PCNA interacts with Indian mung bean yellow mosaic virus rep and downregulates Rep activity.
Proliferative cell nuclear antigen (PCNA), a conserved plant protein as well as an important replication factor, is induced in response to geminivirus infection in the resting cells of the phloem tissues. The biochemical role of PCNA in rolling circle replication (RCR) of geminivirus DNA has not been explored in detail. The initiation of RCR of the bipartite genome of a geminivirus, Indian mung bean yellow mosaic virus (IMYMV), is mainly controlled by viral protein Rep (or AL1 or AC1). The role of host PCNA in RCR of IMYMV was revealed by studying the physical and functional interactions between recombinant PCNA and recombinant IMYMV Rep. Pea nuclear PCNA as well as recombinant pea PCNA showed binding to recombinant Rep in experiments involving both affinity chromatography and yeast two-hybrid approaches. The contacting amino acid residues of PCNA seemed to be present throughout a wide region of the trimeric protein, while those of Rep appeared to be localized only in the middle part of the protein. The site-specific nicking-closing activity and the ATPase function of IMYMV Rep were impaired by PCNA. These observations lead to interesting speculations about the control of viral RCR and dynamic profiles of protein-protein interactions at the RCR origin of the geminiviruses.
Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India.
Basavaraj
B
Bagewadi
Shoajiang
S
Chen
Sunil K
SK
Lal
Nirupam Roy
NR
Choudhury
Sunil K
SK
Mukherjee
D001665:Binding Sites; D004261:DNA Replication; D015536:Down-Regulation; D007887:Fabaceae / Q000821:virology*; D017791:Geminiviridae / Q000502:physiology*; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology*
D018809:Proliferating Cell Nuclear Antigen; D011994:Recombinant Proteins; D014764:Viral Proteins; C080288:replication protein AL1, Begomovirus