L-Arabinose-sensitive, L-ribulose 5-phosphate 4-epimerase-deficient mutants of Escherichia coli.
Englesberg, E. (University of Pittsburgh, Pittsburgh, Pa.), R L. Anderson, R. Weinberg, N. Lee, P. Hoffee, G. Huttenhauer, and H. Boyer. l-Arabinose-sensitive, l-ribulose 5-phosphate 4-epimerase-deficient mutants of Escherichia coli. J. Bacteriol. 84:137-146. 1962-l-Arabinose-negative mutants of Escherichia coli B/r, ara-53 and ara-139, are deficient in the enzyme l-ribulose 5-phosphate 4-epimerase; ara-53, further analyzed, accumulates large quantities of l-ribulose 5-phosphate when incubated with l-arabinose. The mutant sites are closely linked to the left of the previously ordered l-arabinose mutant sites, and probably represent the structural gene for l-ribulose 5-phosphate 4-epimerase (gene D) in the l-arabinose operon. The inducible levels of l-arabinose isomerase and l-ribulose 5-phosphate 4-epimerase vary correspondingly as a result of mutation in the structural gene for l-ribulokinase (gene B), further substantiating the dual structural and regulatory function of this gene locus. Ara-53 and ara-139 are strongly inhibited by l-arabinose and give rise to l-arabinose-resistant mutants. The one resistant mutant analyzed still lacks the 4-epimerase but is deficient in l-ribulokinase and has increased l-arabinose isomerase activity, a characteristic of a type of mutation in the B gene. It is proposed that accumulation of l-ribulose 5-phosphate is responsible for the inhibition, and that mutation to resistance will involve mutation in the A, B, C, permease, or repressor genes, thus providing a direct method for isolating these types of l-arabinose-negative mutants. Glucose prevents and cures the l-arabinose inhibition.
E
E
ENGLESBERG
R L
RL
ANDERSON
R
R
WEINBERG
N
N
LEE
P
P
HOFFEE
G
G
HUTTENHAUER
H
H
BOYER
D019747:Aldose-Ketose Isomerases; D001089:Arabinose / Q000378:metabolism*; D002238:Carbohydrate Epimerases; D050260:Carbohydrate Metabolism; D004798:Enzymes / Q000172:deficiency*; D004926:Escherichia coli / Q000378:metabolism*; D026901:Membrane Transport Proteins; D009154:Mutation; D009876:Operon; D010428:Pentosephosphates / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D012274:Ribulosephosphates
D004798:Enzymes; D026901:Membrane Transport Proteins; D010428:Pentosephosphates; D012274:Ribulosephosphates; C031524:ribulose 5-phosphate; D001089:Arabinose; D017853:Phosphotransferases (Alcohol Group Acceptor); C022550:ribulokinase; D002238:Carbohydrate Epimerases; C022554:L-ribulosephosphate 4-epimerase; D019747:Aldose-Ketose Isomerases; C019714:D-arabinose isomerase; C019715:L-arabinose isomerase
ARABINOSE/metabolism; ENZYMES/deficiency; ESCHERICHIA COLI/metabolism; PENTOSEPHOSPHATES/metabolism