Autocatalytic processing of the potyvirus helper component proteinase in Escherichia coli and in vitro
Year: 1989
Type: article
Abstract: The virus-encoded proteins of tobacco etch virus (TEV), a plant potyvirus, arise by proteolytic processing of a large polyprotein precursor. The TEV genome codes for two proteinases, a 49-kilodalton proteinase and helper component proteinase (HC-Pro), which cleave the polyprotein at specific sites. The only known cleavage event catalyzed by HC-Pro occurs at the HC-Pro carboxyl terminus. The proteolytic activity of HC-Pro was analyzed by expression of the enzyme in bacterial and cell-free systems. The carboxyl-terminal domain of HC-Pro exhibited proteolytic activity in Escherichia coli with a processing half-time of approximately 100 s. The processing kinetics of HC-Pro expressed in vitro by cell-free transcription and translation was variable, depending on the presence or absence of TEV polypeptide sequences at the amino terminus of the proteolytic domain. Cleavage of the HC-Pro carboxyl terminus appeared to proceed exclusively by an autocatalytic mechanism; the proteinase synthesized in vitro exhibited little or no proteolytic activity when reacted with the HC-Pro cleavage site in trans or biomolecular reactions.
Source: Journal of Virology
Authors: J C Carrington, D D Freed, T C Sanders
Institution: Texas A&M University
Language: English
Topic: Plant Virus Research Studies
Subfield: Plant Science
Domain: Life Sciences
Open Access status: bronze
Award: G1510665060
OpenAlex ID: W1480753383