Project description:In the field of biocatalysis and the development of a bio-based economy, hemicellulases have attracted great interest for various applications in industrial processes. However, the study of the catalytic activity of the lignocellulose-degrading enzymes needs to be improved to achieve the efficient hydrolysis of plant biomasses. In this framework, hemicellulases from hyperthermophilic archaea show interesting features as biocatalysts and provide many advantages in industrial applications thanks to their stability in the harsh conditions encountered during the pretreatment process. However, the hemicellulases from archaea are less studied compared to their bacterial counterpart, and the activity of most of them has been barely tested on natural substrates. Here, we investigated the hydrolysis of xyloglucan oligosaccharides from two different plants by using, both synergistically and individually, three glycoside hydrolases from Saccharolobus solfataricus: a GH1 β-gluco-/β-galactosidase, a α-fucosidase belonging to GH29, and a α-xylosidase from GH31. The results showed that the three enzymes were able to release monosaccharides from xyloglucan oligosaccharides after incubation at 65 °C. The concerted actions of β-gluco-/β-galactosidase and the α-xylosidase on both xyloglucan oligosaccharides have been observed, while the α-fucosidase was capable of releasing all α-linked fucose units from xyloglucan from apple pomace, representing the first GH29 enzyme belonging to subfamily A that is active on xyloglucan.
Project description:Chromatin proteins competes with the transcription machinery for access to genomic DNA and suppress cryptic promoters. CRISPR arrays form the physical memory of CRISPR adaptive immune systems. The incorporation of virus-derived AT-rich DNA into CRISPR arrays renders them prone to harbouring cryptic promoters. Sulfolobales feature extremely long CRISPR arrays spanning several kilobases as well as a CRISPR-specific chromatin protein termed Cbp1. Altered Cbp1 expression affects transcription from CRISPR arrays in multiple ways, but the mechanistic basis remains to be understood. Here, we show that Cbp1 recruits the general chromatin protein Cren7 to form a heteromeric chromatin complex at CRISPR arrays. Cbp1-CreN7 chromatinisation plays a dual role in the transcription of CRISPR array. It suppresses spurious transcription from cryptic CRISPR array-internal promoters via steric occlusion of the transcription machinery while enhancing transcription from promoters in the CRISPR leaders. Our results show that Cbp1-CreN7 chromatinization drives the coordinated transcription of long CRISPR arrays. Additional binding sites of Cbp1 associated with transposases and the leaders of alternative CRISPR arrays hint on a wider regulatory function of Cbp1 linking defense systems and mobile genetic elements.
Project description:Chromatin proteins competes with the transcription machinery for access to genomic DNA and suppress cryptic promoters. CRISPR arrays form the physical memory of CRISPR adaptive immune systems. The incorporation of virus-derived AT-rich DNA into CRISPR arrays renders them prone to harbouring cryptic promoters. Sulfolobales feature extremely long CRISPR arrays spanning several kilobases as well as a CRISPR-specific chromatin protein termed Cbp1. Altered Cbp1 expression affects transcription from CRISPR arrays in multiple ways, but the mechanistic basis remains to be understood. Here, we show that Cbp1 recruits the general chromatin protein Cren7 to form a heteromeric chromatin complex at CRISPR arrays. Cbp1-CreN7 chromatinisation plays a dual role in the transcription of CRISPR array. It suppresses spurious transcription from cryptic CRISPR array-internal promoters via steric occlusion of the transcription machinery while enhancing transcription from promoters in the CRISPR leaders. Our results show that Cbp1-CreN7 chromatinization drives the coordinated transcription of long CRISPR arrays. Additional binding sites of Cbp1 associated with transposases and the leaders of alternative CRISPR arrays hint on a wider regulatory function of Cbp1 linking defense systems and mobile genetic elements.
Project description:RecA ATPases are a family of proteins that catalyzes the exchange of complementary DNA regions via homologous recombination. They are conserved from bacteria to humans and are crucial for DNA damage repair and genetic diversity. In this work, Knadler et al. examine how ATP hydrolysis and divalent cations impact the recombinase activity of Saccharolobus solfataricus RadA protein (ssoRadA). They find that the ssoRadA-mediated strand exchange depends on ATPase activity. The presence of Manganese reduces ATPase activity and enhances strand exchange, while calcium inhibits ATPase activity by preventing ATP binding to the protein, yet destabilizes the nucleoprotein ssoRadA filaments, allowing strand exchange regardless of the ATPase activity. Although RecA ATPases are highly conserved, this research offers intriguing new evidence that each member of the family requires individual evaluation.