CATH Classification

Domain Context

CATH Clusters

Superfamily Helper component proteinase
Functional Family

Enzyme Information
Nuclear-inclusion-a endopeptidase.
based on mapping to UniProt P89509
Hydrolyzes glutaminyl bonds, and activity is further restricted by preferences for the amino acids in P6 - P1' that vary with the species of potyvirus, e.g. Glu-Xaa-Xaa-Tyr-Xaa-Gln-|-(Ser or Gly) for the enzyme from tobacco etch virus. The natural substrate is the viral polyprotein, but other proteins and oligopeptides containing the appropriate consensus sequence are also cleaved.
-!- The potyviruses cause diseases in plants, and inclusion bodies appear in the host cell nuclei, protein a of these being the endopeptidase. -!- The enzyme finds practical use when encoded in vectors for the artificial expression of recombinant fusion proteins, since it can confer on them the capacity for autolytic cleavage. -!- It is also reported that transgenic plants expressing the enzyme are resistant to viral infection. -!- Belongs to peptidase family C4.
Helper-component proteinase.
based on mapping to UniProt P89509
Hydrolyzes a Gly-|-Gly bond at its own C-terminus, commonly in the sequence -Tyr-Xaa-Val-Gly-|-Gly, in the processing of the potyviral polyprotein.
-!- Known from many potyviruses. -!- The helper component-proteinase of the tobacco etch virus is a multifunctional protein with several known activities. -!- The N-terminal region is required for aphid transmission and efficient genome amplification, the central region is required for long-distance movement in plants, and the C-terminal domain has cysteine endopeptidase activity. -!- Belongs to peptidase family C6.
RNA-directed RNA polymerase.
based on mapping to UniProt P89509
Nucleoside triphosphate + RNA(n) = diphosphate + RNA(n+1).
-!- Catalyzes RNA-template-directed extension of the 3'-end of an RNA strand by one nucleotide at a time. -!- Can initiate a chain de novo. -!- See also EC
Acting on ATP; involved in cellular and subcellular movement.
based on mapping to UniProt P89509
Acting on peptide bonds (peptidases).
based on mapping to UniProt P89509

UniProtKB Entries (1)

Turnip mosaic virus
Genome polyprotein

PDB Structure

External Links
Primary Citation
Structure of the autocatalytic cysteine protease domain of potyvirus helper-component proteinase
Guo, B., Lin, J., Ye, K.
to be published