Title: [30] Methods for the study of the melibiose carrier of Escherichia coli
Abstract: This chapter describes methods used for measuring the transport of both the sugar and cation substrates. Some of these methods such as the preparation of radioactive melibiose and the construction of the Li+-selective electrode were devised specifically for studies of the melibiose transport system. The melibiose carrier of Escherichia coli is a representative of the class of carriers that require a cation for cotransport. An unusual feature of this transport system is that it is able to utilize Na +, Li +, or H + as the coupling cation depending on the conditions. Another interesting property of the carrier is that different sugar substrates show different specificities for the cation requirement. A variety of strains of E. coli has been isolated for use in experiments on the melibiose carrier. It is essential to start with a strain from which the lactose carrier (lac Y) has been deleted, as the lac carrier also is capable of transporting melibiose. The growth of normal E. coli cells on melibiose minimal medium is strongly inhibited by 10 mM Li+ and it is therefore possible to isolate Li+-resistant mutants. This organism is dependent on Na+ or Li+ for growth on melibiose as it has lost the ability to transport the disaccharide with protons.
Publication Year: 1986
Publication Date: 1986-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 16
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