Geminivirus replication proteins are related to prokaryotic plasmid rolling circle DNA replication initiator proteins

Abstract

It is demonstrated, by means of computer-assisted analysis, that C1 protein involved in the replication of geminivirus DNA is related to the rolling circle replication initiator proteins of eubacterial plasmids, particularly the plasmids of the pMV 158 family. Three sequence motifs conserved in the geminivirus and plasmid replication proteins were delineated, one of them encompassing the Tyr residue that presumably forms a covalent linkage to DNA. These findings are compatible with the results of recent analyses of geminivirus replicative intermediates suggesting a rolling circle mechanism for geminivirus DNA replication. It is hypothesized that C1 protein initiates the rolling circle replication of geminivirus DNA by nicking a specific site in the virus-sense DNA and covalently linking to the 5' side of the nick. The putative rolling circle replication initiator domain comprises the N-terminal portion of C l, whereas its Cterminal part is a putative helicase domain. By analogy with prokaryotic systems, it is speculated that the replication initiator domain and the helicase domain function coordinately. The possibility of the origin of geminiviruses from prokaryotic circular ssDNA replicons is discussed.

Mutational analysis of potato yellow mosaic geminivirus

“…These results are consistent with those found for TGMV, ACMV and AbMV where mutations to the analogous ORFs Etessami et al, 1991 ;Evans & Jeske, 1993b) gave essentially similar results. The ALl proteins are absolutely required for geminivirus DNA replication and their significant homology with the replication-associated proteins of bacteriophage and eubacterial plasmids (Koonin & Ilyina, 1992) suggests that the proteins may possess nicking, helicase and/or ligase activities (Timmermans et al, 1994). The TGMV ALl protein auto-regulates its own transcription (Sunter et al, 1993), binds to TGMV DNA at specific sites and possesses multifunctional enzymatic activity (Fontes et al, 1994).…”

TGMV replication protein AL1 preferentially binds to single‐stranded DNA from the common region

“…Several eukaryotic DNA helicases have been found to bind specifically or preferentially to single-stranded DNA [20]. Geminivirus AL1 proteins also have an N-terminal domain with sequence motifs characteristic of rolling circle replication initiator proteins (RCRs) of bacterial plasmids [21]. The most widely studied RCR, the gene A protein of bacteriophage @X174, has been shown to be a sequence-specific endonuclease.…”

A novel maize-infecting mastrevirus from La Réunion Island

“…Within the MSRV Rep we identified various amino acid motifs previously identified in other mastreviruses including (1) a likely rolling-circle replication (RCR) motif I sequence (FLTYP [11]), (2) a possible metal ion coordination domain (HLHVLLQ, corresponding to RCR motif II [11]), (3) a possible GRS motif (YHPNIQASR [14]), (4) a possible RCR motif III sequence (YILKSP [11]), (5) a probable dNTP-binding domain sequence (VGX 4 GKTTW 30 DD [8]), (6) a retinoblastoma-related protein binding motif (LHCYE [27]), and (7) a potential oligomerisation domain (SAERLFPTLPSPFV [10]; Supplementary Fig. 2).…”