Integrase

HIV-1 reverse transcription is achieved in the newly infected cell before viral DNA (vDNA) nuclear import. Reverse transcriptase (RT) has previously been shown to function as a molecular motor, dismantling the nucleocapsid complex that binds the viral genome as soon as plus-strand DNA synthesis initiates. We first propose a detailed model of this dismantling in close relationship with the sequential conversion from RNA to double-stranded (ds) DNA, focusing on the nucleocapsid protein (NCp7). The HIV-1 DNA-containing preintegration complex (PIC) resulting from completion of reverse transcription is translocated through the nuclear pore. The PIC nucleoprotein architecture is poorly understood but contains at least two HIV-1 proteins initially from the virion core, namely Integrase (IN) and the viral protein r (Vpr). We next present a set of electron micrographs supporting that Vpr behaves as a DNA architectural protein, initiating multiple DNA bridges over more than 500 base pairs (bp). These complexes are shown to interact with NCp7 bound to single-stranded nucleic acid regions that are thought to maintain IN binding during dsDNA synthesis, concurrently with nucleocapsid complex dismantling. This unexpected binding of Vpr conveniently leads to a compacted but filamentous folding of the vDNA that should favor its nuclear import. Finally, nucleocapsid-like aggregates engaged in dsDNA synthesis appear to efficiently bind to F-actin filaments, a property that may be involved in targeting complexes to the nuclear envelope. More generally, this article highlights unique possibilities offered by in vitro reconstitution approaches combined with macromolecular imaging to gain insights into the mechanisms that alter the nucleoprotein architecture of the HIV-1 genome, ultimately enabling its insertion into the nuclear chromatin.

HIV integrase is a 32 kDa protein produced from the C-terminal portion of the Pol gene product, and is
an attractive target for new anti-HIV drugs. Integrase is an enzyme produced by a retrovirus (such as
HIV) that enables its genetic material to be integrated into the DNA of the infected cell. Raltegravir and
Elvitegravir are two important drugs against integrase.

Rotifers of class Bdelloidea, a group of aquatic invertebrates in which males and meiosis have never been documented, are also unusual in their lack of multicopy LINE-like and gypsy-like retrotransposons, groups inhabiting the genomes of nearly all other metazoans. Bdelloids do contain numerous DNA transposons, both intact and decayed, and domesticated Penelope-like retroelements Athena, concentrated at telomeric regions. Here we describe two LTR retrotransposons, each found at low copy number in a different bdelloid species, which define a clade different from previously known clades of LTR retrotransposons. Like bdelloid DNA transposons and Athena, these elements have been found preferentially in telomeric regions. Unlike bdelloid DNA transposons, many of which are decayed, the newly described elements, named Vesta and Juno, inhabiting the genomes of Philodina roseola and Adineta vaga, respectively, appear to be intact and to represent recent insertions, possibly from an exogenous source. We describe the retrovirus-like structure of the new elements, containing gag, pol, and env-like open reading frames, and discuss their possible origins, transmission, and behavior in bdelloid genomes.

The activity of the Integrase (Int) protein en- coded by coliphage HK022 was tested in a human cell culture. Plasmids were constructed as substrates that carry the sites of the integration reaction (attP and attB) or the sites of excision (attL and attR). The site-specific recombination reactions were monitored in cis and in trans configurations by the expression of the

A total of 62 Acinetobacter baumannii isolates including 29 imipenem resistant, 23 imipenem susceptible and 10 environmental isolates were analyzed based on integron and integron gene cassette array (I-GCA) PCR and DNA sequences. Two types of class 1 integron were found based on their cassette arrays. The integron class 1 with a 2.6 kb size (Int1-A) has the cassette order of aaC(6')-Im followed by another gene cassette aadA1 disrupted by IS26 transposase, while the another class 1 integron with 2.8 kb size (Int1-B) has the gene cassette order of aacC1 followed by orfX, orfX', IS 26 transposase and aadA1. PCR mapping detect the distribution of such integron types within the isolates. Integron gene cassette array PCR (I-GCA PCR) typing gave 20 profiles while PFGE typing gave 18 profiles with 16 types and 2 subtypes. The major profile I of I-GCA PCR equivalent to profile A of PFGE was the dominant profile covering most of the clinical and environmental imipenem resistant isolates while the second largest profile XII of I-GCA PCR or profile M of PFGE was found in the imipenem susceptible isolates. Both integron types Int1-A and Int1-B were mostly restricted to imipenem resistant outbreak strains of the major profile I of I-GCA PCR or profile A of PFGE. I-GCA PCR based typing gave similar result to that of PFGE by sharing all the imipenem resistant strains of distinct profile I of I-GCA PCR in the profile A of PFGE which was responsible for the present A. baumannii outbreak. These results indicate that I-GCA PCR alone or coupled with other typing method would be a rapid tool for epidemiological study for bacteria that bear integron.

Integrase (IN) is one of the three human immunodeficiency virus type 1 (HIV-1) enzymes essential for effective viral replication. S-1360 is a potent and selective inhibitor of HIV-1 IN. In this work, we have carried out molecular dynamics (MD) simulations using a hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) approach, to determine the protein-ligand interaction energy for S-1360 and two analogues. Analysis of the MD trajectories reveals that the strongest protein-inhibitor interactions, observed in the three studied complexes, are established with Lys-159 residue and Mg(2+) cation. Calculations of binding energy using BLYP/MM level of theory reveal that there is a direct relationship between this theoretical computed property and the experimental determined anti-HIV activity.

A novel compound inhibiting HIV-1 integrase has been identified by means of virtual screening techniques. A small family of structurally related molecules has been synthesized and biologically evaluated with some of the compounds possessing micromolar activity both in enzymatic and cellular assays.A novel compound inhibiting HIV-1 integrase has been identified by means of virtual screening techniques. A small family of structurally related molecules has been synthesized and biologically evaluated with some of the compounds possessing micromolar activity both in enzymatic and cellular assays.

Twenty-two quinazoline derivatives have been synthesised and examined for their anti-tumour activity against three tumour cell lines, namely human breast cancer cell line (MCF-7), human cervical cancer cell line (HeLa) and human hepatoma cell line (HepG2). Twelve of the tested compounds have shown promising anti-tumour activity with an IC(50) range of 5.0-9.7 µg/mL. Regarding the spectrum of activity, five compounds exhibited interesting anti-proliferative properties against the three tested cell lines comparable to the reference drug (dasatinib).