Studies of the FBT family transporters in Leishmania infantum by gene deletion and protein localization.

The protozoan parasite Leishmania has a large family of major facilitator membrane proteins part of the Folate Biopterin Transporter (FBT) family. The chromosome 10 of Leishmania has a cluster of 7 FBT genes including the S-Adenosyl methionine (AdoMet) transporter and the functionally characterized folate transporters FT1 and FT5. Six of the 7 FBT proteins coded by this locus are located at the plasma membrane as determined by gene fusions with the green fluorescent protein.

Characterization of vancomycin-resistance gene clusters in the human intestinal microbiota by metagenomics and culture-enriched metagenomics.

Objectives: To characterize vancomycin-resistance gene clusters and potential -carrying bacteria in the intestinal microbiota of healthy volunteers exposed or not to β-lactam antibiotics.

Methods: Stool samples were collected before and after 7 days of cefprozil β-lactam antibiotic exposure of 18 participants and six control participants who were not exposed to the antibiotic at the same time points. Metagenomic sequencing and culture-enriched metagenomic sequencing (with and without β-lactam selection) were used to characterize gene clusters and determine potential -carrying bacteria.

Culture-enriched human gut microbiomes reveal core and accessory resistance genes.

Background: Low-abundance microorganisms of the gut microbiome are often referred to as a reservoir for antibiotic resistance genes. Unfortunately, these less-abundant bacteria can be overlooked by deep shotgun sequencing. In addition, it is a challenge to associate the presence of resistance genes with their risk of acquisition by pathogens.

Analysis of membrane-enriched and high molecular weight proteins in Leishmania infantum promastigotes and axenic amastigotes.

Membrane and high molecular weight (HMW) proteins tend to be underrepresented in proteome analyses. Here, we optimized a protocol designed for the extraction and purification of membranes from the protozoan parasite Leishmania using a combination of serial centrifugation and free-flow zone electrophoresis (ZE-FFE). We also enriched for Leishmania HMW proteins from total extracts using the Gelfree 8100 fractionation system.

Probing tRNA interaction with biogenic polyamines.

Biogenic polyamines are found to modulate protein synthesis at different levels. This effect may be explained by the ability of polyamines to bind and influence the secondary structure of tRNA, mRNA, and rRNA. We report the interaction between tRNA and the three biogenic polyamines putrescine, spermidine, spermine, and cobalt(III)hexamine at physiological conditions, using FTIR spectroscopy, capillary electrophoresis, and molecular modeling.

High affinity S-Adenosylmethionine plasma membrane transporter of Leishmania is a member of the folate biopterin transporter (FBT) family.

S-Adenosylmethionine (AdoMet) is an important methyl group donor that plays a central role in many essential biochemical processes. The parasite Leishmania can both synthesize and transport AdoMet. Leishmania cells resistant to the antifolate methotrexate due to a rearrangement in folate biopterin transporter (FBT) genes were cross-resistant to sinefungin, an AdoMet analogue.

Functional analysis and complex gene rearrangements of the folate/biopterin transporter (FBT) gene family in the protozoan parasite Leishmania.

The protozoan parasite Leishmania is a folic acid auxotroph. Previous work has led to the characterization of the main folate transporter FT1. FT1 is part of the folate/biopterin transporter (FBT) family and Leishmania with its 14 members is, of all sequenced organisms, the one with the most FBTs.

Modulation of gene expression in drug resistant Leishmania is associated with gene amplification, gene deletion and chromosome aneuploidy.

Background: Drug resistance can be complex, and several mutations responsible for it can co-exist in a resistant cell. Transcriptional profiling is ideally suited for studying complex resistance genotypes and has the potential to lead to novel discoveries. We generated full genome 70-mer oligonucleotide microarrays for all protein coding genes of the human protozoan parasites Leishmania major and Leishmania infantum.

AZT binds RNA at multiple sites.

Azidothymidine (AZT) is a widely used inhibitor of type I human immunodeficiency virus (HIV) reverse transcriptase that act as a DNA chain terminator. Studies have shown primer unblocking and rescue of DNA synthesis AZT-resistant HIV-1 reverse transcriptase on DNA and RNA templates. Our recent study showed AZT bindings to the G-C, A-T base pairs and the backbone phosphate group of DNA duplex resulting in partial DNA conformational changes.

Structural analysis of DNA interactions with biogenic polyamines and cobalt(III)hexamine studied by Fourier transform infrared and capillary electrophoresis.

Biogenic polyamines, such as putrescine, spermidine, and spermine are small organic polycations involved in numerous diverse biological processes. These compounds play an important role in nucleic acid function due to their binding to DNA and RNA. It has been shown that biogenic polyamines cause DNA condensation and aggregation similar to that of inorganic cobalt(III)hexamine cation, which has the ability to induce DNA conformational changes.

AZT-DNA interaction.

Oxidative DNA damage has been reported in fetal tissues by exposure to 3'-azido-3'-deoxythymidine (AZT). AZT has been used effectively for the treatment of human immunodeficiency virus-1 (HIV-1) and AIDS. It showed in vitro to block the nucleoside-binding site of the viral reverse transcriptase and to inhibit DNA replication by chain termination.