1887

Abstract

The genetic loci leading to anaerobic derepression of a protein fusion in a UV-generated mutant strain (UV14) of were identified. The mutant (UV14) was found to harbour two altered loci: one is in the -regulatory gene (fumarate nitrate reduction) where leucine-129 was changed to glutamine (), and the second () is in the promoter region () of the gene apparently affecting the binding of the Fur (ferric uptake regulation) protein. Introduction of an gene into UV14 restored anaerobic repression of and restored the ability of the cells to reduce nitrate. However, when either the or the mutation was introduced into an otherwise wild-type background, only slight anaerobic derepression of was observed. When both the - and -acting mutations (i.e. and ) were combined simultaneously in an otherwise wild-type background, the specific activity of expression was comparable to that of the original mutant strain (UV14). Furthermore, a genetically confirmed double mutant was also similarly derepressed in anaerobic expression. The data presented suggest that the -mutation in UV14 () affects the Fur-binding site in the promoter, while having no effect on Fnr or Arc mediated repression. Also, a second putative Fnr-binding site that straddles the ribosomal binding-site was identified in the gene.

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/content/journal/micro/10.1099/00221287-139-11-2677
1993-11-01
2019-11-17
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http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-139-11-2677
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