Galactose catabolism in Caulobacter crescentus

Caulobacter crescentus wild-type strain CB13 is unable to utilize galactose as the sole carbon source unless derivatives of cyclic AMP are present. Spontaneous mutants have been isolated which are able to grow on galactose in the absence of exogenous cyclic nucleotides. These mutants and the wild-type strain were used to determine the pathway of galactose catabolism in this organism. It is shown here that C. crescentus catabolizes galactose by the Entner-Duodoroff pathway. Galactose is initially converted to galactonate by galactose dehydrogenase and then 2-keto-3-deoxy-6-phosphogalactonate aldolase catalyzes the hydrolysis of 2-keto-3-deoxy-6-phosphogalactonic acid to yield triose phosphate and pyruvate. Two enzymes of galactose catabolism, galactose dehydrogenase and 2-keto-3-deoxy-6-phosphogalactonate aldolase, were shown to be inducible and independently regulated. Furthermore, galactose uptake was observed to be regulated independently of the galactose catabolic enzymes.

[1]  M. Doudoroff,et al.  The metabolism of D-galactose in Pseudomonas saccharophila. , 1957, The Journal of biological chemistry.

[2]  M. Wheelis,et al.  The genetic control of dissimilatory pathways in Pseudomonas putida. , 1970, Genetics.

[3]  J. Poindexter.  BIOLOGICAL PROPERTIES AND CLASSIFICATION OF THE CAULOBACTER GROUP , 1964, Bacteriological reviews.

[4]  G. Hegeman,et al.  Genetic Control of the β-Ketoadipate Pathway in Pseudomonas aeruginosa , 1968 .

[5]  L. N. Ornston,et al.  Regulation of catabolic pathways in Pseudomonas. , 1971, Bacteriological reviews.

[6]  L. Shapiro,et al.  Effect of dibutyryladenosine 3':5'-cyclic monophosphate on growth and differentiation in Caulobacter crescentus. , 1972, Proceedings of the National Academy of Sciences of the United States of America.

[7]  J. G. Shedlarski.  Glucose-6-phosphate dehydrogenase from Caulobacter crescentus. , 1974, Biochimica et biophysica acta.

[8]  G. Hegeman,et al.  Clustering of Functionally Related Genes in Pseudomonas aeruginosa , 1969, Journal of bacteriology.

[9]  K. Wallenfels,et al.  [22] β-d-galactose dehydrogenase from Pseudomonas saccharophila , 1966 .

[10]  L. Shapiro,et al.  Effect of Carbon Source and the Role of Cyclic Adenosine 3′,5′-Monophosphate on the Caulobacter Cell Cycle , 1977, Journal of bacteriology.

[11]  L. Shapiro,et al.  Effect of 3':5'-cyclic GMP derivatives on the formation of Caulobacter surface structures. , 1976, Proceedings of the National Academy of Sciences of the United States of America.

[12]  C. W. Shuster.  [92] 2-Keto-3-deoxy-6-phosphogalactonic acid aldolase , 1966 .