Affiliation:
1. Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010, Australia
Abstract
ABSTRACT
Replication of the IncB miniplasmid pMU720 requires synthesis of the replication initiator protein, RepA, whose translation is coupled to that of a leader peptide, RepB. The unusual feature of this system is that translational coupling in
repBA
has to be activated by the formation of a pseudoknot immediately upstream of the
repA
Shine-Dalgarno sequence. A small antisense RNA, RNAI, controls replication of pMU720 by interacting with
repBA
mRNA to inhibit expression of
repA
both directly, by preventing formation of the pseudoknot, and indirectly, by inhibiting translation of
repB
. The mechanism of translational coupling in
repBA
was investigated using the specialized ribosome system, which directs a subpopulation of ribosomes that carry an altered anti-Shine-Dalgarno sequence to translate mRNA molecules whose Shine-Dalgarno sequences have been altered to be complementary to the mutant anti-Shine-Dalgarno sequence. Our data indicate that translation of
repA
involves reinitiation by the ribosome that has terminated translation of
repB
. The role of the pseudoknot in this process and its effect on the control of copy number in pMU720 are discussed.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
13 articles.
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