TY - JOUR
T1 - Molecular characterization of the Rep protein of the blackgram isolate of Indian mungbean yellow mosaic virus
AU - Pant, V.
AU - Gupta, D.
AU - Choudhury, N. R.
AU - Malathi, V. G.
AU - Varma, A.
AU - Mukherjee, S. K.
PY - 2001
Y1 - 2001
N2 - The complete nucleotide sequence of the blackgram isolate of mungbean yellow mosaic virus, IMYMV-Bg, which infects legumes in India, was determined and compared at the amino acid level with those of other whitefly-transmitted geminiviruses. The genome organization of IMYMV-Bg was similar to that of the begomoviruses. A unique feature of the genome organization was the sequence divergence of the common region (CR) between DNA-A and DNA-B. In order to understand the mechanism of viral DNA replication, the replication initiator protein, Rep, of IMYMV-Bg was overexpressed in E. coli. The recombinant and refolded Rep bound to CR-sequences of IMYMV-Bg in a specific manner. In this study, evidence is presented for ATP-upregulated cleavage function and ATP-mediated conformational change of Rep. It is hypothesized that, although ATP is not required for cleavage, ATP-mediated conformational changes may result in better access of Rep to the DNA-cleavage site. Evidence is also presented for a site-specific topoisomerase function of Rep, which has not been demonstrated before. The Rep protein can be classified as a type-1 topoisomerase because of its nicking activity and sensitivity towards camptothecin, a topoisomerase type-I inhibitor.
AB - The complete nucleotide sequence of the blackgram isolate of mungbean yellow mosaic virus, IMYMV-Bg, which infects legumes in India, was determined and compared at the amino acid level with those of other whitefly-transmitted geminiviruses. The genome organization of IMYMV-Bg was similar to that of the begomoviruses. A unique feature of the genome organization was the sequence divergence of the common region (CR) between DNA-A and DNA-B. In order to understand the mechanism of viral DNA replication, the replication initiator protein, Rep, of IMYMV-Bg was overexpressed in E. coli. The recombinant and refolded Rep bound to CR-sequences of IMYMV-Bg in a specific manner. In this study, evidence is presented for ATP-upregulated cleavage function and ATP-mediated conformational change of Rep. It is hypothesized that, although ATP is not required for cleavage, ATP-mediated conformational changes may result in better access of Rep to the DNA-cleavage site. Evidence is also presented for a site-specific topoisomerase function of Rep, which has not been demonstrated before. The Rep protein can be classified as a type-1 topoisomerase because of its nicking activity and sensitivity towards camptothecin, a topoisomerase type-I inhibitor.
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U2 - 10.1099/0022-1317-82-10-2559
DO - 10.1099/0022-1317-82-10-2559
M3 - Article
C2 - 11562548
AN - SCOPUS:0034795504
SN - 0022-1317
VL - 82
SP - 2559
EP - 2567
JO - Journal of General Virology
JF - Journal of General Virology
IS - 10
ER -