The HIV-1 capsid protein forms the conical core structure at the center of the mature virion. Capsid also binds the human peptidyl prolyl isomerase, cyclophilin A, thereby packaging the enzyme into the virion. Cyclophilin A subsequently performs an essential function in HIV-1 replication, possibly helping to disassemble the capsid core upon infection. We report the 2.36 A crystal structure of t...

Molecular dynamics simulation of an atom-resolved bacteriophage P22 capsid model is used to delineate the underlying mechanism of early stage P22 self-assembly. A dimer formed by the C-terminal fragment of scaffolding protein with a new conformation is demonstrated to catalyze capsomer (hexamer and pentamer) aggregation efficiently. Effects of scaffolding protein/coat protein binding patterns a...

The in vivo incorporation of exogenous radioactive acetate into two proteins of Sindbis virus, the capsid protein and PE2, is described. Under appropriate labeling conditions, 40-50% of the label in the capsid protein is found in an N-acetyl group which constitutes the NH2-terminal modification of this blocked protein. The incorporated radiolabeled acetate was useful in the purification and ana...

To further characterize the nature of proteolytic processing of the astrovirus capsid, we infected Caco-2 cells with a high multiplicity of astrovirus without trypsin in the presence of 5 to 10% fetal calf serum. These infections were characterized by pulse-chase labeling with [35S]Smethionine, electron microscopy, gel electrophoresis of purified viral particles, and analysis of infectivity of ...

The formation of a protective protein container is an essential step in the life-cycle of most viruses. In the case of single-stranded (ss)RNA viruses, this step occurs in parallel with genome packaging in a co-assembly process. Previously, it had been thought that this process can be explained entirely by electrostatics. Inspired by recent single-molecule fluorescence experiments that recapitu...

Following human immunodeficiency virus (HIV-1) entry into the host cell, the viral capsid gradually disassembles in a process called uncoating. A proper rate of uncoating is important for reverse transcription of the HIV-1 genome. Host restriction factors such as TRIM5α and TRIMCyp bind retroviral capsids and cause premature disassembly, leading to blocks in reverse transcription. Other host fa...

Purified intact Sindbis virus nucleocapsids were treated at different pH values or with various concentrations of divalent cations, cation chelators, salt, or formamide. The resulting structures were examined by velocity sedimentation, electron microscopy, and protein-protein cross-linking. Changes in each of the test conditions led to alterations in the sedimentation profile of treated nucleoc...

Upon entering a cell, alphaherpesvirus capsids are transported toward the minus ends of microtubules and ultimately deposit virus DNA within the host nucleus. The virus proteins that mediate this centripetal transport are unknown but are expected to be either viral tegument proteins, which are a group of capsid-associated proteins, or a surface component of the capsid itself. Starting with deri...

We have cloned and sequenced the cDNA made to the region of RNA encoding the structural proteins of three complementation group C mutants of Sindbis virus, ts2, ts5, and ts13, and of their revertants. These mutants possess defects in the posttranslational processing of their structural proteins at the nonpermissive temperature. Comparison of the deduced amino acid sequences of the mutants with ...