CNR PROTEIN, THE NEGATIVE REGULATOR OF BACTERIOPHAGE-P4 REPLICATION, STIMULATES SPECIFIC DNA-BINDING OF ITS INITIATOR PROTEIN-ALPHA

Citation
G. Ziegelin et al., CNR PROTEIN, THE NEGATIVE REGULATOR OF BACTERIOPHAGE-P4 REPLICATION, STIMULATES SPECIFIC DNA-BINDING OF ITS INITIATOR PROTEIN-ALPHA, Journal of bacteriology, 179(9), 1997, pp. 2817-2822
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
ISSN journal
0021-9193
Volume
179
Issue
9
Year of publication
1997
Pages
2817 - 2822
Database
ISI
SICI code
0021-9193(1997)179:9<2817:CPTNRO>2.0.ZU;2-C
Abstract
Bacteriophage P4 DNA replication depends upon the phage-encoded alpha protein, which has DNA helicase and DNA primase activity and can speci fically bind to the replication origin (ori) and to the cis replicatin g region (crr). The P4 Cnr protein functions as a negative regulator o f P4 replication, and P4 does not replicate in cells that overexpress cnr. We searched for P4 mutants that suppressed this phenotype (Cnr re sistant [alpha cr]). Eight independent mutants that grew in the presen ce of high levels of Cnr were obtained, None of these can establish th e plasmid state, Each of these mutations lies in the DNA binding domai n of gp alpha that occupies the C terminus of the protein, Five differ ent sequence changes were found: T675M, G732V (three times), G732W (tw ice), L733V, and L737V, A TrxA-Cnr fusion protein does not bind DNA by itself but stimulates the ori and crr binding abilities of alpha prot ein in vitro. The alpha cr mutant proteins were still able to bind spe cifically to ori or crr, but specific DNA binding was less stimulated by the TrxA-Cnr protein, We present evidence that Cnr protein interact s with the gp alpha domain that binds specifically to DNA and that gp alpha cr mutations impair this interaction, We hypothesize that gp alp ha-Cnr interaction is essential for the control of P4 DNA replication.