Open AccessDNA Helicase Activity Is Associated with the Replication Initiator Protein Rep of Tomato Yellow Leaf Curl Geminivirus
Author(s) -
Danielle Clérot,
Françoise Bernardi
Publication year - 2006
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.00924-06
Subject(s) - biology , helicase , rna helicase a , control of chromosome duplication , dna replication , viral replication , minichromosome maintenance , dna , virus , genetics , microbiology and biotechnology , virology , rna , gene
The Rep protein of tomato yellow leaf curl Sardinia virus (TYLCSV), a single-stranded DNA virus of plants, is the replication initiator essential for virus replication. TYLCSV Rep has been classified among ATPases associated with various cellular activities (AAA+ ATPases), in superfamily 3 of small DNA and RNA virus replication initiators whose paradigmatic member is simian virus 40 large T antigen. Members of this family are DNA- or RNA-dependent ATPases with helicase activity necessary for viral replication. Another distinctive feature of AAA+ ATPases is their quaternary structure, often composed of hexameric rings. TYLCSV Rep has ATPase activity, but the helicase activity, which is instrumental in further characterization of the mechanism of rolling-circle replication used by geminiviruses, has been a longstanding question. We present results showing that TYLCSV Rep lacking the 121 N-terminal amino acids has helicase activity comparable to that of the other helicases: requirements for a 3' overhang and 3'-to-5' polarity of unwinding, with some distinct features and with a minimal AAA+ ATPase domain. We also show that the helicase activity is dependent on the oligomeric state of the protein.