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ACS Infectious Diseases Feb 2024is a commensal of the human upper respiratory tract that can infect diverse host niches due, at least in part, to its ability to withstand both endogenous and...
is a commensal of the human upper respiratory tract that can infect diverse host niches due, at least in part, to its ability to withstand both endogenous and host-mediated oxidative stresses. Here, we show that , a gene previously linked to iron import, is essential for manganese recruitment the HfeBCD transporter. Structural analyses show that metal binding in HfeA uses a unique mechanism that involves substantial rotation of the C-terminal lobe of the protein. Disruption of reduced manganese acquisition and was associated with decreased growth under aerobic conditions, impaired manganese-superoxide dismutase activity, reduced survival in macrophages, and changes in biofilm production in the presence of superoxide. Collectively, this work shows that HfeA contributes to manganese acquisition and virulence attributes. High conservation of the permease in species suggests that it may serve similar roles in other pathogenic Pasteurellaceae.
Topics: Humans; Haemophilus influenzae; Membrane Transport Proteins; Manganese; Biofilms; Homeostasis
PubMed: 38240689
DOI: 10.1021/acsinfecdis.3c00407 -
Biomolecules Nov 2022The transmembrane transport of weak acid and base metabolites depends on the local pH conditions that affect the protonation status of the substrates and the... (Review)
Review
The transmembrane transport of weak acid and base metabolites depends on the local pH conditions that affect the protonation status of the substrates and the availability of co-substrates, typically protons. Different protein designs ensure the attraction of substrates and co-substrates to the transporter entry sites. These include electrostatic surface charges on the transport proteins and complexation with seemingly transport-unrelated proteins that provide substrate and/or proton antenna, or enzymatically generate substrates in place. Such protein assemblies affect transport rates and directionality. The lipid membrane surface also collects and transfers protons. The complexity in the various systems enables adjustability and regulation in a given physiological or pathophysiological situation. This review describes experimentally shown principles in the attraction and facilitation of weak acid and base transport substrates, including monocarboxylates, ammonium, bicarbonate, and arsenite, plus protons as a co-substrate.
Topics: Protons; Biological Transport; Membrane Transport Proteins; Hydrogen-Ion Concentration
PubMed: 36551222
DOI: 10.3390/biom12121794 -
Current Opinion in Biotechnology Apr 2022Biological membranes are inherently complex, making transport processes in microbial cell factories a significant bottleneck. Lack of knowledge on transport proteins'... (Review)
Review
Biological membranes are inherently complex, making transport processes in microbial cell factories a significant bottleneck. Lack of knowledge on transport proteins' characteristics and the need for advanced technical equipment often hamper transporter identification and optimization. For these reasons, moving away from individual characterization and towards high-throughput mining, engineering, and screening of transporters is an increasingly attractive approach. Superior transporters can be selected from large libraries by coupling their activity to growth, for substrates that function as feedstocks or toxic compounds. Other compounds can be screened thanks to recent advances in the design and deployment of synthetic genetic circuits (biosensors). Furthermore, novel strategies are rapidly increasing the repertoire of biomolecule transporters susceptible to high-throughput selection methods.
Topics: Biological Transport; Biosensing Techniques; High-Throughput Screening Assays; Membrane Transport Proteins; Metabolic Engineering
PubMed: 34968868
DOI: 10.1016/j.copbio.2021.11.012 -
Nature Structural & Molecular Biology Dec 2023Over half of mitochondrial proteins are imported from the cytosol via the pre-sequence pathway, controlled by the TOM complex in the outer membrane and the TIM23 complex...
Over half of mitochondrial proteins are imported from the cytosol via the pre-sequence pathway, controlled by the TOM complex in the outer membrane and the TIM23 complex in the inner membrane. The mechanisms through which proteins are translocated via the TOM and TIM23 complexes remain unclear. Here we report the assembly of the active TOM-TIM23 supercomplex of Saccharomyces cerevisiae with translocating polypeptide substrates. Electron cryo-microscopy analyses reveal that the polypeptide substrates pass the TOM complex through the center of a Tom40 subunit, interacting with a glutamine-rich region. Structural and biochemical analyses show that the TIM23 complex contains a heterotrimer of the subunits Tim23, Tim17 and Mgr2. The polypeptide substrates are shielded from lipids by Mgr2 and Tim17, which creates a translocation pathway characterized by a negatively charged entrance and a central hydrophobic region. These findings reveal an unexpected pre-sequence pathway through the TOM-TIM23 supercomplex spanning the double membranes of mitochondria.
Topics: Membrane Transport Proteins; Mitochondrial Precursor Protein Import Complex Proteins; Carrier Proteins; Mitochondrial Membrane Transport Proteins; Saccharomyces cerevisiae Proteins; Protein Transport; Mitochondria; Saccharomyces cerevisiae; Mitochondrial Proteins; Peptides; Membrane Proteins
PubMed: 37696957
DOI: 10.1038/s41594-023-01103-7 -
Clinical Pharmacokinetics Feb 2022Cladribine is a nucleoside analog that is phosphorylated in its target cells (B and T-lymphocytes) to its active triphosphate form (2-chlorodeoxyadenosine triphosphate).... (Review)
Review
Cladribine is a nucleoside analog that is phosphorylated in its target cells (B and T-lymphocytes) to its active triphosphate form (2-chlorodeoxyadenosine triphosphate). Cladribine tablets 10 mg (Mavenclad), administered for up to 10 days per year in 2 consecutive years (3.5-mg/kg cumulative dose over 2 years), are used to treat patients with relapsing multiple sclerosis. Cladribine has been shown to be a substrate of various nucleoside transporters (NTs). Intestinal absorption and distribution of cladribine throughout the body appear to be essentially mediated by equilibrative NTs (ENTs) and concentrative NTs (CNTs), specifically by ENT1, ENT2, ENT4, CNT2 (low affinity), and CNT3. Other efficient transporters of cladribine are the ABC efflux transporters, specifically breast cancer resistance protein, which likely modulates the oral absorption and renal excretion of cladribine. A key transporter for the intracellular uptake of cladribine into B and T-lymphocytes is ENT1 with ancillary contributions of ENT2 and CNT2. Transporter-based drug interactions affecting absorption and target cellular uptake of a prodrug such as cladribine are likely to reduce systemic bioavailability and target cell exposure, thereby possibly hampering clinical efficacy. In order to manage optimized therapy, i.e., to ensure uncompromised target cell uptake to preserve the full therapeutic potential of cladribine, it is important that clinicians are aware of the existence of NT-inhibiting medicinal products, various lifestyle drugs, and food components. This article reviews the existing knowledge on inhibitors of NT, which may alter cladribine absorption, distribution, and uptake into target cells, thereby summarizing the existing knowledge on optimized methods of administration and concomitant drugs that should be avoided during cladribine treatment.
Topics: ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Cladribine; Drug Interactions; Equilibrative Nucleoside Transporter 1; Humans; Membrane Transport Proteins; Neoplasm Proteins; Nucleoside Transport Proteins
PubMed: 34894346
DOI: 10.1007/s40262-021-01089-9 -
Proceedings of the National Academy of... Jul 2022Bacterial pathogens acquire heme from the host hemoglobin as an iron nutrient for their virulence and proliferation in blood. Concurrently, they encounter cytotoxic-free...
Bacterial pathogens acquire heme from the host hemoglobin as an iron nutrient for their virulence and proliferation in blood. Concurrently, they encounter cytotoxic-free heme that escapes the heme-acquisition process. To overcome this toxicity, many gram-positive bacteria employ an ATP-binding cassette heme-dedicated efflux pump, HrtBA in the cytoplasmic membranes. Although genetic analyses have suggested that HrtBA expels heme from the bacterial membranes, the molecular mechanism of heme efflux remains elusive due to the lack of protein studies. Here, we show the biochemical properties and crystal structures of HrtBA, alone and in complex with heme or an ATP analog, and we reveal how HrtBA extracts heme from the membrane and releases it. HrtBA consists of two cytoplasmic HrtA ATPase subunits and two transmembrane HrtB permease subunits. A heme-binding site is formed in the HrtB dimer and is laterally accessible to heme in the outer leaflet of the membrane. The heme-binding site captures heme from the membrane using a glutamate residue of either subunit as an axial ligand and sequesters the heme within the rearranged transmembrane helix bundle. By ATP-driven HrtA dimerization, the heme-binding site is squeezed to extrude the bound heme. The mechanism sheds light on the detoxification of membrane-bound heme in this bacterium.
Topics: Adenosine Triphosphatases; Adenosine Triphosphate; Bacterial Proteins; Corynebacterium diphtheriae; Heme; Membrane Transport Proteins; Protein Conformation; Protein Multimerization
PubMed: 35767641
DOI: 10.1073/pnas.2123385119 -
Nature Structural & Molecular Biology Nov 2023Organic anion transporters (OATs) of the SLC22 family have crucial roles in the transport of organic anions, including metabolites and therapeutic drugs, and in...
Organic anion transporters (OATs) of the SLC22 family have crucial roles in the transport of organic anions, including metabolites and therapeutic drugs, and in transporter-mediated drug-drug interactions. In the kidneys, OATs facilitate the elimination of metabolic waste products and xenobiotics. However, their transport activities can lead to the accumulation of certain toxic compounds within cells, causing kidney damage. Moreover, OATs are important drug targets, because their inhibition modulates the elimination or retention of substrates linked to diseases. Despite extensive research on OATs, the molecular basis of their substrate and inhibitor binding remains poorly understood. Here we report the cryo-EM structures of rat OAT1 (also known as SLC22A6) and its complexes with para-aminohippuric acid and probenecid at 2.1, 2.8 and 2.9 Å resolution, respectively. Our findings reveal a highly conserved substrate binding mechanism for SLC22 transporters, wherein four aromatic residues form a cage to accommodate the polyspecific binding of diverse compounds.
Topics: Rats; Animals; Organic Anion Transport Protein 1; Cryoelectron Microscopy; Membrane Transport Proteins; Organic Anion Transporters; Kidney
PubMed: 37845412
DOI: 10.1038/s41594-023-01123-3 -
Chemical Society Reviews Apr 2023The great clinical success of cisplatin and its derivatives has convinced people that metal complexes could play a more significant role in human cancer therapy.... (Review)
Review
The great clinical success of cisplatin and its derivatives has convinced people that metal complexes could play a more significant role in human cancer therapy. However, targeting and drug resistance are still two dominant problems that need to be urgently solved for metallodrugs' efficacy and clinical translation. As an important component of metal complexes, organometallics have been experiencing rapid development in recent years. Compared with platinum drugs, emerging anti-tumor organometallics targeting dynamic bioprocesses provide an effective strategy to overcome conventional problems. This review focuses on burgeoning anti-tumor strategies and provides up-to-date advances in anti-tumor organometallics development based on their action mechanisms. Specifically, important tumor-overexpressed proteins and nucleic acids as organometallics' anti-tumor targets are systematically presented, followed by organometallics that exert their anti-tumor activity by perturbing tumor intracellular energy/redox/metal/immune homeostasis. Finally, nine cell death pathways including apoptosis, paraptosis, autophagy, oncosis, necrosis, necroptosis, ferroptosis, pyroptosis, and immunogenic cell death (ICD) that can be induced by organometallics are reviewed, and their morphological and biochemical features are summarised. This review at the interface of chemistry, biology, and medicine aims to enlighten the rational development of organometallic anti-tumor agents.
Topics: Antineoplastic Agents; Organometallic Compounds; Humans; Membrane Transport Proteins; Receptors, Cell Surface; Neoplasms; Homeostasis; Animals; Oxidation-Reduction; Cell Death
PubMed: 37014670
DOI: 10.1039/d2cs00757f -
International Journal of Molecular... Jul 2022Membrane transport proteins are widely present in all living organisms, however, their function, transported substrate, and mechanism of action are unknown. Here we use...
Membrane transport proteins are widely present in all living organisms, however, their function, transported substrate, and mechanism of action are unknown. Here we use diverse bioinformatics tools to investigate the evolution of MTPs, analyse domain organisation and loop topology, and study the comparative alignment of modelled 3D structures. Our results suggest a high level of conservancy between MTPs from different taxa on both amino acids and structural levels, which imply some degree of functional similarities. The presence of loop/s of different lengths in various positions suggests tax-on-specific adaptation to transported substrates, intracellular localisation, accessibility for post-translation modifications, and interaction with other proteins. The comparison of modelled structures proposes close relations and a common origin for MTP and Na/H exchanger. Further, a high level of amino acid similarity and identity between archaeal and bacterial MTPs and Na/H exchangers imply conservancy of ion transporting function at least for archaeal and bacterial MTPs.
Topics: Amino Acid Sequence; Biological Transport; Ion Transport; Membrane Transport Proteins; Sodium-Hydrogen Exchangers
PubMed: 35897663
DOI: 10.3390/ijms23158094 -
Biomolecules Dec 2020The translocases of the mitochondrial outer and inner membranes, the TOM and TIMs, import hundreds of nucleus-encoded proteins into mitochondria. TOM and TIMs are... (Review)
Review
The translocases of the mitochondrial outer and inner membranes, the TOM and TIMs, import hundreds of nucleus-encoded proteins into mitochondria. TOM and TIMs are multi-subunit protein complexes that work in cooperation with other complexes to import proteins in different sub-mitochondrial destinations. The overall architecture of these protein complexes is conserved among yeast/fungi, animals, and plants. Recent studies have revealed unique characteristics of this machinery, particularly in the eukaryotic supergroup Excavata. Despite multiple differences, homologues of Tim17, an essential component of one of the TIM complexes and a member of the Tim17/Tim22/Tim23 family, have been found in all eukaryotes. Here, we review the structure and function of Tim17 and Tim17-containing protein complexes in different eukaryotes, and then compare them to the single homologue of this protein found in , a unicellular parasitic protozoan.
Topics: Animals; Cell Nucleus; Conserved Sequence; Fungi; Gene Expression; Humans; Membrane Transport Proteins; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Precursor Protein Import Complex Proteins; Mitochondrial Proteins; Multiprotein Complexes; Plants; Protein Binding; Protein Structure, Secondary; Protein Transport; Trypanosoma brucei brucei
PubMed: 33297490
DOI: 10.3390/biom10121643