Biology subjects

Catarino, T.

Publications and source records attributed to Catarino, T..

3 recordsLinked to original sources

bioRxiv2024

Flavin-containing siderophore-interacting protein of Shewanella putrefaciens DSM 9451 reveals substrate specificity in ferric-siderophore reduction

Shewanella are bacteria widespread in marine and brackish water environments and emergent opportunistic pathogens. Their environmental versatility is highly dependent on the ability to produce an abundance of iron-rich proteins, mainly multiheme c-type cytochromes. Although iron plays a vital role in the ability of Shewanella species to survive in various environments, very few studies exist regarding the strategies by which these bacteria scavenge iron from the environment. Small molecule siderophore-mediated iron transport is a strategy commonly employed for iron acquisition, and it was identified amongst Shewanella spp. over two decades ago. Shewanella species produce hydroxamate-type siderophores and iron removal from these compounds can occur in the cytoplasm via Fe(III)-siderophore reduction mediated by siderophore-interacting proteins (SIPs). The genome of Shewanella putrefaciens DSM 9451 isolated from an infected child contains representatives of the two different cytosolic families of SIPs: the flavin-containing siderophore interacting protein family (SIP) and the iron-sulfur cluster-containing ferric siderophore reductase family (FSR). Here, we report the expression and purification of the flavin-containing (SbSIP) and iron-sulfur cluster-containing (SbFSR) Fe(III)-siderophore reductases of Shewanella putrefaciens DSM 9451. The structural and functional characterization of SbSIP shows distinct features from the highly homologous SIP from Shewanella frigidimarina (SfSIP). These include significant structural differences, different binding affinities for NADH and NADPH, and lower rates of Fe(III)-siderophore reduction, results which consolidate in the putative identification of the binding pocket for these proteins. Overall our work highlights NADH and NADPH specificity and the different Fe(III)- siderophore reduction abilities of the SIP family suggesting a tailoring of these enzymes towards meeting different microbial iron requirements.

biochemistry↗

bioRxiv2023

The structure of a novel ferredoxin: FhuF, a ferric-siderophore reductase from E. coli K-12 with a novel 2Fe-2S cluster coordination

Iron is a vital element for life. However, after the Great Oxidation Event, the bioavailability of this element became limited. To overcome iron shortage and to scavenge this essential nutrient, microorganisms use siderophores, secondary metabolites that have some of the highest affinities for ferric iron. The crucial step of iron release from these compounds to be subsequently integrated into cellular components is mediated by Siderophore-Interacting Proteins (SIPs) or Ferric-siderophore reductases (FSRs). In this work, we report the structure of an FSR for the first time. FhuF from laboratory strain Escherichia coli K-12 is the archetypical FSR, known for its atypical 2Fe-2S cluster with the binding motif C-C-X10-C-X2-C. The 1.9 [A] resolution crystallographic structure of FhuF shows it to be the only 2Fe-2S protein known to date with two consecutive cysteines binding different Fe atoms. This novel coordination provides a rationale for the unusual spectroscopic properties of FhuF. Furthermore, FhuF shows an impressive ability to reduce hydroxamate-type siderophores at very high rates when compared to flavin-based SIPs, but like SIPs it appears to use the redox-Bohr effect to achieve catalytic efficiency. Overall, this work closes the knowledge gap regarding the structural properties of ferric-siderophore reductases and simultaneously opens the door for further understanding of the diverse mechanistic abilities of these proteins in the siderophore recycling pathway.

biochemistry↗

bioRxiv2020

Constitutive ghrelin receptor activity modulates AMPA receptor traffic and supports memory formation

The ability of animals to store and retrieve food caches in the wild requires the integration of biological signals of hunger, satiety and memory. The role of ghrelin in regulating feeding and memory makes ghrelin receptors an important target to shape the required cellular and molecular responses. We investigated the effects of the high ligand-independent activity of the ghrelin receptor on the physiology of excitatory synapses. Blocking this type of activity produced a decrease in the synaptic content of AMPA receptors in hippocampal neurons and a reduction in GluA1 phosphorylation at Ser845. Impaired constitutive activity from the ghrelin receptor increased surface diffusion of AMPA receptors and impaired AMPA receptor synaptic delivery mediated by chemical long-term potentiation. These observations support a role for the constitutive activity of the ghrelin receptor in regulating AMPA receptor trafficking under basal conditions and synaptic plasticity. Accordingly, we found that blocking the ghrelin receptor constitutive activity impairs spatial and recognition memory. Impact statementThis work uncovers a role for the constitutive activity of the ghrelin receptor in memory, and in the regulation of the synaptic levels of AMPA receptors, their mobility and synaptic plasticity. Underscoring the importance of deciphering the physiological role of constitutive ghrelin receptor activity, ghrelin receptor inverse agonism is now being considered as a therapy to treat alcohol use disorder.

neuroscience↗