The proteins encoded by the rbs operon of escherichia coli: I. Overproduction, purification, characterization, and functional analysis of RbsA

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Abstract
The nucleotide-binding component of the high-affinity ribose transport system of Escherichia coli, RbsA, was overproduced from a T7–7 expression vector, and the protein was purified. Biochemical analyses of the purified protein indicated that the ATP analogues, 5′-FSBA and 8-azido ATP, covalently labeled the protein, a reaction that was inhibited by ATP, but not by GTP or CTP. The pure protein exhibited low-level ATPase activity with a Km of about 140 μM. Analyses of bacterial strains carrying chromosomal deletions of rbsA and other rbs genes suggested that RbsA is important for the chemotaxis function, a surprising result that was not anticipated from previous studies. However, an inconsistency between the several results from deletion strains raises questions regarding the interpretations of the in vivo data.