TY - JOUR
T1 - Mutations affecting localization of an Escherichia coli outer membrane protein, the bacteriophage λ receptor
AU - Emr, Scott D.
AU - Silhavy, Thomas J.
N1 - Funding Information:
We thank M. Schwartz, M. Hofnung and H. Shuman for providing strains, S. Benson and M. Pearson for critically reading the manuscript, and P. Fritz for assistance in the typing of the manuscript. This work was supported by a Public Health grant from the National Institute of General Medical Sciences (GM25524) and the Medical Foundation, Boston, Mass. (to T. J. S.) and by the National Cancer Institute under contract no. NO 1-CO-75380 with Litton Bionetics, Inc.
PY - 1980/7/25
Y1 - 1980/7/25
N2 - Mutants have been isolated in which the cellular location of the phage λ receptor protein, an Escherichia coli outer membrane protein, is altered. The mutations were selected for in a strain containing a lamB-lacZ‡ gene fusion. The fused gene codes for a hybrid protein comprised of λ receptor sequences at its aminoterminal end and active β-galactosidase at its carboxy-terminal end. In the parent strain the hybrid protein is localized, at least in part, to the outer membrane of the cell. The mutations described here cause the hybrid protein to be located in the cytoplasm. These mutations (both point mutations and deletions) have been found to lie very early in the lamB gene. When these mutations are incorporated into an otherwise wild-type lamB gene, most also prevent export of λ receptor and cause, instead, the precursor form of the λ receptor protein to accumulate in the cell cytoplasm. It is suggested that this group of mutations leads to alterations in the λ receptor signal sequence and thereby prevents export of this protein. For reasons that are as yet unclear, another group of mutants that prevent export of the hybrid protein does not drastically affect localization of the λ receptor protein. Also described is an unusual deletion mutation that was obtained by a similar selection procedure. This deletion results in the fusion of malK (promoter proximal to lamB) to lamB, which in turn is fused to lacZ. This double fusion codes for a MalK-LamB-LacZ tribrid protein that exhibits both MalK and LacZ activities and is localized almost exclusively to the inner membrane of the cell.
AB - Mutants have been isolated in which the cellular location of the phage λ receptor protein, an Escherichia coli outer membrane protein, is altered. The mutations were selected for in a strain containing a lamB-lacZ‡ gene fusion. The fused gene codes for a hybrid protein comprised of λ receptor sequences at its aminoterminal end and active β-galactosidase at its carboxy-terminal end. In the parent strain the hybrid protein is localized, at least in part, to the outer membrane of the cell. The mutations described here cause the hybrid protein to be located in the cytoplasm. These mutations (both point mutations and deletions) have been found to lie very early in the lamB gene. When these mutations are incorporated into an otherwise wild-type lamB gene, most also prevent export of λ receptor and cause, instead, the precursor form of the λ receptor protein to accumulate in the cell cytoplasm. It is suggested that this group of mutations leads to alterations in the λ receptor signal sequence and thereby prevents export of this protein. For reasons that are as yet unclear, another group of mutants that prevent export of the hybrid protein does not drastically affect localization of the λ receptor protein. Also described is an unusual deletion mutation that was obtained by a similar selection procedure. This deletion results in the fusion of malK (promoter proximal to lamB) to lamB, which in turn is fused to lacZ. This double fusion codes for a MalK-LamB-LacZ tribrid protein that exhibits both MalK and LacZ activities and is localized almost exclusively to the inner membrane of the cell.
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U2 - 10.1016/S0022-2836(80)80029-5
DO - 10.1016/S0022-2836(80)80029-5
M3 - Article
C2 - 6448927
AN - SCOPUS:0019332779
SN - 0022-2836
VL - 141
SP - 63
EP - 90
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 1
ER -