Biology subjects

Aguilar, F.

Publications and source records attributed to Aguilar, F..

3 recordsLinked to original sources

bioRxiv2023

A Rationally Designed Antimicrobial Peptide from Structural and Functional Insight of Clostridium difficile Translation Initiation Factor 1

A significant increase of hospital-acquired bacterial infections during the COVID-19 pandemic has become an urgent medical problem. Clostridioides difficile is an urgent antibiotic-resistant bacterial pathogen and a leading causative agent of nosocomial infections. The increasing recurrence of C. difficile infection and antibiotic resistance in C. difficile has led to an unmet need for discovery of new compounds distinctly different from present antimicrobials, while antimicrobial peptides as promising alternatives to conventional antibiotics have attracted growing interest recently. Protein synthesis is an essential metabolic process in all bacteria and a validated antibiotic target. Initiation factor 1 from C. difficile (Cd-IF1) is the smallest of the three initiation factors that acts to establish the 30S initiation complex to initiate translation during protein biosynthesis. Here we report the solution NMR structure of Cd-IF1 which adopts a typical {beta}-barrel fold and consists of a five-stranded {beta}-sheet and one short -helix arranged in the sequential order {beta}1-{beta}2-{beta}3-1-{beta}4-{beta}5. The interaction of Cd-IF1 with the 30S ribosomal subunit was studied by NMR titration for the construction of a structural model of Cd-IF1 binding with the 30S subunit. The short -helix in IF1 was found to be critical for IF1 ribosomal binding. A peptide derived from this -helix was tested and displayed a high ability to inhibit the growth of C. difficile and other bacterial strains. These results provide a clue for rational design of new antimicrobials.

biochemistry↗

bioRxiv2022

Discovery of diverse human BH3-only and non-native peptide binders of pro-apoptotic BAK indicate that activators and inhibitors use asimilar binding mode and are not distinguished by binding affinity or kinetics

Apoptosis is a programmed form of cell death important for the development and maintenance of tissue homeostasis. The BCL-2 protein family controls key steps in apoptosis, dysregulation of which can lead to a wide range of human diseases. BCL-2 proteins comprise three groups: anti-apoptotic proteins, pro-apoptotic proteins, and BH3-only proteins. BAK is one of two pro-apoptotic proteins, and previous work has shown that binding of certain BH3-only proteins such as truncated BID (tBID), BIM, or PUMA to BAK leads to mitochondrial outer membrane permeabilization, the release of cytochrome c, and ultimately cell death. This process, referred to as activation, involves the BH3-stimulated conversion of BAK from monomer to dimer and then to oligomers that promote membrane disruption. Crystal structures of putative intermediates in this pathway, crosslinking data, and in vitro functional tests have provided insights into the activation event, yet the sequence-function relationships that make some but not all BH3-only proteins function as activators remain largely unexamined. In this work, we used computational protein design, yeast surface-display screening of candidate BH3-like peptides, and structure-based energy scoring to identify ten new binders of BAK that span a large sequence space. Among the new binders are two peptides from human proteins BNIP5 and PXT1 that promote BAK activation in liposome assays and induce cytochrome-c release from mitochondria, expanding current views of how BAK-mediated cell death may be triggered in cells. High-resolution crystal structures and binding experiments revealed a high degree of similarity in binding geometry, affinity, and association kinetics between peptide activators and inhibitors, including peptides described previously and those identified in this work. We propose a model for BAK activation that is based on differential engagement of BAK monomers vs. the BAK activation transition state that integrates our observations with previous reports of BAK binders, activators, and inhibitors.

biochemistry↗

bioRxiv2021

Passive epidemiological surveillance in wildlife in Costa Rica identifies pathogens of zoonotic and conservation importance

Epidemiological surveillance systems for pathogens in wild species have been proposed as a preventive measure for epidemic events. These systems can minimize the detrimental effects of an outbreak, but most importantly, passive surveillance systems are the best adapted to countries with limited resources. Therefore, the present study aims to evaluate the technical and infrastructural feasibility to establish this type of scheme in Costa Rica targeting thedetection of pathogens of zoonotic and conservation importance in wildlife. Between 2018 and 2020, 85 carcasses of free-ranging vertebrates were admitted for post mortem analysis and complementary laboratory analysis, representing a solid basis for the implementation of a passive surveillance system for wildlife diseases in the country. However, we encounter during this research significant constraints that affected the availability of carcasses for analysis, mainly related to the initial identification of cases, detection biases towards events in populated- or easily accessible-areas with nearby located wildlife management centers, further associated with financial disincentives, and limited local logistics capacity. Thus resulting in the exclusion of some geographic regions of the country. This epidemiological surveillance scheme allowed us to estimate the general state of health of the countrys wildlife, establishing the cause of death of the analyzed animals as follows: (i) 46 (54.1%) traumatic events, (ii) 23 (27.1%) infectious agents, (iii) two (2.4%) degenerative illness, (iv) three (3.5%) presumably poisoning, and (v) in 11 (12.9%)undetermined. It also allowed the detection of pathogens such as, canine distemper virus, Klebsiella pneumoniae, Toxoplasma gondii, Trypanosoma spp., Angiostrongylus spp., Dirofilaria spp., Baylisascaris spp., among others. As well as recognizing the circulation of these pathogens around national territory and also on those analyzed species. This strategy is crucial in geographical regions defined as critical for the appearance of diseases due to their great biodiversity and social conditions.

pathology↗