Conclusions
Acid-labile formylation of N-terminal proline of HIV-1 p24gag was found by proteomics. The role of formylation of human immunodeficiency virus type 1 p24gag is unclear so far, but it is surmised that the acid-labile formylation of HIV-1LAV-1 p24gag may play a critical role in the formation of the HIV-1 core for conferring HIV-1 infectivity. Furthermore, peptide-mass fingerprinting data suggest that two isoforms of cyclophilin A (CyPA), one with an isoelectric point (pI) of 6.40 and one with a pI of 6.53, are inside the viral membrane and another isoform with a pI of 6.88 is outside the viral membrane, and that the CyPA isoform with a pI of 6.53 is N-acetylated. The mechanisms that permit the redistribution of CyPA on the viral surface have not yet been clarified, but it is surmised that the CyPA isoform with a pI of 6.88 may play a critical role in the attachment of virions to the surface of target cells, and both the CyPA isoforms with pIs of 6.40 and 6.53 may regulate the conformation of the HIV-1 capsid protein.
Proteome analysis of HIV-1LAV-1 is very useful in understanding biological phenomena at the molecular level by identifying new proteins and co/post-translational modifications that are indispensable to viral replication, and in finding out attractive targets for the future AIDS-therapies.