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Constitutive activation of L-fucose genes by an unlinked mutation in Escherichia coli

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Constitutive activation of L-fucose genes by an unlinked mutation in Escherichia coli
 
Creator Chen , YM
Chakrabarti, T
Lin , EC
 
Subject QR Microbiology
 
Description Wild-type Escherichia coli cannot grow on L-1,2-propanediol; mutants that can do so have increased basal activity of an NAD-linked L-1,2-propanediol oxidoreductase. This enzyme belongs to the L-fucose system and functions normally as L-lactaldehyde reductase during fermentation of the methylpentose. In wild-type cells, the activity of this enzyme is fully induced only anaerobically. Continued aerobic selection for mutants with an improved growth rate on L-1,2-propanediol inevitably leads to full constitutive expression of the oxidoreductase activity. When this occurs, L-fuculose 1-phosphate aldolase concomitantly becomes constitutive, whereas L-fucose permease, L-fucose isomerase, and L-fuculose kinase become noninducible. It is shown in this study that the noninducibility of the three proteins can be changed by two different kinds of suppressor mutations: one mapping external to and the other within the fuc gene cluster. Both mutations result in constitutive synthesis of the permease, the isomerase, and the kinase, without affecting synthesis of the oxidoreductase and the aldolase. Since expression of the fuc structural genes is activated by a protein specified by the regulator gene fucR, and since all the known genes of the fuc system are clustered at minute 60.2 of the chromosome, the external gene in which the suppressor mutation can occur probably has an unrelated function in the wild-type strain. The internal suppressor mutation might be either in fucR or in the promoter region of the genes encoding the permease, the isomerase, and the kinase, if these genes belong to the same operon.
 
Publisher ASM
 
Date 1984
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/639/1/tapan1984.pdf
Chen , YM and Chakrabarti, T and Lin , EC (1984) Constitutive activation of L-fucose genes by an unlinked mutation in Escherichia coli. Journal of bacteriology, 159 (2). ISSN 0021-9193
 
Relation http://jb.asm.org/content/159/2/725.long
http://crdd.osdd.net/open/639/