Phage Lambda Receptor Research Articles

Reversible interaction between coliphage lambda and its receptor protein

The receptor for phage lambda, a protein which can be extracted from the outer membrane of Escherichia coli K12, does not inactivate wild type phage λ in vitro, unless chemicals such as chloroform or ethanol are added to the reaction mixture. In the absence of these compounds the receptor undergoes a reversible interaction with the phage. This interaction is strongly dependent upon the ionic content of the medium. Under optimum conditions a value of 5×10−12 m is found for the equilibrium constant Ka. The values calculated for the association and dissociation rate constants suggest that the phage-receptor complex may exist in two interconvertible conformations. In the presence of chloroform or ethanol the reversible interaction is followed by an irreversible reaction leading to inactivation of the phage. Phage inactivation also occurs in the absence of chloroform or ethanol either if the phage carries a host range mutation, or if the receptor is extracted from some wild strains of E. coli other than strain K12. The reversible interaction observed in vitro is belleved to mimic the first step occurring during adsorption of the phage to its host.

Phage lambda receptor chromosomes for DNA fragments made with restriction endonuclease III of Haemophilus influenzae and restriction endonuclease I of Escherichia coli.

Phage λ DNA yields seven fragments on digestion with endo R. Hin dIII. These seven fragments and the 12 fragments resulting from digestion of λ DNA with both endo R. Hin dIII and endo R. Eco RI have been ordered within the map of the λ genome. The positions of the six r. Hin dIII targets have been defined and all of the targets, other than shin dIIIλ6, can be removed by the combination of a known deletion mutation with the substitution of imm 21 for imm λ . shin dIIIλ6, which is close to or within gene Q , can be removed by the substitution of a small region of the λ chromosome with phi 80 DNA. This permits the construction of receptor chromosomes for DNA fragments generated by endo R. Hin dIII. One receptor pahge, which has about 20% of its DNA deleted, can accommodate DNA fragments within the central region of its chromosome. Other receptor chromosomes are described for DNA fragments from endo R. Hin dIII or endo R. Eco RI digests, in which nearly 40% of the λ DNA has been deleted.

Maltose transport in Escherichia coli K-12: involvement of the bacteriophage lambda receptor

Mutants affected in lamB, the structural gene for phage lambda receptor, are unable to utilize maltose when it is present at low concentrations (less than or equal 10 muM). During growth in a chemostat at limiting maltose concentrations, the lamB mutants tested were selected against in the presence of the wild-type strain. Transport studies demonstrate that most lamB mutants have deficient maltose transport capacities at low maltose concentrations. When antibodies against purified phage lambda receptor are added to a wild-type strain, transport of maltose at low concentrations is significantly reduced. These results strongly suggest that the phage lambda receptor molecule is involved in maltose transport.

Role of the receptor for bacteriophage lambda in the functioning of the maltose chemoreceptor of Escherichia coli.

Chemotaxis towards maltose is specifically defective in many strains of Escherichia coli carrying mutations affecting lamB, the gene coding for the outer membrane receptor for bacteriophage lambda. However, with one exception, the most extreme effect of lamB mutants on the maltose response as determined in the capillary assay is a shift to higher sugar concentrations and a reduction in the number of bacteria accumulated to about 25% of the wild-type level. The severity of the taxis defect is strongly correlated with reduced ability of the cells to take up the maltose present at 1 and 10 muM. Evidence presented here and in the accompanying paper indicates that the lambda receptor is involved in the transport of maltose at these concentrations. The effects of lamB mutations on maltose taxis can be explained by postulating that the high-affinity maltose transport system in which the lambda receptor participates transfers maltose from the surrounding medium across the outer membrane and into the periplasmic space. If the maltose chemoreceptor detects sugar present in the periplasmic space, and not molecules external to the outer membrane, then defective transport of low concentrations of maltose into the periplasm would result in the observed apparent reduction in the sensitivity of the maltose receptor. Thus, the lambda receptor protein would participate in maltose chemorecepton only indirectly through its role in maltose transport.

Quantitation of the loss of the bacteriophage lambda receptor protein from the outer membrane of lipopolysaccharide-deficient strains of Escherichia coli

The recpetor for the phage lambda, a protein component of the outer membrane, is present at decreased levels in strains of Escherichia coli that are deficient in lipopolysaccharide. Loss of the protein was quantitated both by an assay of the phage receptor function and by an assay of antiserum-blocking ability to detect inactive protein. The loss of protein was correlated with the loss of sugar residues and phosphage from the core region of the lipopolysaccharide. Implications for the importance of ionic interactions in the stabilization of the outer membrane are discussed.

Occurrence of the bacteriophage lambda receptor in some enterobacteriaceae.

In Escherichia coli K-12, the receptor for phage lambda is an outer membrane protein which inactivates the phage in vitro. Lambda receptor activity was found in extracts from all wild strains of E. coli tested, although most of them fail to support growth of the phage. In some cases this failure is due to a masking of the receptor in vivo, the bacteria being unable to adsorb the phage or to react with antireceptor antibodies. In other cases, adsorption does occur, and the nature of the block in phage growth was not investigated. Most Mal+ strains of Shigella have lambda receptor, whereas most Mal- strains do not have it. Synthesis of the lambda receptor in Shigella is thus presumably controlled by the positive regulator gene of the maltose regulon as is the case in E. coli K-12. Phage lambda adsorbs on many Mal+ strains of Shigella and even yields plaques on some of them, although at a low frequency. No lambda receptor activity could be found in extracts of several strains of Salmonella and Levinea.

Intergration of the receptor for bacteriophage lambda in the outer membrane of Escherichia coli: coupling with cell division

Induction of the synthesis of the receptor for phage lambda is obtained by adding maltose and adenosine 3'-5'-cyclic monophosphate to glucose grown cells of Escherichia coli. Bacteria induced for a short period of time were infected with a high multiplicity of phage lambda , and examined under the electron microscope. Only a fraction of the bacteria were seen to have adsorbed a large number of phage particles. The majority of such bacteria had a constriction indicating formation of a septum, and, in this case, the density of adsorbed particles was highest in the vicinity of the constriction. When found on bacteria showing no sign of septum formation, the adsorbed particles were asymmetrically distributed, one pole of the bacteria being more heavily covered with phage particles than the other. Such asymetrically covered bacteria are believed to have originated from cells which divided during the induction period. The results suggest that the receptor for phage lambda, a protein of the outer membrane, is integrated in the cell envelope during the last quarter of each generation and that the integration process is initiated in the vicinity of the forming septum.

Requirement of adenosine 3',5'-cyclic phosphate for formation of the phage lambda receptor in Escherichia coli.

Adenosine 3',5'-cyclic phosphate is indispensable for formation of the phage lambda receptor in Escherichia coli K-12.