bims-cytox1 Biomed News
on Cytochrome oxidase subunit 1
Issue of 2026–06–14
two papers selected by
Gavin McStay, Liverpool John Moores University
  1. Copper transport to mitochondria by SLC25A3 contributes to skeletal myoblast differentiation and is required for survival of differentiated myotubes.
  2. Structure determination and dual targeting of a plant TACO1 identifies its ancient role as an organelle translation regulator.
  1. bioRxiv. 2026 Jun 07. pii: 2026.06.03.729837. [Epub ahead of print]
    Copper transport to mitochondria by SLC25A3 contributes to skeletal myoblast differentiation and is required for survival of differentiated myotubes.
    Alexandra M Perez, Jason D Fivush, Bailey M Cordill, Nathan Ferguson, Yu Zhang, Allison T Mezzell, Ushodaya Mattam, Omar Chaudhry, Karleigh G Porter, Saanvi Maadaadi, Dina Secic, Megan Bischoff, Karthickeyan Chella Krishnan, Rhett Kovall, Tom Cunningham, Maria Czyzyk-Krzeska, Katherine E Vest.
      Differentiation of skeletal muscle is associated with increased mitochondrial biogenesis and reliance of oxidative phosphorylation (OXPHOS). The terminal enzyme complex in the electron transport chain, cytochrome c oxidase (COX), requires copper for its assembly and activity, and copper delivery to mitochondria is essential for OXPHOS. However, when mitochondrial copper becomes essential during skeletal myoblast differentiation is not known. Here, we show that genetic deficiency of the mitochondrial copper and phosphate carrier SLC25A3 induced prior to myoblast differentiation leads to the formation of smaller myotubes, but SLC25A3 deficiency induced in mature myotubes leads to cell death and detachment. Both phenotypes are recapitulated upon genetic knockdown of COX17, a critical assembly protein for both COX copper cofactors, or by chemical inhibition of COX. Importantly, myotube death caused by SLC25A3 deficiency is rescued by copper supplementation or expression of an SLC25A3 variant that transports copper but not phosphate. Taken together these data support a model wherein copper transport by SLC25A3 and copper delivery to COX is critical for survival in mature myotubes.
    DOI:  https://doi.org/10.64898/2026.06.03.729837
  2. bioRxiv. 2026 Jun 01. pii: 2026.05.28.728419. [Epub ahead of print]
    Structure determination and dual targeting of a plant TACO1 identifies its ancient role as an organelle translation regulator.
    Parth K Raval, Nuša Kos Thaler, Cristopher Mitchell, Maria Lozano-Quiles, Tommi Kajander, Daniel W Djamriani, Jens Reiners, Sander Hj Smits, Sarah J Butcher, Brendan J Battersby, Sven B Gould.
      Ribosome stalling caused by polyproline (PPs) motifs is common. Their translation is enhanced by accessory proteins such as YebC in bacteria, whose homolog, TRANSLATIONAL ACTIVATOR OF CYTOCHROME C OXIDASE 1 (TACO1), aids the translation of mitochondria-encoded proteins. The prevalence of PP motifs across plastid-encoded genes and their impact on the translation of photosynthesis-relevant proteins remains unexplored. Equally, a translation-enhancer of PP motifs equivalent to TACO1 for plastid ribosomes has not been reported. Here, we show that plastid genomes encode 24 proteins with a minimum of one PP motif on average, half of which are conserved in their cyanobacterial homologs, and that the vast majority of eukaryotes, including plants, encode a single TACO1 that we demonstrate to be dually targeted to mitochondria and plastids of Marchantia polymorpha . We resolved the MpTACO1 structure at 2.34 Å by X-ray crystallography and the flexibility by small-angle X-ray scattering. Through modelling, we demonstrate that MpTACO1 can fit into the peptidyl transfer centre of plant chlororibosomes in a similar manner as human TACO1 in the mitoribosome. The identification and structure determination of the first plastid-targeted YebC/TACO1 allows us to sketch a unified model for the function and evolution of this ancient family of ribosomal accessory proteins, underscoring their indispensable role in the translation of bioenergetic membrane proteins reaching back almost 4 billion years.
    Highlights: Dozens of GC-rich polyproline (PP) encoding regions are retained by AT-rich genomesPP motif conservation hints at regulatory mechanisms and required translation pausesChloroplast targeting of a (mitochondrial) translation enhancer of PP motifsMpTACO1 structure at 2.34 Å resolution demonstrates its high level of conservation.
    DOI:  https://doi.org/10.64898/2026.05.28.728419
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