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Molecular analysis of the UV-inducible pili operon from Sulfolobus acidocaldarius.

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.

SUBMITTER: van Wolferen M

PROVIDER: S-EPMC3892339 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Molecular analysis of the UV-inducible pili operon from Sulfolobus acidocaldarius.

van Wolferen Marleen M Ajon Małgorzata M Driessen Arnold J M AJ Albers Sonja-Verena SV

MicrobiologyOpen 20130919 6

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 reco ...[more]

PMID: 24106028

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A conserved hexanucleotide motif is important in UV-inducible promoters in Sulfolobus acidocaldarius.

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Transcription profiling of hyperthermophilic crenarchaea Sulfolobus solfataricus and Sulfolobus acidocaldarius to UV irradiation

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Effect of UV irradiation on Sulfolobus acidocaldarius and involvement of the general transcription factor TFB3 in the early UV response.

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Molecular characteristics of spontaneous deletions in the hyperthermophilic archaeon Sulfolobus acidocaldarius.

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Genes of de novo pyrimidine biosynthesis from the hyperthermoacidophilic crenarchaeote Sulfolobus acidocaldarius: novel organization in a bipolar operon.

Project description:Sequencing a 8,519-bp segment of the Sulfolobus acidocaldarius genome revealed the existence of a tightly packed bipolar pyrimidine gene cluster encoding the enzymes of de novo UMP synthesis. The G+C content of 35.3% is comparable to that of the entire genome, but intergenic regions exhibit a considerably lower percentage of strong base pairs. Coding regions harbor the classical excess of purines on the coding strand, whereas intergenic regions do not show this bias. Reverse transcription-PCR and primer extension experiments demonstrated the existence of two polycistronic messengers, pyrEF-orf8 and pyrBI-orf1-pyrCD-orf2-orf3-orf4, initiated from a pair of divergent and partially overlapping promoters. The gene order and the grouping in two wings of a bipolar operon constitute a novel organization of pyr genes that also occurs in the recently determined genome sequences of Sulfolobus solfataricus P2 and Sulfolobus tokodaii strain 7; the configuration appears therefore characteristic of Sulfolobus. The quasi-leaderless pyrE and pyrB genes do not bear a Shine-Dalgarno sequence, whereas the initiation codon of promoter-distal genes is preceded at an appropriate distance by a sequence complementary to the 3' end of 16S rRNA. The polycistronic nature of the pyr messengers and the existence of numerous overlaps between contiguous open reading frames suggests the existence of translational coupling. pyrB transcription was shown to be approximately twofold repressed in the presence of uracil. The mechanism underlying this modulation is as yet unknown, but it appears to be of a type different from the various attenuation-like mechanisms that regulate pyrB transcription in bacteria. In contrast, the pyrE-pyrB promoter/control region harbors direct repeats and imperfect palindromes reminiscent of target sites for the binding of a hypothetical regulatory protein(s).

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Effect of UV irradiation on Sulfolobus acidocaldarius and involvement of the general transcription factor TFB3 in early UV response

Project description:Extremophilic archaea like all organisms experience potentially life-threatening conditions including UV light, which induces severe DNA damage. Since the alternative general transcription factor (GTF) TFB3 has been proposed to play a key role in UV stress response in the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius, we investigated the expression of TFB3 on protein level including in vivo protein-protein interaction studies, tfb3 reporter gene assays and creation of a tfb3 insertion mutant to study early differential gene expression upon UV treatment (after 45 and 90 minutes). Our results allowed differentiating between the TFB3-dependent and TFB3-independent early UV response in S. acidocaldarius. The early TFB3-independent UV response includes the repression of nucleotide biosynthesis and transport, replication and cell cycle progression in order to allow DNA repair. The TFB3-dependent UV response is characterized by the early induction of TFB3, which is a prerequisite for the following TFB3-dependent expression of genes involved in ups pili formation and the Ced DNA importer. Both structures facilitate the transfer of DNA to allow repair via homologous recombination. The fact, that all genes are downregulated in the tfb3 mutant compared to the reference strain, confirms the hypothesis that TFB3 acts as an activator of transcription.

2020-03-20 | GSE112071 | GEO

Participation of UV-regulated Genes in the Response to Helix-distorting DNA Damage in the Thermoacidophilic Crenarchaeon Sulfolobus acidocaldarius.

Project description:Several species of Sulfolobales have been used as model organisms in the study of response mechanisms to ultraviolet (UV) irradiation in hyperthermophilic crenarchaea. To date, the transcriptional responses of genes involved in the initiation of DNA replication, transcriptional regulation, protein phosphorylation, and hypothetical function have been observed in Sulfolobales species after UV irradiation. However, due to the absence of knockout experiments, the functions of these genes under in situ UV irradiation have not yet been demonstrated. In the present study, we constructed five gene knockout strains (cdc6-2, tfb3, rio1, and two genes encoding the hypothetical proteins, Saci_0951 and Saci_1302) of Sulfolobus acidocaldarius and examined their sensitivities to UV irradiation. The knockout strains exhibited significant sensitivities to UV-B irradiation, indicating that the five UV-regulated genes play an important role in responses to UV irradiation in vivo. Furthermore, Δcdc6-2, Δrio1, ΔSaci_0951, and Δtfb3 were sensitive to a wide variety of helix-distorting DNA lesions, including UV-induced DNA damage, an intra-strand crosslink, and bulky adducts. These results reveal that cdc6-2, tfb3, rio1, and Saci_0951 are play more important roles in broad responses to helix-distorting DNA damage than in specific responses to UV irradiation.

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