{"id":322789,"date":"2026-02-06T03:56:09","date_gmt":"2026-02-06T03:56:09","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/322789\/"},"modified":"2026-02-06T03:56:09","modified_gmt":"2026-02-06T03:56:09","slug":"power-of-tiny-molecular-flycatcher-surprises-through-disorder","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/322789\/","title":{"rendered":"Power of Tiny Molecular ‘Flycatcher’ Surprises Through Disorder"},"content":{"rendered":"

\n\t\t\t\t\t\t\t\t\t\tBYLINE:<\/strong> Jenny Green\t\t\t\t\t\t\t\t\t\t<\/p>\n

Newswise \u2014 For decades, scientists assumed that order drives efficiency. Yet in the bustling machinery of mitochondria \u2014 the organelles that crank out adenosine triphosphate (ATP), the universal \u201cenergy currency\u201d of cells \u2014 one of the most enigmatic components is a protein that appears anything but orderly.<\/p>\n

ATP powers nearly every biological task, from muscle contraction to neural signaling, by breaking high-energy phosphate bonds and being continually recharged through metabolism. This life-sustaining energy cycle depends on highly coordinated flows of electrons within respiratory supercomplexes. And nestled within these mega-assemblies is\u00a0QCR6, a tiny ubiquitous protein found in bacteria, yeast and humans whose acidic, floppy tail has remained structurally unresolved for decades. Traditional experimental methods simply couldn\u2019t pin it down; it was too disordered, too mobile, too electrically charged to freeze into a single, clean conformation.<\/p>\n

Yet this very disorder, a new study shows, may be the secret to making life run efficiently.<\/p>\n

Abhishek Singharoy, associate professor in ASU\u2019s\u00a0School of Molecular Sciences<\/a>\u00a0and\u00a0associate faculty in the\u00a0Biodesign Center for Applied Structural Discovery<\/a>\u00a0is the\u00a0senior author\u00a0on the\u00a0Nature Communications study<\/a>\u00a0published today.<\/p>\n

\u201cThe biological significance of protein supercomplexes has remained contentious, particularly how they tune the shuttling of charge-carrier redox proteins\u00a0along with<\/a>\u00a0cell membranes during biological energy conversion,\u201d Singharoy said.<\/p>\n

Supercomplexes \u2014 large assemblies of multiple protein complexes \u2014 were once primarily associated with photosynthesis, but are now known to appear across biology. Respiratory chains in bacteria, yeast, plants and humans all build these molecular megastructures. And intriguingly, their individual enzymes work\u00a0just as well\u00a0outside of these assemblies as within them.<\/p>\n

So why form a supercomplex at all?<\/p>\n

The answer, it turns out, doesn\u2019t lie in enzymatic reaction speed. Instead, it lies in something more fundamental:\u00a0how quickly substrates can find their way to the proteins that process them.<\/p>\n

As Jon Nguyen, a former graduate student in the Singharoy lab and now a postdoctoral research associate at Michigan State University\u2019s Plant Research Laboratory, and a shared first author of the study, explained,\u00a0\u201cFor decades, a highly disordered protein, QCR6, in mitochondrial supercomplexes was thought to enhance electron transfer and ATP production. However, experimental methods have, to this day, been unable to resolve the structure of QCR6 because of its acidic and flexible region.<\/p>\n

\u201cNow, using computational methods informed by experimental data, we present a model. Our simulations reveal that this highly disordered protein actually lowers the energy barrier for the diffusion of electron carriers during electron transfer, thereby increasing overall energy-conversion efficiency.\u201d<\/p>\n

In discussing the main image of this story above, Chun Kit Chan, postdoctoral research associate and shared first author of this study said, \u201cEfficient metabolism is key to an organism\u2019s survival. In this study, we revealed that QCR6 (the red, shining tube in the above image), a tiny, acidic domain of a yeast respiratory complex, can leverage its intrinsic disorder to hover (highlighted by the white wireframe in the above image) over respiratory protein condensates and cooperate with the surrounding acidic membrane environment to provide a folding-unfolding-based, guided diffusion to electron-shuttling enzymes (the colorful, small proteins in the above image), speeding up intra-protein electron transfers \u2014 and thus metabolism-linked ATP production \u2014 by up to 30%.<\/p>\n

\u201cHomologs of QCR6 are also present in the human respiratory system, leading us to wonder if the seemingly chaotic dynamics from the protein’s disorder might actually be the means to prompt our survival fitness.\u201d<\/p>\n

But this new work pushes the idea even further.<\/p>\n

The team combined\u00a0multi-resolution computational methods,\u00a0entropy-maximizing molecular dynamics,\u00a0Brownian diffusion simulations and\u00a0cryo-EM data\u00a0to build the first proposed structural ensemble for QCR6\u2019s elusive tail. What emerged was startling.<\/p>\n

Rather than being a passive, floppy ornament, the disordered acidic region behaves like a\u00a0molecular flycatcher.<\/a><\/p>\n

The simulations revealed that QCR6\u2019s acidic, flexible region forms a shifting corona around the respiratory supercomplex. Positively charged electron carriers, like cytochrome\u00a0c, are electrostatically attracted to this zone. The mobile tail\u00a0reaches, hooks and shepherds the electron carriers\u00a0toward the reaction centers. This reduces the energy barrier for carriers to arrive at the correct location \u2014 making electron transfer\u00a0faster and more reliable.<\/p>\n

In other words, QCR6 doesn\u2019t improve the chemistry of electron transfer; it improves the\u00a0recognition problem \u2014 getting the reactants to the right place at the right time.<\/p>\n

This is a fundamentally different mode of efficiency \u2014 not catalytic, but\u00a0logistical.<\/p>\n

Across simulations and experimental constraints, the team found that the presence of QCR6\u2019s disordered hook can accelerate substrate delivery and boost metabolism-linked ATP production by\u00a0up to 30%. Intriguingly, this increase matches unexplained experimental observations reported years earlier but never mechanistically resolved.<\/p>\n

Working with collaborator\u00a0and School of Molecular Sciences Professor\u00a0Kevin Redding<\/a>, the team also mapped how QCR6-like proteins vary across evolution. Primitive organisms such as heliobacteria lack these highly acidic, mobile hooks. Instead, their cytochrome electron carriers are literally\u00a0tethered\u00a0to the membrane \u2014 like balloons tied to a string \u2014 to ensure they don\u2019t drift away.<\/p>\n

“The heliobacterial cytochrome c is linked directly to a membrane lipid, with a ‘leash’ between that attachment site and the cytochrome domain,\u201d Redding explained. \u201cUnlike mitochondria, these bacteria don’t have an outer membrane to keep everything inside; they link it physically, so the cytochrome cannot wander off.<\/p>\n

\u201cWhen we compared these leashes between species, we saw poor conservation of the exact sequence \u2014 what is maintained is the\u00a0length\u00a0of the leash and its\u00a0composition, which is dominated by amino acids that confer flexibility. So, like QCR6, a flexible polypeptide chain is used to keep the cytochrome near its partners to facilitate rapid electron transfer, just in a different way that matches the needs of these cells better.”<\/p>\n

This evolutionary comparison reinforces the central claim: The QCR6 region is not accidental disorder but\u00a0functional disorder \u2014 an elegant evolutionary innovation for optimizing electron-transfer traffic.<\/p>\n

From cryo-EM haze to high-resolution insight<\/p>\n

Because QCR6\u2019s tail refuses to sit still, cryo-EM has long captured it only as a blurry smear. The team\u2019s strategy flipped the traditional workflow: Instead of fitting experimental haze into a structure, they generated a high-resolution structural ensemble computationally and then \u201cblurred\u201d it to see if it reproduced the cryo-EM noise signature.<\/p>\n

It did.<\/p>\n

That convergence offered the first plausible structural interpretation of QCR6 \u2014 a model consistent with both its disorder and the known electrostatic environment of the respiratory supercomplex.<\/p>\n

This work required enormous computational power, drawing on\u00a0DoD supercomputers, DOE\u2019s\u00a0Summit\u00a0and\u00a0Frontier, and years of simulation time. It also relied on key collaborations \u2014 cryo-EM expertise from\u00a0Eugenia\u00a0Mileykovskaya\u00a0and\u00a0Matthew Baker (UT Health, Houston, Texas), evolutionary analysis with\u00a0Redding, and the efforts of first authors\u00a0Chun Kit Chan\u00a0and\u00a0Jonathan Nguyen.<\/p>\n

The central idea emerging from this work is striking: A protein can gain functional power precisely by not having a fixed structure.<\/strong><\/p>\n

QCR6\u2019s mobility, electrostatics and ability to fold and unfold near the membrane create a guided-diffusion mechanism that brings order to electron-transfer chaos. And the consequences ripple upward: from molecular recognition to reaction efficiency to overall cellular fitness. Indeed, the team\u2019s models predict \u2014 and experiments confirm \u2014 that cells can grow\u00a030% faster\u00a0when this mechanism is active.<\/p>\n

The discovery reframes how we think about disorder in biology. Sometimes, chaos is not a flaw.
Sometimes, it is a design principle.<\/p>\n","protected":false},"excerpt":{"rendered":"BYLINE: Jenny Green Newswise \u2014 For decades, scientists assumed that order drives efficiency. Yet in the bustling machinery…\n","protected":false},"author":2,"featured_media":322790,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[77],"tags":[7260,155614,7580,18,7520,155613,19,17,3618,941,155612,133],"class_list":["post-322789","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-all-journal-news","tag-arizona-state-university-asu","tag-cell-biology","tag-eire","tag-energy","tag-evolution-and-darwin","tag-ie","tag-ireland","tag-nature","tag-newswise","tag-proteinmitochondia","tag-science"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/116021676132520569","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/322789","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=322789"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/322789\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/322790"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=322789"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=322789"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=322789"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}