1887

Abstract

Summary: responds to various stimuli (heat, ethanol and salt stress, energy starvation) with the induction of general stress proteins (GSPs). Most of them belong to the stress and stationary-phase regulon controlled by the alternative sigma factor σ. The majority of σ-dependent proteins are thought to provide a precautionary general stress resistance in stressed or starved cells. In this report, the identification and transcriptional analysis of nine new members of the σ regulon are described. The biochemical function was not determined for any of the proteins encoded by the nine new σ-dependent stress genes, however, similarities to proteins in the databases allowed a distinction between proteins with putative (i-iv) and unknown (v) function. The putative functions of BmrU, YcdF, YdaD, YdaP, YhdN and YocK underline the suggested protective role of σ-dependent GSPs and also elucidate new areas where σ might play an important role. (i) The finding that the operon is under σ control indicates that the elimination of multidrug compounds might be a new function in multiple stress resistance. (ii) YcdF and YdaD resemble NAD(P)-dependent dehydrogenases. Both proteins could be involved in the generation of NAD(P)H and therefore in the maintenance of the intracellular redox balance under stress. (iii) The gene might belong to the increasing number of σ-dependent genes whose orthologues are under the control of σ in indicating that both regulons may fulfil similar functions. (iv) YhdN shows weak similarities to potassium ion channel proteins and YocK shows resemblance to the DnaK suppressor protein DksA. (v) Three new σ-dependent genes ( and ) encoding proteins with still unknown functions were also described. Further analyses of corresponding mutants might allow a first prediction of their function within the framework of the general stress regulon.

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/content/journal/micro/10.1099/13500872-145-4-869
1999-04-01
2019-10-15
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http://instance.metastore.ingenta.com/content/journal/micro/10.1099/13500872-145-4-869
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