The general transcription factor IID (TFIID) is a critical component of the eukaryotic transcription preinitiation complex (PIC) and is responsible for recognizing the core promoter DNA and initiating PIC assembly. We used cryo-electron microscopy (cryo-EM), chemical crosslinking-mass spectrometry (CX-MS) and biochemical reconstitution to determine the complete molecular architecture of TFIID and define the conformational landscape of TFIID in the process of TATA-box binding protein (TBP) loading onto promoter DNA. Our structural analysis revealed five structural states of TFIID in the presence of TFIIA and promoter DNA, showing that the initial binding of TFIID to the downstream promoter positions the upstream DNA and facilitates scanning of TBP for a TATA-box and the subsequent engagement of the promoter. Our findings provide a mechanistic model for the specific loading of TBP by TFIID onto the promoter.

Rubus species (family Rosaceae) have been cultivated for centuries for their fruits. These and other parts of the plants have been used traditionally for therapeutic purposes. This article highlights these and the potential they can offer. The constituents reported in the various species and those demonstrated to exhibit pharmacological properties have been reviewed. In the search for biologically active compounds, one of the most frequently documented species of the genus is the raspberry plant R. idaeus, the leaves of which have been used traditionally as a uterine relaxant and stimulant during confinement, for the treatment of diarrhoea and similar enteric disorders and as an astringent. Investigations of other Rubus species have been conducted in the last twenty-five years, and have shown possible application for a wide range of indications, including bacterial infections, anxiety, pain and inflammation.

Topoisomerases are involved in controlling and maintaining the topology of DNA and are present in all kingdoms of life. Unlike all other types of topoisomerases, similar type IB enzymes have only been identified in bacteria and eukarya. The only putative type IB topoisomerase in archaea is represented by Methanopyrus kandleri topoisomerase V. Despite several common functional characteristics, topoisomerase V shows no sequence similarity to other members of the same type. The structure of the 61 kDa N-terminal fragment of topoisomerase V reveals no structural similarity to other topoisomerases. Furthermore, the structure of the active site region is different, suggesting no conservation in the cleavage and religation mechanism. Additionally, the active site is buried, indicating the need of a conformational change for activity. The presence of a topoisomerase in archaea with a unique structure suggests the evolution of a separate mechanism to alter DNA.

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