Integrase-LEDGF/p75 complex triggers the formation of biomolecular condensates that modulate HIV-1 integration efficiency in vitro.

The pre-integration steps of the HIV-1 viral cycle are some of the most valuable targets of recent therapeutic innovations. HIV-1 integrase (IN) displays multiple functions, thanks to its considerable conformational flexibility. Recently, such flexible proteins have been characterized by their ability to form biomolecular condensates as a result of Liquid-Liquid-Phase-Separation (LLPS), allowing them to evolve in a restricted microenvironment within cells called membrane-less organelles (MLO).

The kinesin Kif21b regulates radial migration of cortical projection neurons through a non-canonical function on actin cytoskeleton.

Completion of neuronal migration is critical for brain development. Kif21b is a plus-end-directed kinesin motor protein that promotes intracellular transport and controls microtubule dynamics in neurons. Here we report a physiological function of Kif21b during radial migration of projection neurons in the mouse developing cortex.

Biological and Structural Analyses of New Potent Allosteric Inhibitors of HIV-1 Integrase.

HIV-1 integrase-LEDGF allosteric inhibitors (INLAIs) share the binding site on the viral protein with the host factor LEDGF/p75. These small molecules act as molecular glues promoting hyper-multimerization of HIV-1 IN protein to severely perturb maturation of viral particles. Herein, we describe a new series of INLAIs based on a benzene scaffold that display antiviral activity in the single digit nanomolar range.

Structural insights into RNA-mediated transcription regulation in bacteria.

RNA can regulate its own synthesis without auxiliary proteins. For example, U-rich RNA sequences signal RNA polymerase (RNAP) to pause transcription and are required for transcript release at intrinsic terminators in all kingdoms of life. In contrast, the regulatory RNA putL suppresses pausing and termination in cis.

Publisher Correction: Post-translational modifications in DNA topoisomerase 2α highlight the role of a eukaryote-specific residue in the ATPase domain.

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Post-translational modifications in DNA topoisomerase 2α highlight the role of a eukaryote-specific residue in the ATPase domain.

Type 2 DNA topoisomerases (Top2) are critical components of key protein complexes involved in DNA replication, chromosome condensation and segregation, as well as gene transcription. The Top2 were found to be the main targets of anticancer agents, leading to intensive efforts to understand their functional and physiological role as well as their molecular structure. Post-translational modifications have been reported to influence Top2 enzyme activities in particular those of the mammalian Top2α isoform.

Structural insight into negative DNA supercoiling by DNA gyrase, a bacterial type 2A DNA topoisomerase.

Type 2A DNA topoisomerases (Topo2A) remodel DNA topology during replication, transcription and chromosome segregation. These multisubunit enzymes catalyze the transport of a double-stranded DNA through a transient break formed in another duplex. The bacterial DNA gyrase, a target for broad-spectrum antibiotics, is the sole Topo2A enzyme able to introduce negative supercoils.

Modular architecture of eukaryotic RNase P and RNase MRP revealed by electron microscopy.

Ribonuclease P (RNase P) and RNase MRP are closely related ribonucleoprotein enzymes, which process RNA substrates including tRNA precursors for RNase P and 5.8 S rRNA precursors, as well as some mRNAs, for RNase MRP. The structures of RNase P and RNase MRP have not yet been solved, so it is unclear how the proteins contribute to the structure of the complexes and how substrate specificity is determined.

Insights into the structure of the CCR4-NOT complex by electron microscopy.

The CCR4-NOT complex is a deadenylation complex, which plays a major role for mRNA stability. The complex is conserved from yeast to human and consists of nine proteins NOT1-NOT5, CCR4, CAF1, CAF40 and CAF130. We have successfully isolated the complex using a Protein A tag on NOT1, followed by cross-linking on a glycerol gradient.

Proteome organization in a genome-reduced bacterium.

The genome of Mycoplasma pneumoniae is among the smallest found in self-replicating organisms. To study the basic principles of bacterial proteome organization, we used tandem affinity purification-mass spectrometry (TAP-MS) in a proteome-wide screen. The analysis revealed 62 homomultimeric and 116 heteromultimeric soluble protein complexes, of which the majority are novel.

Purification of nuclear poly(A)-binding protein Nab2 reveals association with the yeast transcriptome and a messenger ribonucleoprotein core structure.

Nascent mRNAs produced by transcription in the nucleus are subsequently processed and packaged into mRNA ribonucleoprotein particles (messenger ribonucleoproteins (mRNPs)) before export to the cytoplasm. Here, we have used the poly(A)-binding protein Nab2 to isolate mRNPs from yeast under conditions that preserve mRNA integrity. Upon Nab2-tandem affinity purification, several mRNA export factors were co-enriched (Yra1, Mex67, THO-TREX) that were present in mRNPs of different size and mRNA length.

A different conformation for EGC stator subcomplex in solution and in the assembled yeast V-ATPase: possible implications for regulatory disassembly.

Vacuolar ATPases (V-ATPases) are ATP-dependent proton pumps that maintain the acidity of cellular compartments. They are composed of a membrane-integrated proton-translocating V(0) and an extrinsic cytoplasmic catalytic domain V(1), joined by several connecting subunits. To clarify the arrangement of these peripheral connections and their interrelation with other subunits of the holocomplex, we have determined the solution structures of isolated EG and EGC connecting subcomplexes by small angle X-ray scattering and the 3D map of the yeast V-ATPase by electron microscopy.