Alteration of ribosomal protein S4 by mutation linked to kasugamycin-resistance in Escherichia coli

An alteration in the chromatographic mobility of 30S ribosomal protein S4 from two kasugamycin-resistant (ksgA) strains of E. coli was observed. The locus determining this alteration frequently cotransduced with ksgA but could be separated from it by transduction and conjugation. Since the structural gene for protein S4 is thought to lie some 30 min from ksgA on the E. coli chromosome, the product of the newly-identified gene may modify protein S4. We propose to designate this gene ramB.Reconstitution of 30S subunits from RNA and protein components of ksgA ramB and ksgA(+)ramB(+) strains demonstrated that ribosomal resistance to kasugamycin was due to altered 16S RNA and not to altered protein S4. The altered 16S RNA was undermethylated, and a methylating enzyme that acts on 16S RNA from ksgA strains was present in ksgA(+) but not in ksgA strains.

N-acetylmuramyl-L-alanine amidase of Bacillus licheniformis and its L-form

A cell wall lytic enzyme has been demonstrated to be a component of the membrane of Bacillus licheniformis NCTC 6346 and an l-form derived from it. The lytic enzyme, characterized as an N-acetylmuramyl-l-alanine amidase, is solubilized from membranes by nonionic detergents. Ionic detergents inactivate the enzyme. In the bacterium the specific activities of amidase and d-alanine carboxypeptidase in mesosomes are approximately 65% of those in membranes. Selective transfer of lytic enzyme from nongrowing L-forms, L-form membranes, and protoplasts to added walls occurred after mixing, and 31 to 77% of the enzyme lost from L-form membranes was recovered on the walls. Membranes isolated from L-forms growing in the presence of added walls contained as little as 13% of the amidase found in membranes of a control culture. These results have been interpreted as showing that in vivo the amidase is "bound" to the surface of the bacterial cell membrane in such a location that it can be readily accessible to the cell wall.