Affiliation:
1. Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01002
Abstract
Klebsiella aerogenes
strain W70 has separate inducible pathways for the degradation of the pentitols ribitol and
d
-arabitol. These pathways are closely linked genetically as determined by transduction with phage PW52. There are two regulatory sites for the ribitol catabolic pathway as defined by loci for mutations to constitutive synthesis of ribitol dehydrogenase and
d
-ribulokinase,
rbtB
and
rbtC
. The two control sites are separated by a site represented by the
dalB22
mutation. This mutation deprives the cell of the ability to induce synthesis of
d
-arabitol dehydrogenase and
d
-xylulokinase activities. Two additional regulatory mutations for the
d
-arabitol pathway,
dalC31
and
dalC37
, map to the opposite side of
rbtB13
relative to
dalB22
. The order of the genetic sites thus far determined for this region is
dalK-dalD-dalC31, dalC37-rbtB13-dalB22-rbtC14-rbtD-rbtK
, where
dalK
and
dalD
represent structural genes for the kinase and dehydrogenase of the
d
-arabitol pathway, respectively, and
rbtK
and
rbtD
represent the corresponding genes for the ribitol pathway. The two mutations that lead to constitutive synthesis of the
d
-arabitol-induced enzymes,
dalC31
and
dalC37
, have different phenotypes with regard to their response to xylitol. The growth of
dalC31
is inhibited by xylitol, but the toxicity can be reduced by increasing the levels of ribitol dehydrogenase either by induction with ribitol or by selection of a ribitol dehydrogenase-constitutive mutation.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
32 articles.
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