Active Transport of Glucose-1-Phosphate in Agrobacterium tumefaciens

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RESUMO

The presence of an active transport system for glucose-1-phosphate in Agrobacterium tumefaciens was demonstrated from the following observations. (i) The bacterium could grow on a medium containing glucose-1-phosphate as carbon source; (ii) the entry of glucose-1-phosphate into the resting cells occurred against concentration gradient obeying Michaelis-Menten kinetics; and (iii) the entry reaction was energy-dependent. The transport system for glucose-1-phosphate was formed inducibly by growing the organism on a glucose-1-phosphate or sucrose medium. From the inhibition and kinetics studies it was found that the transport system had a high specificity for glucose-1-phosphate with a high affinity, Km value of 4.5 × 10−6m at pH 8.2. The existence of glucose-1-phosphate binding factor was proved in the shock fluid which was prepared from the cells grown on both glucose-1-phosphate and sucrose media by osmotic shock.

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