Promoters, transcripts, and regulatory proteins of Mungbean yellow mosaic geminivirus.
Geminiviruses package circular single-stranded DNA and replicate in the nucleus via a double-stranded intermediate. This intermediate also serves as a template for bidirectional transcription by polymerase II. Here, we map promoters and transcripts and characterize regulatory proteins of Mungbean yellow mosaic virus-Vigna (MYMV), a bipartite geminivirus in the genus Begomovirus. The following new features, which might also apply to other begomoviruses, were revealed in MYMV. The leftward and rightward promoters on DNA-B share the transcription activator AC2-responsive region, which does not overlap the common region that is nearly identical in the two DNA components. The transcription unit for BC1 (movement protein) includes a conserved, leader-based intron. Besides negative-feedback regulation of its own leftward promoter on DNA-A, the replication protein AC1, in cooperation with AC2, synergistically transactivates the rightward promoter, which drives a dicistronic transcription unit for the coat protein AV1. AC2 and the replication enhancer AC3 are expressed from one dicistronic transcript driven by a strong promoter mapped within the upstream AC1 gene. Early and constitutive expression of AC2 is consistent with its essential dual function as an activator of viral transcription and a suppressor of silencing.
Shivaprasad
P V
PV
Institute of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland.
Akbergenov
Rashid
R
Trinks
Daniela
D
Rajeswaran
R
R
Veluthambi
K
K
Hohn
Thomas
T
Pooggin
Mikhail M
MM
D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004270:DNA, Circular / Q000235:genetics; D004277:DNA, Single-Stranded / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D017791:Geminiviridae / Q000235:genetics*; D016679:Genome, Viral; D008969:Molecular Sequence Data; D027805:Phaseolus / Q000821:virology; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*
D017931:DNA Primers; D004270:DNA, Circular; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D014764:Viral Proteins