Rj. Kokoska et Da. Steege, APPROPRIATE EXPRESSION OF FILAMENTOUS PHAGE F1 DNA-REPLICATION GENE-II AND GENE-X REQUIRES RNASE E-DEPENDENT PROCESSING AND SEPARATE MESSENGER-RNAS, Journal of bacteriology, 180(12), 1998, pp. 3245-3249
The products of in-frame overlapping genes II and X carried by the fil
amentous phage fl genome are proteins with required but opposing funct
ions in phage DNA replication, Their normal relative levels are import
ant for continuous production of phage DNA without killing infected Es
cherichia coli hosts, Here we identify several factors responsible for
determining the relative levels of pII and pX and that, if perturbed,
alter the normal distribution of phage DNA species in infected hosts.
Translation of the two proteins is essentially relegated to separate
mRNAs, The mRNAs encoding genes II and X are also differentially sensi
tive to cleavage dependent on rne, the gene encoding the only E. coli
endo-RNase known to have a global role in mRNA stability. Whereas pII
levels are limited at the level of mRNA stability, normal pX levels re
quire transcription in sufficient amounts from the promoter for the sm
aller mRNA encoding only pX.