In health, commensal bacteria from oral biofilms stimulate polymorphonuclear neutrophil (PMN) recruitment in gingival sulci and the oral cavity. Oral PMN (oPMN) is short-lived cells with low prosurvival gene expression. In periodontitis, oPMN accumulates in higher numbers, has extended lifespan, and sustains nonresolving inflammation. We hypothesize that short- and long-chain free fatty acids (SCFAs and LCFAs) and lipid mediator resolvin E1 (RvE1) modulate host ability to control biofilms and resolve inflammation. Our objective was to measure oPMN surface expression of receptors FFAR2 (binds bacteria-derived SCFA), FFAR4 (binds LCFA, EPA, and DHA), and ERV1 (binds RvE1) in health and to assess sex differences. We included 20 periodontally healthy individuals aged 20-80 years (10 males, 10 females), who were asked to (1) answer a targeted health nutritional questionnaire and (2) provide an oral saline rinse. oPMN isolated by sequential filtration was labeled with fluorophore-conjugated antibodies against CD11b, CD14, CD16, CD66b, ERV1, FFAR2, and FFAR4 and analyzed by flow cytometry. Statistical analyses were the following: two-way ANOVA, Tukey's test, and Pearson's correlation. Oral rinses contained 80% oPMN of which 60% were ERV1+ and FFAR2+, and 10% FFAR4+, with no sex differences. Females had more oPMN ERV1 compared to males. Both sexes had higher ERV1 compared to FFAR2 and FFAR4. CD66b+CD16high oPMN expressed less ERV1 and FFAR2 compared to CD66b+CD16low. There were positive correlations between oPMN ERV1 and FFAR2 expression and between ERV1+ and FFAR2+ oPMN and fish intake. These findings will help to better understand how oral host and microbiome interactions maintain periodontal health.

• Publication type
• Journal Article MeSH

Sulfhydryl oxidase Erv1 is a ubiquitous and conserved protein of the mitochondrial intermembrane space that plays a role in the transport of small sulfur-containing proteins. In higher eukaryotes, Erv1 interacts with the mitochondrial import protein Mia40. However, Trypanosoma brucei lacks an obvious Mia40 homologue in its genome. Here we show by tandem affinity purification and mass spectrometry that in this excavate protist, Erv1 functions without a Mia40 homologue and most likely any other interaction partner. Down-regulation of TbErv1 caused a reduction of the mitochondrial membrane potential already within 24h to less than 50% when compared with control cells. The depletion of TbErv1 was accompanied by accumulation of trCOIV precursor, with a concomitant reduction of aconitase activity both in the cytosol and mitochondrion. Overall, TbErv1 seems to have a role in the mitochondrial translocation and Fe-S cluster assembly in the organelle.

• MeSH
• Mass Spectrometry MeSH
• Protein Interaction Mapping MeSH
• Mitochondria enzymology   metabolism   MeSH
• Oxidoreductases metabolism   MeSH
• Iron-Sulfur Proteins metabolism   MeSH
• Protozoan Proteins metabolism   MeSH
• Trypanosoma brucei brucei enzymology   metabolism   MeSH
• Protein Binding MeSH
• Publication type
• Journal Article MeSH

In yeast (Saccharomyces cerevisiae) and animals, the sulfhydryl oxidase Erv1 functions with Mia40 in the import and oxidative folding of numerous cysteine-rich proteins in the mitochondrial intermembrane space (IMS). Erv1 is also required for Fe-S cluster assembly in the cytosol, which uses at least one mitochondrially derived precursor. Here, we characterize an essential Erv1 orthologue from the protist Trypanosoma brucei (TbERV1), which naturally lacks a Mia40 homolog. We report kinetic parameters for physiologically relevant oxidants cytochrome c and O(2), unexpectedly find O(2) and cytochrome c are reduced simultaneously, and demonstrate that efficient reduction of O(2) by TbERV1 is not dependent upon a simple O(2) channel defined by conserved histidine and tyrosine residues. Massive mitochondrial swelling following TbERV1 RNA interference (RNAi) provides evidence that trypanosome Erv1 functions in IMS protein import despite the natural absence of the key player in the yeast and animal import pathways, Mia40. This suggests significant evolutionary divergence from a recently established paradigm in mitochondrial cell biology. Phylogenomic profiling of genes also points to a conserved role for TbERV1 in cytosolic Fe-S cluster assembly. Conversely, loss of genes implicated in precursor delivery for cytosolic Fe-S assembly in Entamoeba, Trichomonas, and Giardia suggests fundamental differences in intracellular trafficking pathways for activated iron or sulfur species in anaerobic versus aerobic eukaryotes.

• MeSH
• Cytochromes c chemistry   MeSH
• Phylogeny MeSH
• Gene Knockdown Techniques MeSH
• Kinetics MeSH
• Oxygen chemistry   MeSH
• Mitochondrial Proteins chemistry   genetics   MeSH
• Mitochondria enzymology   ultrastructure   MeSH
• Evolution, Molecular MeSH
• Mutagenesis, Site-Directed MeSH
• Oxidation-Reduction MeSH
• Oxidants MeSH
• Oxidoreductases chemistry   genetics   MeSH
• Protozoan Proteins chemistry   genetics   MeSH
• RNA Interference MeSH
• Protein Folding MeSH
• Amino Acid Substitution MeSH
• Protein Transport MeSH
• Trypanosoma brucei brucei cytology   enzymology   MeSH
• Mitochondrial Swelling MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

A single mitochondrial network in the cell undergoes constant fission and fusion primarily depending on the local GTP gradients and the mitochondrial energetics. Here we overview the main properties and regulation of pro-fusion and pro-fission mitodynamins, i.e. dynamins-related GTPases responsible for mitochondrial shape-forming, such as pro-fusion mitofusins MFN1, MFN2, and the inner membrane-residing long OPA1 isoforms, and pro-fission mitodynamins FIS1, MFF, and DRP1 multimers required for scission. Notably, the OPA1 cleavage into non-functional short isoforms at a diminished ATP level (collapsed membrane potential) and the DRP1 recruitment upon phosphorylation by various kinases are overviewed. Possible responses of mitodynamins to the oxidative stress, hypoxia, and concomitant mtDNA mutations are also discussed. We hypothesize that the increased GTP formation within the Krebs cycle followed by the GTP export via the ADP/ATP carrier shift the balance between fission and fusion towards fusion by activating the GTPase domain of OPA1 located in the peripheral intermembrane space (PIMS). Since the protein milieu of PIMS is kept at the prevailing oxidized redox potential by the TOM, MIA40 and ALR/Erv1 import-redox trapping system, redox regulations shift the protein environment of PIMS to a more reduced state due to the higher substrate load and increased respiration. A higher cytochrome c turnover rate may prevent electron transfer from ALR/Erv1 to cytochrome c. Nevertheless, the putative links between the mitodynamin responses, mitochondrial morphology and the changes in the mitochondrial bioenergetics, superoxide production, and hypoxia are yet to be elucidated, including the precise basis for signaling by the mitochondrion-derived vesicles.

• MeSH
• Models, Biological MeSH
• Cell Hypoxia physiology   MeSH
• Humans MeSH
• DNA, Mitochondrial physiology   genetics   MeSH
• Mitochondria metabolism   MeSH
• Oxidation-Reduction MeSH
• Oxidative Stress physiology   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH