Two - Component Nature of Bacteriophage T 4 Receptor Activity in Escherichia coli K - 12 ULF HENNING ' * AND KLAUS JANN

    Abstract

    It has been established (22) and studied in more detail (6, 14) that Escherichia coli phage T4 uses the lipopolysaccharide (LPS) of the outer cell envelope membrane as receptor. However, selection for resistance to phage T4 can yield mutants missing one of the so-called major outer membrane proteins, polypeptide Ib (19). We have investigated this observation further, and here we present evidence that, in contrast to LPS from E. coli B/r, LPS from E. coli K-12 requires protein lb to exhibit phage receptor activity. In most E. coli K-12 strains the major outer membrane protein of interest consists of two very similar polypeptides, Ia and lb (19; they are identical with la/lb [1], b/c [10], 0-9/0-8 [13], A1/A2 [17], 4 [20], and one of the two with the matrix protein [18]). In E. coli B/r only one such protein is present, and, as judged from its electrophoretic mobility and phage resistance pattern (see Table 1), it is polypeptide Ia. We have isolated two phages, Tula and Tulb, which use proteins Ia and lb, respectively (3), as parts of their receptors. Selection for resistance against these phage yields mutants frequently deficient in the corresponding protein. Table 1 shows phage resistance patterns of various strains differing in the protein I species they synthesize. Resistance or sensitivity to phages Tula and TuIb is paralleled by either the absence or presence of the corresponding protein. All E. coli K-12 strains missing protein lb, however, are resistant to phage T4, whereas E. coli B/r also missing this protein is sensitive. The receptor for T4 is LPS, and the nature of the mutations causing loss of protein Ib is not known. We had previously considered the possibility that K-12 mutants missing protein Ib may be mutants primarily affecting the LPS. LPS isolated (7) from E. coli B/r, K-12 P400, and K-12 P400 TuIbr6 were therefore tested for activity against T4 (Table 2). The data show that B/r LPS effectively inactivated the phage, whereas both K-12 LPS were completely inactive. For comparative chemical analyses, these LPS were degraded in 1% acetic acid to yield the corresponding core oligosaccharides, which were purified by gel chromatography as described previously (14). The two K-12 core oligosaccharides had almost the same composition (Table 3). Their galactose-glucose-heptose ratio was about 1:3:4. The B/r core oligosaccharide, which had a glucose-heptose ratio approximating 2:3, did not contain galactose. These values are in good agreement with previously published data (14, 15). These results suggested an interaction between LPS and protein Ib, the latter perhaps enabling LPS to act as T4 receptor. Isolation of proteins Ia and Ib involves boiling in sodium dodecyl sulfate (9), and this step completely and, as far as we have tried, irreversibly inactivates them as receptors for phages TuIa and TuIb. These polypeptides are tightly associated with the cell envelope's murein layer, and a complex can be prepared consisting essentially of the various protein I species plus murein (18). Such protein I complexes remain active as phage receptors. Incomplete removal of residual LPS from such complexes is a disadvantage. Methods exist to remove proteins I as aggregates from murein without denaturation of the receptor activity for phages TuIa or TuIb (12, 13). However, these preparations were also contaminated with LPS, and we have therefore simply used Rosenbusch's murein-protein I complexes (18). The data presented in Table 2 show that only complexes containing protein lb enabled K-12 LPS to inactivate phage T4 regardless of the origin of LPS (Ia+Ib+ or Ia+Ibstrain). The results can be interpreted by comparing the structures of the respective LPS. In E. coli B the core oligosaccharide terminates in the

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    @inproceedings{TwoC, title={Two - Component Nature of Bacteriophage T 4 Receptor Activity in Escherichia coli K - 12 ULF HENNING ' * AND KLAUS JANN}, author={} }