The rubella virus nonstructural protease recognizes itself via an internal sequence present upstream of the cleavage site for trans-activity.
The substrate requirement for rubella virus protease trans-activity is unknown. Here, we analyzed the cleavability of RV P200-derived substrates varying in their N-terminal lengths (72-475 amino acids) from the cleavage site by the RV protease trans-activity. Only substrates with at least 309 amino acid residues N-terminal to the cleavage site were able to undergo cleavage. Further, rubella sequence was found to be necessary in the N-terminal region of the substrate, whereas a heterologous sequence C-terminal to the cleavage site was tolerated. These results demonstrated a requirement for residues located between amino acids 994-1102 of the RV P200 polyprotein, besides its cleavage site for RV protease trans-activity. This region overlaps with the starting site of the essential cis-protease activity of RV P200 polyprotein. This is a novel observation for a viral protease of the family Togaviridae.
Chen
H H
HH
Division of Viral Products, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Bethesda, Maryland 20892, USA.
Stark
C J
CJ
Atreya
C D
CD
D001665:Binding Sites; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D020815:Polyproteins / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D012412:Rubella virus / Q000201:enzymology* / Q000502:physiology; D017384:Sequence Deletion; D013379:Substrate Specificity; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000378:metabolism*
D020815:Polyproteins; D017361:Viral Nonstructural Proteins; D010447:Peptide Hydrolases