Biology subjects

Guerra, P.

Publications and source records attributed to Guerra, P..

4 recordsLinked to original sources

bioRxiv2024

Whole genome sequence and 16S rRNA gene amplicon metagenomics of enhanced in-situ reductive dechlorination at a tetrachloroethene-contaminated superfund site

The application of environmental DNA analysis techniques to guide the bioremediation strategy for tetrachloroethene-contaminated groundwater is exemplified by the North Railroad Avenue Plume (NRAP) Superfund site located in New Mexico, USA. Enhanced reductive dechlorination (ERD) was selected as the remedy due to the presence of tetrachloroethene biodegradation byproducts, organohalide respiring genera Dehalococcoides and Dehalobacter, and associated reductive dehalogenase genes detected prior to remediation. DNA extracted from groundwater samples collected prior to remedy application and after four, 23 and 39 months was subjected to 16SrRNA gene amplicon and whole genome sequencing (WGS). The goals were to compare the potential of these methods as tools for environmental engineers and to highlight how advancements in DNA techniques can be used to understand ERD. The response of the indigenous NRAP microbiome to the injection and recirculation of electron donors and hydrogen sources is consistent with results obtained from microcosms, dechlorinating consortia, and other contaminated sites. WGS detects three times as many phyla and six times as many genera as 16S rRNA gene amplicons. Both techniques reveal abundance changes in Dehalococcoides and Dehalobacter that reflect organohalide form and availability. No methane was detected before remediation, its appearance after biostimulation corresponds to the increase in methanogenic Archaea. Assembly of WGS reads produced scaffolds containing reductive dehalogenase genes from Dehalococcoides, Dehalobacter, Dehalogenimonas, Desulfocarbo, and Desulfobacula. Anaerobic and aerobic cometabolic organohalide degrading microbes that increase in abundance at NRAP include methanogenic Archaea, methanotrophs, Dechloromonas, and Xanthobacter, some of which contain hydrolytic dehalogenase genes. Aerobic cometabolism may be supported by oxygen gradients existing at the aquifer-soil interface or by microbes that have the potential to produce O2 via chlorite dismutation. Results from next-generation sequencing-based methods are consistent with current hypotheses regarding syntrophy in environmental microbiomes and reveals novel taxa and genes that may contribute to ERD.

genomics↗

bioRxiv2022

A synthetic genetic array screen for interactions with the RNA helicase DED1 during cell stress in budding yeast

During cellular stress it is essential for cells to alter their gene expression to adapt and survive. Gene expression is regulated at multiple levels, but translation regulation is both a method for rapid changes to the proteome and, as one of the most energy-intensive cellular processes, a way to efficiently re-direct cellular resources during stress conditions. Despite this ideal positioning, many of the specifics of how translation is regulated, positively or negatively, during various types of cellular stress remain poorly understood. To further assess this regulation, we examined the essential translation factor Ded1, an RNA helicase that has been previously shown to play important roles in the translational response to cellular stress. In particular, ded1 mutants display an increased resistance to growth inhibition and translation repression induced by the TOR pathway inhibitor, rapamycin, suggesting that normal stress responses are partially defective in these mutants. To gain further insight into Ded1 translational regulation during stress, synthetic genetic array analysis was conducted in the presence of rapamycin with a ded1 mutant and a library of non-essential genes in S. cerevisiae to identify positive and negative genetic interactions in an unbiased manner. Here we report the results of this screen and subsequent network mapping and GO-term analysis. Hundreds of candidate interactions were identified, which fell into expected categories, such as ribosomal proteins and amino acid biosynthesis, as well as unexpected ones, including membrane trafficking, sporulation, and protein glycosylation. Therefore, these results provide several specific directions for further comprehensive studies.

genetics↗

bioRxiv2021

Vacuolar localization via the N-terminal domain of Sch9 is required for TORC1-dependent phosphorylation and downstream signal transduction

The budding yeast Sch9 kinase (functional ortholog of the mammalian S6 kinase) is a major effector of the Target of Rapamycin Complex 1 (TORC1) complex in the regulation of cell growth in response to nutrient availability and stress. In budding yeast, Sch9 is partially localized at the vacuolar surface, where it is phosphorylated by TORC1 under favorable growth conditions. Sch9 recruitment at the vacuole is mediated by direct interaction between PI(3,5)P2 on the vacuolar membrane and the region of Sch9 encompassing amino acid residues 1-390, which contains a C2 domain. Since many C2 domains mediate phospholipid binding, it had been suggested that the C2 domain of Sch9 mediates its vacuolar recruitment. However, the in vivo requirement of the C2 domain for Sch9 localization had not been demonstrated, and the phenotypic consequences of Sch9 delocalization remained unknown. Here, by examining cellular localization, phosphorylation state and growth phenotypes of Sch9 truncation mutants, we show that deletion of the N-terminal domain of Sch9 (aa 1-182), but not the C2 domain (aa 183-399), impairs vacuolar localization and TORC1-dependent phosphorylation of Sch9, while causing growth defects similar those observed in sch9{Delta} cells. Artificial tethering of an N-terminally truncated Sch9 mutant at the vacuolar membrane rescued TORC1-dependent phosphorylation and cell growth. Our study uncovers a key role for the N-terminal domain of Sch9 and demonstrates that recruitment of Sch9 at the vacuolar surface is necessary for TORC1-dependent phosphorylation and downstream signal transduction for the regulation of cell growth.

cell biology↗

bioRxiv2021

TORC1 and PKA activity towards ribosome biogenesis oscillates in synchrony with the budding yeast cell cycle

Recent studies have revealed that the growth rate of budding yeast and mammalian cells varies during the cell cycle. By linking a multitude of signals to cell growth, the highly conserved Target of Rapamycin Complex 1 (TORC1) and Protein Kinase A (PKA) pathways are prime candidates for mediating the dynamic coupling between growth and division. However, measurements of TORC1 and PKA activity during the cell cycle are still lacking. Following the localization dynamics of two TORC1 and PKA targets via time-lapse microscopy in hundreds of yeast cells, we found that the activity of these pathways towards ribosome biogenesis fluctuates in synchrony with the cell cycle even under constant external conditions. Mutations of upstream TORC1 and PKA regulators suggested that internal metabolic signals partially mediate these activity changes. Our study reveals a new aspect of TORC1 and PKA signaling, which will be important for understanding growth regulation during the cell cycle.

systems biology↗