In the course of our work on the biochemistry of receptor-active components of the Escherichia coli B cell wall, bacteriophages quite generally proved to be very useful and sensitive tools for helping to dissect the wall into many different, functionally intact, macro-components. For this discussion the most relevant result of these dissections is the finding that the coli wall is composed of two layers: one is lipoprotein and amounts to about 80 yo of the dry weight of the cell wall; the other layer is characterized by a large content of saccharides + lipids + a few typical amino acids which later will be considered more closely. This 2 0 % layer we have called the lipopolysaccharide layer (Weidel, Koch & Lohss, 1954).After removing the lipoprotein layer from isolated cell walls by 90 % phenol, in which it is soluble, the remaining lipopolysaccharide, when viewed under the phase-contrast microscope, appears largely in the form of extremely thinwalled transparent rods. Obviously the lipopolysaccharide layer is rod-shaped as such and forms the supporting framework of the coli wall to which it lends rigidity. The lipoprotein cannot have either of these two properties by itself because of its great plasticity which becom-directly noticeable after removing by dialysis the phenol in which it was dissolved.The relative positions of these two layers can be ascertained by using phages as indicators. Before phenol treatment the coli wall adsorbs the coliphages T2, T4 and T6. After removing the lipoprotein layer with phenol, T2 and T6 are no more adsorbed by the remainder of the wall, i.e. the lipopolysaccharide, whereas the adsorbability of T 4, as measured by rate of adsorption, is markedly increased. One is led to the conclusion that additional receptor sites for T4, which all lie in the polysaccharide layer, must have been uncovered and made accessible by removing the lipoprotein. Since the phage particles in these tests can interact with the wall from the outside only, it would follow that the outside is formed largely by the lipoprotein layer which contains the receptor sites for T2 and T6 and covers a great deal of the T4-sites actually present in the lipopolysaccharide layer.With this picture in mind we now turn to the mechanism of destruction of the double-layered coli wall by certain virulent phages. As early as 1949 we were able to show on electron micrographs that coliphage T 2, after adsorption to coli cell walls, causes structural changes within, and release of material from them (Weidel, 1951). This phenomenon seemed to indicate a specific enzymic activity of the phage particle which might well explain the more general phenomena of virus penetration and lysis 'from within' or 'from without '.
Nr. 4119431 S c li r a m m , P r i m o s i g h. 373gelangen kann. Unter tliesen trmstainden ist die beobachtete Wirkungskonstante natiirlich recht klein uncl betragt der GroBenordnuxig nach:Bei Zuxiahme der Katalysatorkonzentration wird auch in diesem Falle zuuachst eine Zunahme und dann eine rasche Abnahme der maximalen Helligkeit der Luminescenz beobachtet, also ist auch dieser EinfluB qualitativ genau so wie bei der Verwendung der anderen Katalysatoren. Die hier benutzte Versuchsmethode wurde schon in den friiheren Mitteilungen beschrieben. Die Luniinolkonzentration hetrug bei allen Versucheii dieser Arbeit 8 x lo-* Mol/Z. Die Versuche iiber die Inhibitorwirkung wurdeii iinmer bei den optinialen Animoniak-und Katalysatorkonzentrationen vorgenommen. Als maximale Helligkeit der Lumitiescenz -,in relativen Einheitenbezeichnen wir den grogten beobachteten Ausschlag des Galvanometers beini betreffenden Versuch ; dieser kouute gewohnlich unmittelbar nach dem ZusammengieBen der Reaktionsgeniische abgelesen werden. Alu Anfangshelligkeit, die zum Vergleich mit den friiheren Versuchen diente, nurde die Helligkeit nach 20 Sek. Reaktionszeitwieder relativ in Galvanonieteraussclilageiigenonimexi. -Die bexiutzten Katalysatoren waren einfache Kahlbaum-Praparate. Die Liisungen des RuCI, muf3ten ofter frisch bereitet werden, da gealterte Losungen, die hydrolytischen Veranderiingen unterliegen, eine wesentlich geringere katalytische Wirkung zeigten.Hrn. Prof. Dr. J. P l o t n i k o n -danken wir fiir die Lnterstiitzung diescr Xrbtit niit Jfittelxi des Instituts.
One of the two layers of the E. coli B cell wall is shown to possess the chemical composition typical of a gram-positive microorganism. It is this layer which lends support and strength to the entire cell wall structure, its rigidity depending up on the incorporation of building blocks made up from alanine, glutamic acid, diaminopimelic acid, muramic acid and glucosamine.Phage enzyme is an agent capable of removing these stabilizing units from the "gram-positive" layer, thereby causing it to collapse. Penicillin appears to prevent the biosynthetic incorporation of the same stabilizing units into growing cell walls, thus producing eventually the effect of cell wall disruption in a basically similar way.The rather manifold aspects of these findings are discussed at some length.
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