A single amino acid change in a geminiviral Rep protein differentiates between triggering a plant defence response and initiating viral DNA replication.
We have devised an in planta system for functional analysis of the replication-associated protein (Rep) of African cassava mosaic virus (ACMV). Using this assay and PCR-based random mutagenesis, we have identified an ACMV Rep mutant that failed to trigger the hypersensitive response (HR), but had an enhanced ability to initiate DNA replication. The mutant Rep-green fluorescent protein (GFP) fusion protein was localized to the nucleus. Sequence analysis showed that the mutated Rep gene had three nucleotide changes (A6-->T, T375-->G and G852-->A); only the A6-->T transversion resulted in an amino acid substitution (Arg to Ser), which is at the second residue in the 358 amino acid ACMV Rep protein. Our results indicate that a single amino acid can alter the differential ability of ACMV Rep to trigger the host-mediated HR defence mechanism and to initiate viral DNA replication. The implications of this finding are discussed in the context of plant-virus interactions.
Jin
Mingfei
M
School of Life Science, East China Normal University, Shanghai 200062, PR China.|Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK.
Li
Chunyang
C
Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK.
Shi
Yan
Y
Department of Plant Pathology and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.|Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK.
Ryabov
Eugene
E
Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK.
Huang
Jing
J
School of Life Science, East China Normal University, Shanghai 200062, PR China.
Wu
Zirong
Z
School of Life Science, East China Normal University, Shanghai 200062, PR China.
Fan
Zaifeng
Z
Department of Plant Pathology and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100094, PR China.|Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK.
Hong
Yiguo
Y
Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK.
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D004261:DNA Replication; D017791:Geminiviridae / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D054884:Host-Pathogen Interactions; D002365:Manihot / Q000821:virology*; D010935:Plant Diseases / Q000276:immunology / Q000821:virology; D018515:Plant Leaves / Q000821:virology; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication
D014764:Viral Proteins