The Rex system of bacteriophage lambda: tolerance and altruistic cell death.
The rexA and rexB genes of bacteriophage lambda encode a two-component system that aborts lytic growth of bacterial viruses. Rex exclusion is characterized by termination of macromolecular synthesis, loss of active transport, the hydrolysis of ATP, and cell death. By analogy to colicins E1 and K, these results can be explained by depolarization of the cytoplasmic membrane. We have fractionated cells to determine the intracellular location of the RexB protein and made RexB-alkaline phosphatase fusions to analyze its membrane topology. The RexB protein appears to be a polytopic transmembrane protein. We suggest that RexB proteins form ion channels that, in response to lytic growth of bacteriophages, depolarize the cytoplasmic membrane. The Rex system requires a mechanism to prevent lambda itself from being excluded during lytic growth. We have determined that overexpression of RexB in lambda lysogens prevents the exclusion of both T4 rII mutants and lambda ren mutants. We suspect that overexpression of RexB is the basis for preventing self-exclusion following the induction of a lambda lysogen and that RexB overexpression is accomplished through transcriptional regulation.
Department of Molecular, Cellular, and Development Biology, University of Colorado, Boulder 80309-0347.
D H
DH
Parma
M
M
Snyder
S
S
Sobolevski
M
M
Nawroz
E
E
Brody
L
L
Gold
D000255:Adenosine Triphosphate / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000235:genetics* / Q000254:growth & development; D001483:Base Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression; D005814:Genes, Viral; D016355:Genes, pX; D005822:Genetic Vectors; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007473:Ion Channels / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
D007473:Ion Channels; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; C069331:rexB protein, Bacteriophage lambda; D000255:Adenosine Triphosphate; D000469:Alkaline Phosphatase