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.
Bhattacharya
Raja
R
Dr. B.C. Guha Centre for Genetic Engineering and Biotechnology, Department of Biochemistry, University College of Science, University of Calcutta, Calcutta 700 019, India.
Basak
Soumen
S
Chattopadhyay
D J
DJ
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