Affiliation:
1. Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01002
Abstract
In
Klebsiella aerogenes
W70, there is an inducible pathway for the catabolism of ribitol consisting of at least two enzymes, ribitol dehydrogenase (RDH) and
d
-ribulokinase (DRK). These two enzymes are coordinately controlled and induced in response to
d
-ribulose, an intermediate of the pathway. Whereas wild-type
K. aerogenes
W70 are unable to utilize xylitol as a carbon and energy source, mutants constitutive for the ribitol pathway are able to utilize RDH to oxidize the unusual pentitol, xylitol, to
d
-xylulose. These mutants are able to grow on xylitol, presumably by utilization of the
d
-xylulose produced. Mutants constitutive for
l
-fucose isomerase can utilize the isomerase to convert
d
-arabinose to
d
-ribulose. In the presence of
d
-ribulose, RDH and DRK are induced, and such mutants are thus able to phosphorylate the
d
-ribulose by using the DRK of the ribitol pathway. Derivatives of an
l
-fucose isomerase-constitutive mutant were plated on
d
-arabinose, ribitol, and xylitol to select and identify mutations in the ribitol pathway. Using the transducing phage PW52, we were able to demonstrate genetic linkage of the loci involved. Three-point crosses, using constitutive mutants as donors and RDH
−
, DRK
−
double mutants as recipients and selecting for DRK
+
transductants on
d
-arabinose, resulted in DRK
+
RDH
+
-constitutive, DRK
+
RDH
+
-inducible, and DRK
+
RDH
−
-inducible transductants but no detectable DRK
+
RDH
−
constitutive transductants, data consistent with the order
rbtC-rbtD-rbtK
, where
rbtC
is a control site and
rbtD
and
rbtK
correspond to the sites for the sites for the enzymes RDH and DRK, respectively.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
38 articles.
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