Summary auto-generated
Beet yellows closterovirus (BYV) encodes a 65 kDa protein (p65) related to cellular HSP70 heat shock chaperones. Researchers produced purified recombinant BYV p65 and various truncated fragments in bacteria and characterized their biochemical properties. The full-length p65 protein and its N-terminal fragments demonstrated magnesium-dependent ATPase activity in vitro, with the activity localized to the N-terminal 40 kDa region. However, unlike cellular HSP70 chaperones, purified p65 failed to bind denatured proteins or synthetic peptides and was not stimulated by peptides known to activate HSP70 ATPases. Using polyclonal antibodies against p65, the researchers detected expression of the viral protein in BYV-infected plants, where it localized to cytoplasm, membranes, nuclei, and cell walls. These findings suggest that although p65 possesses a functional ATPase domain similar to HSP70, it has divergent substrate specificity and likely performs a distinct cellular function in infected plants, possibly related to viral transport rather than general protein folding.
Key findings
- BYV p65 possesses magnesium-dependent ATPase activity localized to its conserved N-terminal domain, similar to HSP70 chaperones
- p65 does not bind unfolded proteins or synthetic peptides, and its ATPase activity is not stimulated by peptides that activate cellular HSP70s
- p65 is expressed during BYV infection in plants and localizes to multiple subcellular compartments including cytoplasm, membranes, and cell walls
- The C-terminal domain of p65 is structurally distinct from HSP70 peptide-binding domains, suggesting evolution of different substrate specificity
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
The positive-strand RNA genome of beet yellows closterovirus (BYV) encodes a 65 kDa protein (p65) related to the HSP70 family of cell chaperones. The full-sized BYV p65, and N- and C-terminal fragments, with (His)6 tails, were overexpressed in bacteria and purified by metal- chelate chromatography. Using a polyclonal antiserum raised against the C-terminal fragment of p65, evidence was obtained for expression of the viral protein in planta. Purified recombinant p65 and its N-terminal 40 kDa fragment exhibited Mg2+-dependent ATPase activity in vitro. However, unlike its cellular HSP70 homologues, p65 was unable to bind to denatured protein and its ATPase activity was not stimulated by synthetic peptides which are known to stimulate HSP70 ATPases. Hence, the BYV p65, although being a chaperone-type ATPase, may have a distinct substrate specificity and function in BYV-infected cells.