 complex, whereas, oligomerization imparts a broad RNA binding specificity. We also observed that viral P protein and dissociating detergent deoxycholate, both were able to maintain N in a monomeric form and thus promote specific RNA recognition. Finally, use of a minigenome length RNA in an in vitro encapsidation assay revealed the monomeric N and not its oligomeric counterpart, to be the true encapsidating unit. Based on our observations, we propose a model to explain encapsidation that involves two discrete biochemically separable steps, initiation and elongation.
Dr. B.C. Guha Centre for Genetic Engineering and Biotechnology, Department of Biochemistry, University College of Science, University of Calcutta, Calcutta 700 019, India.
Raja
R
Bhattacharya
Soumen
S
Basak
D J
DJ
Chattopadhyay
D020121:5' Untranslated Regions / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003840:Deoxycholic Acid / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D018832:Molecular Chaperones; D019590:Nucleocapsid Proteins / Q000502:physiology*; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D012367:RNA, Viral / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000502:physiology; D012260:Ribonucleases / Q000378:metabolism; D018116:Vesiculovirus / Q000502:physiology*; D014764:Viral Proteins / Q000502:physiology; D015678:Viral Structural Proteins / Q000378:metabolism; D019065:Virus Assembly / Q000502:physiology*
D020121:5' Untranslated Regions; D003902:Detergents; D018832:Molecular Chaperones; C096112:NV protein, Rhabdovirus; D019590:Nucleocapsid Proteins; C412837:P protein, Chandipura virus; D010750:Phosphoproteins; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D014764:Viral Proteins; D015678:Viral Structural Proteins; D003840:Deoxycholic Acid; D012260:Ribonucleases