Biology subjects

Ruiz, J. C.

Publications and source records attributed to Ruiz, J. C..

3 recordsLinked to original sources

bioRxiv2020

Biosynthesis and chemical characterization of an intracellular red pigment of Talaromyces islandicus T101

The interest in red colorants by the food industry has been increasing recently due to its wide application in many foods and beverages, and also to the carcinogenic and teratogenic effects of some synthetic dyes. Many ascomycetous fungi are able to synthesize and produce pigments, rendering them as alternative sources of natural dyes that are independent of environmental conditions. Talaromyces islandicus TI01 was isolated from a marine-influenced environment that has been suffering for decades from anthropogenic actions in its body of water. Broth microdilution technique was performed to analyze the antimicrobial activity. For analysis of the cytotoxic activity, the MTT [3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide] assay was conducted. The chemical analysis of the extract was performed by LC/MS (liquid chromatography coupled to mass spectrometry). The minimum bactericidal concentration (MBC) of T. islandicus intracellular red pigmented extract (IRPE) for E. coli ATCC 25922 and S. aureus ATCC 25923 was 1000 g/ml. The minimum inhibitory concentration (MIC) for E. coli was 250 g/mL and for S. aureus 500 g/mL, respectively, whereas for C. tropicalis ATCC 1369 was 62.5 g/mL. IC50 for breast cancer cell line (MCF-7) was 45.43 {+/-} 1.657 g / mL. The major compounds present in the extract were: Luteoskyrin (1) and N-GABA-PP-V (6-[(Z)-2-Carboxyvinyl]-N-GABA-PP-V) (2). The results show that IRPE from T. islandicus TI01 has a prominent antibacterial activity against E. coli and S. aureus, making this pigment interesting for development of new food colorants and/or conservative agents, since these bacteria are food-borne pathogens.

microbiology↗

bioRxiv2020

Kaposi's sarcoma-associated herpesvirus fine-tunes the temporal expression of late genes by manipulating a host RNA quality control pathway

Kaposis sarcoma-associated herpesvirus (KSHV) is a human oncogenic nuclear DNA virus that expresses its genes using the host cell transcription and RNA processing machinery. As a result, KSHV transcripts are subject to degradation by at least two host-mediated nuclear RNA decay pathways, PABPN1 and PAP/{gamma}-mediated RNA decay (PPD) and an ARS2-dependent decay pathway. Here, we present global analyses of viral transcript levels to further understand the roles of these decay pathways in KSHV gene expression. Consistent with our recent report that the KSHV ORF57 protein increases viral transcript stability by impeding ARS2-dependent decay, ARS2 knockdown has little effect on viral gene expression 24 hours after lytic reactivation of wild-type virus. In contrast, inactivation of PPD results in premature accumulation of late transcripts. The up-regulation of late transcripts does not require the primary late gene-specific viral transactivation factor, suggesting that cryptic transcription produces the transcripts that then succumb to PPD. Remarkably, PPD inactivation has no effect on late transcripts at their proper time of expression. We show that this time-dependent PPD evasion by late transcripts requires the host factor NRDE2, which has previously been reported to protect cellular RNAs by sequestering decay factors. From these studies, we conclude that KSHV uses PPD to fine-tune the temporal expression of its genes by preventing their premature accumulation. ImportanceKaposis sarcoma-associated herpesvirus (KSHV) is an oncogenic gammaherpesvirus that causes Kaposis sarcoma and other lymphoproliferative disorders. Nuclear expression of KSHV genes results in exposure to at least two host-mediated nuclear RNA decay pathways, PABPN1 and PAP/{gamma}-mediated RNA decay (PPD) and an ARS2-mediated decay pathway. Perhaps unsurprisingly, we previously found that KSHV uses specific mechanisms to protect its transcripts from ARS2-mediated decay. In contrast, here we show that PPD is required to dampen the expression of viral late transcripts that are prematurely transcribed, presumably due to cryptic transcription early in infection. At the proper time for their expression, KSHV late transcripts evade PPD through the activity of the host factor NRDE2. We conclude that KSHV fine-tunes the temporal expression of its genes by modulating PPD activity. Thus, the virus both protects from and exploits the host nuclear RNA decay machinery for proper expression of its genes.

microbiology↗

bioRxiv2018

In silico identification of GPI-anchored proteins in Paracoccidioides

Glycosylphosphatidylinositol-anchored proteins (GPI-proteins) are widely found in eukaryotic organisms. In fungi, GPI-proteins are thought to be involved in diverse cellular mechanisms such as cell wall biosynthesis and cell wall remodeling, adhesion, antigenicity, and virulence. The conserved structural domains of GPI-protein allow the utilization of in silico prediction approach to identify this class of proteins using a genome-wide analysis. We used different previously characterized algorithms to search for genes that encode predicted GPI-proteins in the genome of P. brasiliensis and P. lutzii, thermal dimorphic fungi that causes paracoccidioidomycosis (PCM). By using these methods, 98 GPI-proteins were found in P. brasiliensis with orthologs in P. lutzii. A series of 28 GPI-proteins were classified in functional categories (such as glycoside hydrolases, chitin-processing proteins, and proteins involved in the biogenesis of the cell wall). Furthermore, 70 GPI-proteins exhibited homology with hypothetical conserved proteins of unknown function. These data will be an important resource for the future analysis of GPI-proteins in Paracoccidioides spp.

microbiology↗