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The metabolism of gluconate in Escherichia coli . The subsidiary system and the nature of the gnt S gene
Author(s) -
Istúriz Tomás,
Celaya Joseba
Publication year - 1997
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620370205
Subject(s) - mutant , escherichia coli , tn10 , permease , locus (genetics) , negative regulator , gene , regulator , pep group translocation , biochemistry , regulator gene , biology , repressor , chemistry , transposable element , genetics , regulation of gene expression , gene expression
The transport and phosphorylation of gluconate in E. coli occurs through two systems (GntI and GntII) which duplicate activities. bio H‐asddeletion mutants do not grow on media with gluconate as sole carbon source because they lack the GntI system and do not express GntII. Although E. coli C177 is a Δ( bio H‐ asd ) mutant, it carries the pyr B linked mutation gnt 177 that enables it to metabolize this substrate through inducible expression of the GntII system. Several gnt S derivatives which are unable to grow on gluconate were isolated from E. coli C177 by spontaneous curing of the transposon Tn10 previously inserted at the gnt S locus (zjf::Tn10, min 95.3). A representative gnt S mutant, E. coli TI141A retained the ability to take up gluconate but had lost the thermosensitive gluconokinase activity (gene gnt V, min 96.9). Furthermore, it could be demonstrated that gnt V is repressed in E. coli TI141A. The results indicate that gnt S might specify a trans‐acting positive regulator involved in the control of at least the expression of the thermosensitive gluconokinase (GntII), instead of a gluconate uptake system as it was previously postulated. Likewise, these results can be used to reconsider whether the locus altered by the gnt 177 lesion is allelic with that of the GntII permease instead of a regulator, as it was originally postulated.