STRUCTURE OF THE RIBOSE OPERON OF ESCHERICHIA COLI K12
Abstract
The ribose operon of E.coli K12 consists of at least three genes involved in ribose transport, rbsA, rbsC, and rbsB, in that order. rbsB encodes the periplasmic ribose binding protein (RBP). rbsA and rbsC very likely encode proteins of the inner membrane, and along with RBP may constitute the entire high-affinity transport system for ribose. rbsK is the structural gene for ribokinase (E.C.2.7.1.15) and lies downstream from the transport genes. The complete nucleotide sequence and corresponding amino acid sequence of RBP and one of the inner membrane proteins (rbsC) have been determined. The N-terminal sequence of ribokinase has been determined by a combination of protein and nucleotide sequence analyses. RBP shows considerable homology to the galactose binding protein (GBP). These homologous areas appear in clusters in the sequence and are located on the surface of the molecules near the sugar binding site. Since RBP and GBP utilize different inner membrane transport proteins but interact with the same chemotaxis transducer, MCPIII, the homologous areas may well represent the areas of the RBP and GBP molecules important for recognition of MCPIII. The rbsC deduced amino acid sequence is characteristic of inner membrane proteins. Three potential transmembrane segments of the protein have been identified. The rbsC protein has a calculated molecular weight of 26,600. Ribokinase has been purified to near homogeneity (90%) and represents the first purification of a ribokinase from a microorganism.
Degree
Ph.D.
Subject Area
Biochemistry
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