Title: Evidence for lysine acetylation in the coat protein of a Polerovirus Authors
|Johnson, Richard -|
|Sweeney, Michelle -|
|Bruce, James -|
|Maccoss, Michael -|
Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 13, 2014
Publication Date: N/A
Interpretive Summary: Proteins are tiny molecular machines essential for life. The shape and function of a protein will be determined by its amino acid building block composition and the way in which the amino acids come together in three dimensional space. Often, proteins chemically modify each other’s amino acids in such a way that changes their shape and function – a process called posttranslational modification. Posttranslational modification is one way to expand the functional repertoire of a protein. Virus capsids are molecular machines made primarily out of proteins. From a virus’s perspective, the most important function of the capsid is to protect its genetic material during plant infection and insect transmission. The outside shape of a virus capsid determines whether a virus will be transmitted by an insect and infect a specific plant. This research shows the first evidence of a posttranslational modification on the capsid of an insect-transmitted plant virus, cereal yellow dwarf virus (CYDV-RPV). CYDV-RPV infects a range of cereal crops including oats, barley, and wheat and is related to other viruses infecting crops such as potato, maize, beans, and sugarcane, among others. Evidence supports the hypothesis that this capsid posttranslational modification makes the capsid stronger. This work is important because understanding how plant viruses use posttranslational modifications to protect their capsids will enable us to develop novel disease control strategies in many agriculturally-important crops in the USA and world-wide.
Technical Abstract: Virions of the RPV strain of Cereal yellow dwarf virus (CYDV-RPV) were purified from infected oat tissue and analyzed by mass spectrometry. Two conserved residues, K147 and K181, residing in the virus coat protein, were confidently identified to contain epsilon-N-acetyl groups. While no functional data are available for K147, K181 lies within an interfacial region critical for virion assembly and stability. The signature immonium ion at m/z (mass-to-charge) 126.0919 demonstrated the presence of N-acetyllysine, and the sequence fragment ions enabled an unambiguous assignment of the epsilon-N-acetyl modification on K181. We hypothesize that acetylation is a molecular signature of host-pathogen conflict, where the virus favors selective modification of K181 to stabilize the virus by promoting intermonomer salt bridge formation.