Nicking and joining activity of banana bunchy top virus replication protein in vitro.

Abstract

The major open reading frame of banana bunchy top virus (BBTV) DNA-1 encodes a putative replication initiation protein (Rep). In vitro, a fusion protein of BBTV Rep linked to a maltose-binding protein exhibited both site-specific nicking and joining activities. These activities were dependent on the presence of Mg 2M or Mn 2M , but did not require ATP. The fusion protein specifically cleaved ssDNA between bases M 7 and M 8 of a conserved nonanucleotide loop sequence which is present in the virion-strand of the stem-loop common region of each BBTV component. During this reaction, the fusion protein became covalently attached to the 5h end of the 3h cleavage product. After the nicking reactions, the fusion protein was also capable of catalysing the joining of two nicked ssDNA fragments in a site-specific manner. Based on these activities, BBTV Rep would appear to be very similar to the Rep proteins of the geminiviruses.

Molecular characterization of banana bunchy top virus isolate from Sri Lanka and its genetic relationship with other isolates

“…The CR-SL is involved in the regulation of replication of components [19]. The second region is CR-M which is the binding site for ssDNA primers reportedly prime the synthesis of transcriptionally active dsDNA [20]. The CR-SL consisted with the conserved stem-loop structure and the loop sequence of 11 nt were conserved in all BBTV components.…”

“…These DNAs encode a single open reading frame (ORF) in virion sense except DNA-R, which has an additional small internal ORF the function of which is not known. Each DNA component has a conserved major common region (CR-M), a stem-loop common region (CR-SL), a potential TATA box and a polyadenylation signal associated with each ORF [5,20].…”

Banana bunchy top disease (BBTD) symptom expression in banana and strategies for transgenic resistance: A review

“…The 69 bp SL-CR shares 62% homology between all six genomic components (Burns et al, 1995), and contains a stem-loop (SL) structure which contains the nanonucleotide loop sequence (5' TATTATTAC 3') was conserved between all components (Burns et al, 1995;Hafner et al, 1997b) and iterative elements (iterons) that are potential Rep binding sites (Horser, 2000a). The CR-M varies in size from between 62 and 92 bp and shares at least 76% homology between all six genomic components (Burns et al, 1995).…”

“…DNA-R encodes the master replication initiation protein (Rep) which is essential for trans-replication of the BBTV genomic components (Horser et al, 2001 a) through its nicking and joining activity (Hafner et al, 1997b). DNA-S encodes the coat protein (CP) (Wanitchakorn et al, 1997), while DNA-M and DNA-N are believed to encode the movement protein (MP) and nuclear shuttle proteins (NSP), respectively (Wanitchakorn et al, 2000).…”

Aspectos patológicos, imunológicos e propriedades moleculares do TT vírus

“…(3) de glicosilação semelhante à asparagina nos diferentes isolados, afetando as propriedades biológicas da proteína resultante, como, por exemplo, a especificidade antigênica (13) . Além dessas características, os produtos de ORF1 do TTV contêm seqüências curtas de aminoácidos características das proteínas associadas a replicação (10) .…”