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Two classes of membrane binding of replicative RNA of bacteriophage MS2
Abstract:
Escherichia coli membranes were isolated in the presence of 6 mM Mg(++). They were washed with buffer containing no Mg(++) to yield a fraction containing material bound only in the presence of divalent cations, "membrane eluate," and that bound in the absence of divalent cations, "membrane." When E. coli infected with bacteriophage MS2 are labeled with [(14)C]uracil, all MS2 replicative RNA, i.e., the RNA species containing MS2 complementary RNA, is in the membrane eluate and membrane. The amount of [(14)C]uracil in replicative RNA found in the membrane eluate increases with time of labeling, whereas that in the replicative RNA in the membrane reaches a plateau in 1-2 min. This finding is consistent with a precursor-product relationship. Most of the label entering single-stranded viral RNA comes from the replicative RNA in the membrane eluate. This result suggests that polymerase components or factors required for complementary-strand synthesis are bound to membrane even in the absence of divalent cations and that the polymerase is no longer bound to these factors when it is making the bulk of the progeny single-stranded RNA.
Insights
Bacteriophage MS2 replication involves membrane-bound factors essential for RNA synthesis. These factors are released during progeny RNA production, suggesting a dynamic polymerase-membrane interaction.
Area of Science:
- Molecular Biology
- Virology
- Bacterial Physiology
Background:
- Escherichia coli membranes play a role in bacteriophage replication.
- Bacteriophage MS2 RNA synthesis requires specific cellular components.
Purpose of the Study:
- To investigate the role of Escherichia coli membranes in bacteriophage MS2 RNA replication.
- To elucidate the dynamics of viral RNA synthesis and polymerase binding.
Main Methods:
- Isolation of E. coli membranes under varying Mg(++) conditions.
- Labeling of bacteriophage MS2-infected E. coli with [(14)C]uracil.
- Fractionation of membrane-associated and eluted RNA components.
Main Results:
- MS2 replicative RNA is localized to both membrane and eluate fractions.
- Replicative RNA in the eluate increases with labeling time, while membrane-bound RNA plateaus.
- Viral RNA synthesis involves a precursor-product relationship and dynamic polymerase-membrane interactions.
Conclusions:
- Polymerase components for complementary-strand synthesis bind to membranes even without Mg(++).
- The polymerase detaches from these factors during progeny single-stranded RNA production.
- Membrane-bound factors are crucial for initiating and regulating MS2 RNA replication.