Tao, Jing-Song2024-08-152024-08-1519891989https://hdl.handle.net/1828/19859Two approaches were used to study the murE gene encoding the diaminopimelic acid adding enzyme of Escherichia coli. In the first approach, the cloning and nucleotide sequencing of the murE gene has been performed. The coding region of murE consisted of 1,413 base pairs. The open reading frame of murE gene was separated from the ftsl ( penicillin-binding protein 3 ) gene by 61 base pairs, and it overlapped the initiation codon of the murF ( D-Ala-D-Ala adding enzyme) gene by one base pair. The deduced primary structure of MurE comprised 41 7 amino acid residues with a molecular mass of 50.6 kilodaltons. Amino acid sequences corresponding to the domains A and B of proposed ATP binding sites were identified in the deduced amino acid sequence of MurE. The close linkage of the murE gene to its upstream and downstream neighbouring genes was similar to the close linkage of the other genes in 2-min region of E. coli genetic linkage map. The interesting physical arrangement of the genes in this region and the fact that they are all involved in cell envelope metabolism or cell division has prompted the speculation of some novel form of regulation. As a second approach, extragenic suppressor mutations, which suppress the temperature- sensitive lysis phenotype of the murE16 allele, have been isolated and preliminarily characterized. Growth studies indicated that the murE16 mutation was at least partially osmoremedial, Further more, the two suppressor mutations characterized in this study functioned as suppressors of murE16 only in high osmolarity medium. The attempt to map the suppressor mutations were unsuccessful, and the products of the suppressor genes have not been identified.73 pagesAvailable to the World Wide WebThesis