Open AccessThe Major Proteins of the Escherichia coli Outer Cell Envelope Membrane
Author(s) -
GARTEN Wolfgang,
HINDENNACH Ingrid,
HENNING Ulf
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb02444.x
Subject(s) - bacterial outer membrane , escherichia coli , cell envelope , membrane protein , biochemistry , protein a/g , chemistry , vesicle associated membrane protein 8 , protein g , biology , integral membrane protein , membrane , recombinant dna , fusion protein , gene , antibody , genetics
Protein II*, one of the major Escherichia coli outer cell envelope membrane proteins has been characterized. The protein is heat‐modifiable and perhaps due to complete unfolding and/or binding of sodium dodecylsulfate only at higher temperatures the modified protein exhibits a higher apparent molecular weight (33000) than the non‐modified form (28000). Protein‐chemical evidence as well as the behavior of two mutant proteins II* very strongly suggest that this protein consists of a single polypeptide chain and that in the strains studied there is no other major protein with similar characteristics. For another outer membrane protein, protein III (molecular weight 17000), it has not yet been established if it should be classified as a major protein. Protein III consists of one or perhaps two polypeptide chains. The possibility existed that protein III is bound covalently to lipopolysaccharide, and this has been ruled out. Also, the lipopolysaccharide of the E. coli strains studied does not carry covalently bound protein in amounts anywhere near stoichiometry. Non‐protein substituents were neither found in protein II* nor in protein III. It is concluded that in E. coli B/r and the E. coli K 12 strains used there are three major proteins: I, II*, and IV; protein III may also belong to this class. There are not more major proteins than these. All four proteins are compared and discussed regarding their unknown functions and their relation to E. coli outer membrane proteins studied by other authors.