Biology subjects

Karas, P.

Publications and source records attributed to Karas, P..

3 recordsLinked to original sources

bioRxiv2024

Isolation of a novel Sphingomonas strain able to degrade the pleuromutilin tiamulin: omic analysis reveals its transformation pathway

Tiamulin (TIA) is a commonly used veterinary antibiotic, persistent in the animal digestive system and downstream receiving environments like soil after manuring. We aimed to isolate and characterize TIA-degrading bacteria for bioaugmentation strategies towards mitigating TIA environmental pressure. A strain able to degrade TIA and use it as sole C source was isolated from a soil exhibiting enhanced biodegradation of the antibiotic. The isolate degraded TIA at concentrations up to 100 {micro}g ml-1, with pH and temperature optima of 6.5-7.5 and 16-25{degrees}C respectively. Phylogenomic analysis deemed the isolate to be a new Sphingomonas species (83.87 % ANI with S. laterariae, [≤] 95 %), which was named Candidatus Sphingomonas perruchonii. Genomics and transcriptomics revealed the TIA-driven induction of features conducive with its antiotrophic character; genes encoding for drug efflux pumps and the catabolism of xenobiotics. These included ribosome protective ABC-F transporters and efflux pumps able to protect the ribosome and microbial cells from TIA, oxygenases (e.g. P450 cytochrome) and hydrolases (e.g. alpha/beta hydrolases and amidohydrolases) possibly contributing to its degradation. LC-MS/MS analysis detected putative transformation products (TPs) of TIA, leading us to propose a transformation pathway. This involved a primary oxidation of the tricyclic moiety of TIA to a mono-hydroxylated derivative (TIA-O), potentially mediated by the highly upregulated monoxygenases, which was either further oxidized to TIA-O2 or hydrolysed, by the upregulated hydrolase or amidohydrolases, to 2-diethylamino-ethyl-thio acetic acid, both not degrading further. Further tests and in vitro functional analysis will verify the role of these genes in the transformation of TIA. IMPORTANCEAnthropogenic antibiotic pressure in environmental settings has been acknowledged as a major threat for the public health and the environment, through the: (i) associated ecotoxicological impact; and (ii) the increase of antibiotic resistance dispersal among non-pathogenic and pathogenic bacteria, restricting available choices for treating infections in health care. In situ microbial biotransformation of antibiotics and eventual removal is an environmentally friendly method currently under intense investigation, which was recently proposed for the reduction of antibiotic selective pressure. The present study provides mechanistic insights on the genomic constituents of antibiotrophy, namely, the tolerance against and the biodegradation/transformation of the antibiotic in question. We characterize the capacity of a bacterial isolate to transform tiamulin, a heavily used antibiotic in pig farming, and propose associated biotransformation mechanisms, through an integrated approach of standard microbiological methods combined with and multi-omics (genomics, transcriptomics, metabolomics).

genomics↗

bioRxiv2023

Endocisternal interfaces for minimally invasive neural stimulation and recording of the brain and spinal cord

Minimally invasive neural interfaces can be used to diagnose, manage, and treat many disorders with substantially reduced risks of surgical complications. Endovascular neural interfaces implanted in the veins or arteries is one approach, but it requires prescriptions of anti-thrombotic medication and are likely not explantable after endothelialization. More critically, the approach is limited by the small size and location of blood vessels, such that many important cortical, subcortical, spinal targets cannot be reached. Here, we demonstrate a chronic endocisternal neural interface that approaches brain and spinal cord targets through inner and outer cerebral spinal fluid (CSF) spaces. These spaces surround the nervous system and lack the tortuosity of the circulatory system, giving us access to the entire brain convexity, deep brain structures within the ventricles, and the spinal cord from the spinal subarachnoid space. Combined with miniature magnetoelectric-powered bioelectronics, the entire wireless system is deployable through a percutaneous procedure. The flexible catheter electrodes can be freely navigated throughout the body from the spinal to cranial subarachnoid space, and from the cranial subarachnoid space to the ventricles. We show in a large animal model that we can also reposition the recording and stimulation electrodes or explant the neural interface after chronic implantation. This enables applications in therapies that require transient or permanent brain/machine interface such as stroke rehabilitation and epilepsy monitoring and opens a new class of minimally invasive endocisternal bioelectronics.

bioengineering↗

bioRxiv2023

Evolution towards simplicity in bacterial small heat shock protein system

Evolution can tinker with multi-protein machines and replace them with simpler single-protein systems performing equivalent functions in equally efficient manner. It is unclear how, on a molecular level, such simplification can arise. With ancestral reconstruction and biochemical analysis we have traced the evolution of bacterial small heat shock proteins (sHsp), which help to refold proteins from aggregates using either two proteins with different functions (IbpA and IbpB) or a secondarily single sHsp that performs both functions in an equally efficient way. Secondarily single sHsp evolved from IbpA, an ancestor specialized in strong substrate binding. Evolution of an intermolecular binding site drove the alteration of substrate binding properties, as well as formation of higher-order oligomers. Upon two mutations in the -crystallin domain, secondarily single sHsp interacts with aggregated substrates less tightly. Paradoxically, less efficient binding positively influences the ability of sHsp to stimulate substrate refolding, since the dissociation of sHps from aggregates is required to initiate Hsp70-Hsp100-dependent substrate refolding. After the loss of a partner, IbpA took over its role in facilitating the sHsp dissociation from an aggregate by weakening the interaction with the substrate, which became beneficial for the refolding process. We show that the same two amino acids introduced in modern-day system define whether the IbpA acts as a single sHsp or obligatorily cooperates with an IbpB partner. Our discoveries illuminate how one sequence has evolved to encode functions previously performed by two distinct proteins.

biochemistry↗