Summary auto-generated
This study investigated the protein interactions of potato A potyvirus (PVA) using the yeast two-hybrid system. The researchers examined the previously proposed homodimerization of helper component-proteinase (HC-Pro) and its potential interaction with coat protein (CP). Results demonstrated that HC-Pro self-associates in vivo, forming homodimers, and that CP also undergoes self-interaction. Deletion analysis identified two critical domains for HC-Pro self-association: a 24 amino acid stretch in the N-terminal region and the C-terminal proteinase domain. Notably, no interactions were detected between HC-Pro and CP from either aphid-transmissible or non-transmissible PVA strains, contradicting the prevailing hypothesis that direct HC-Pro–CP interaction is required for aphid transmission. The findings confirm that functional HC-Pro likely exists as a dimer, supporting earlier biochemical observations, though the biological significance of this homodimerization remains unclear. The inability to detect HC-Pro–CP interaction in PVA contrasts with reports from other potyviruses, suggesting this interaction may not be universal.
Key findings
- HC-Pro and coat protein both form homodimers through self-association in yeast cells, confirmed by two-hybrid system analysis
- HC-Pro self-interaction requires two key domains: a 24 amino acid N-terminal region and the C-terminal proteinase domain
- No direct interaction between HC-Pro and coat protein was detected in PVA, either from aphid-transmissible or non-transmissible strains
- HC-Pro likely functions as a homodimer in its biological roles, supporting previous biochemical proposals
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Abstract
Potyviral helper component-proteinase (HC-Pro) is a multifunctional protein involved in aphid transmission, long-distance movement, polyprotein processing, genome amplification and symptom expression. It has been proposed that the active form of HC-Pro is a dimer and that coat protein (CP)--HC-Pro interaction is required for aphid transmission. To test these proposed interactions between CP and HC-Pro of potato A potyvirus (PVA), the yeast two-hybrid system was used. HC-Pro was shown to interact with itself in vivo in yeast cells, as did CP. Taken together with previous observations, we conclude that the functional HC-Pro is a homodimer. Deletion analysis showed that a 24 aa domain in the N-terminal half and the C-terminal proteinase part of HC-Pro were required for the interaction between HC-Pro molecules. No interactions were found between HC-Pro and CP using the genes of aphid-transmissible as well as aphid non-transmissible strains of PVA.