TY - JOUR
T1 - A 29-mer site regulates transcription of the initiator gene as well as function of the replication origin of Vibrio cholerae chromosome II
AU - Venkova-Canova, Tatiana
AU - Saha, Anik
AU - Chattoraj, Dhruba K.
N1 - Funding Information:
We thank Arnab Sarkar and Souvanik Adhya, for plasmid construction. We are grateful to Michael Yarmolinsky for a critical review of an earlier draft of this paper. This work was supported by the Intramural Research Program, Center for Cancer Research, National Cancer Institute.
PY - 2012/3
Y1 - 2012/3
N2 - The region responsible for replication of . Vibrio cholerae chromosome II (chrII) resembles those of plasmids that have repeated initiator binding sites (iterons) and an autorepressed initiator gene. ChrII has additional features: Its iterons require full methylation for initiator (RctB) binding, which makes them inactive for a part of the cell cycle when they are hemi-methylated. RctB also binds to a second kind of site, called 39-mers, in a methylation independent manner. This binding is inhibitory to chrII replication. The site that RctB uses for autorepression has not been identified. Here we show that a 29-mer sequence, similar to the 39-mers, serves as that site, as we find that it binds RctB in vitro and suffices to repress the . rctB promoter in vivo. The site is not subject to methylation and is likely to be active throughout the cell cycle. The 29-mer, like the 39-mers, could inhibit RctB-dependent mini-chrII replication in . Escherichia coli, possibly by coupling with iterons via RctB bridges, as was seen in vitro. The 29-mer thus appears to play a dual role in regulating chrII replication: one independent of the cell cycle, the other dependent upon iteron methylation, hence responsive to the cell cycle.
AB - The region responsible for replication of . Vibrio cholerae chromosome II (chrII) resembles those of plasmids that have repeated initiator binding sites (iterons) and an autorepressed initiator gene. ChrII has additional features: Its iterons require full methylation for initiator (RctB) binding, which makes them inactive for a part of the cell cycle when they are hemi-methylated. RctB also binds to a second kind of site, called 39-mers, in a methylation independent manner. This binding is inhibitory to chrII replication. The site that RctB uses for autorepression has not been identified. Here we show that a 29-mer sequence, similar to the 39-mers, serves as that site, as we find that it binds RctB in vitro and suffices to repress the . rctB promoter in vivo. The site is not subject to methylation and is likely to be active throughout the cell cycle. The 29-mer, like the 39-mers, could inhibit RctB-dependent mini-chrII replication in . Escherichia coli, possibly by coupling with iterons via RctB bridges, as was seen in vitro. The 29-mer thus appears to play a dual role in regulating chrII replication: one independent of the cell cycle, the other dependent upon iteron methylation, hence responsive to the cell cycle.
KW - Hetero-handcuffing
KW - Operator site
KW - Replication control
KW - Secondary chromosome
KW - Transcriptional autorepression
KW - Vibrio cholerae
UR - http://www.scopus.com/inward/record.url?scp=84859001087&partnerID=8YFLogxK
U2 - 10.1016/j.plasmid.2011.12.009
DO - 10.1016/j.plasmid.2011.12.009
M3 - Article
C2 - 22248922
AN - SCOPUS:84859001087
SN - 0147-619X
VL - 67
SP - 102
EP - 110
JO - Plasmid
JF - Plasmid
IS - 2
ER -