Molecular analysis of the UV‐inducible pili operon from Sulfolobus acidocaldarius

Marleen Van Wolferen,Małgorzata Ajon,Sonja‐Verena Albers,Arnold J M Driessen

doi:10.1002/mbo3.128

Marleen Van Wolferen, Małgorzata Ajon + Show 2 more

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https://doi.org/10.1002/mbo3.128

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Abstract

Upon ultraviolet (UV) stress, hyperthermophilic Sulfolobus species show a highly induced transcription of a gene cluster responsible for pili biogenesis: the UV-inducible pili operon (ups operon). This operon is involved in UV-induced pili assembly, cellular aggregation, and subsequent DNA exchange between cells. As the system increases the fitness of Sulfolobus cells after UV light exposure, we assume that transfer of DNA takes place in order to repair UV-induced DNA damages via homologous recombination. Here, we studied all genes present in the ups cluster via gene deletion analysis with a focus on UpsX, a protein that shows no identifiable functional domains. UspX does not seem to be structurally essential for UV-induced pili formation and cellular aggregation, but appears to be important for efficient DNA transfer. In addition, we could show that pilin subunits UpsA and UpsB probably both function as major pilin subunits in the ups pili.

Highlights

Upon ultraviolet (UV) stress Sulfolobus species show a high upregulation of a gene cluster encoding proteins responsible for formation of type IV pili (T4P) (Frols et al 2007; Gotz et al 2007): the ups operon (UV-inducible pili operon of Sulfolobus) (Frols et al 2008)
As the system increases the fitness of Sulfolobus cells after UV light exposure, we assume that transfer of DNA takes place in order to repair UV-induced DNA damages via homologous recombination
T4P have shown to be involved in numerous functions both in bacteria as well as in archaea

Summary

Introduction

Upon ultraviolet (UV) stress Sulfolobus species show a high upregulation of a gene cluster encoding proteins responsible for formation of type IV pili (T4P) (Frols et al 2007; Gotz et al 2007): the ups operon (UV-inducible pili operon of Sulfolobus) (Frols et al 2008). An additional phenotypic characteristic of UV-stressed Sulfolobus cells is the formation of large cellular aggregates (Frols et al 2008), which was shown to be mediated by ups pili in a species-specific manner (Ajon et al 2011). Because the aggregation was shown to be inducible by the DNA strand-break-inducing agent bleomycin, the first trigger for pili formation and subsequent aggregation is thought to be the sensing of DSBs in the DNA (Frols et al 2008). The mechanism behind this process remains unknown.

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