{"id":495359,"date":"2026-06-12T03:23:08","date_gmt":"2026-06-12T03:23:08","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/495359\/"},"modified":"2026-06-12T03:23:08","modified_gmt":"2026-06-12T03:23:08","slug":"laser-driven-phase-contrast-enhances-cryo-em-resolution-of-small-proteins","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/495359\/","title":{"rendered":"Laser\u2011Driven Phase Contrast Enhances Cryo\u2011EM Resolution of Small Proteins"},"content":{"rendered":"

\"Proteins\"<\/a>Credit: Christoph Burgstedt\/Science Photo Library\/Getty Images<\/p>\n

You know when you are at the eye doctor getting an updated prescription, and suddenly the world snaps into sharper focus? Physicists at the University of California (UC), Berkeley, have now done something similar for electron microscopy. By introducing phase contrast into a cryo\u2011electron microscope, they have delivered dramatically sharper images of some of biology\u2019s smallest and most elusive proteins.<\/p>\n

The advance comes from a new laser phase plate (LPP), described in the paper \u201cLaser phase plate improves structure determination of small proteins by cryo\u2011EM,<\/a>\u201d which was published recently in Science. Led by physicist Holger Mueller, PhD, of UC Berkeley and Lawrence Berkeley National Laboratory, the team demonstrated that a laser\u2011driven phase plate can overcome one of cryo\u2011EM\u2019s most persistent limitations: poor contrast for small proteins.<\/p>\n

\"\"Cryo-EM images of two proteins, apoferritin and hemoglobin, taken without and with a laser phase plate. The images are analyzed in a computer to produce detailed 3D structures of the proteins. [Holger M\u00fcller, Jessie Zhang\/UC Berkeley]Cryo\u2011EM has transformed structural biology over the past decade, earning a Nobel Prize in 2017 for enabling high\u2011resolution structures without crystallization. But despite its impact, the technique still struggles with proteins below ~70 kilodaltons\u2014a size range that includes about 90% of the human proteome. \u201cBecause of signal-to-noise limitations, the majority of human and animal proteins are too small to be analyzed by these methods [cryo-EM and cryoelectron tomography]. The increase in signal-to-noise ratio provided by this laser phase plate is expected to overcome these important limitations.\u201d<\/p>\n

The new LPP begins to address that problem. The LPP uses an intense, continuous\u2011wave laser to shift the phase of the electron beam itself. This produces true phase contrast without dimming or destabilizing the beam. Mueller described the laser focus as \u201c75 kilowatts focused to a few microns\u2026 That\u2019s more powerful than what you use for welding. It has more power than a military laser. It builds up the brightest continuous laser focus ever.\u201d<\/p>\n

Installed in a custom Thermo Fisher Titan Krios, the LPP immediately improved the clarity and resolvability of small proteins, including hemoglobin, which sits at the lower limit of what today\u2019s cryo\u2011EM instruments can handle. As the authors wrote in the abstract: \u201cHere, we show that the laser phase plate (LPP)\u2026 enhances the resolution in single-particle reconstruction of small proteins by improving specimen-motion correction, recovery of information from the early frames, as well as particle visualization, 3D classification, and alignment.\u201d<\/p>\n

\"phaseA laser (purple) is powerfully amplified by highly polished mirrors and focused on the electron beam (blue) to shift its phase and increase the cryo-EM microscope\u2019s contrast, allowing biologists to image smaller proteins and the crowded structures inside cells. [Sayo Studio]These improvements were achieved using standard defocus ranges and reconstruction workflows. \u201cFor the most challenging cases\u2014small particles, bad specimens\u2014the laser produces a very considerable advantage,\u201d Mueller said.<\/p>\n

\u00a0<\/p>\n

The impact extends beyond single\u2011particle analysis. Cryo\u2011electron tomography (cryo\u2011ET), which assembles multiple angular views of a molecule or protein into a three-dimensional image, stands to benefit even more. \u201cWith cryo-ET, we\u2019re looking at small, very complicated cellular material that\u2019s incredibly crowded inside the cell,\u201d said Bridget Carragher, PhD, founding technical director of imaging at Biohub. \u201cIt\u2019s like a forest of trees, and you\u2019re trying to find one leaf on one tree in there. Cryo-ET needs a dramatic step forward in contrast, so we can start to see what\u2019s going on inside the cell. That\u2019s what the laser phase plate promises to give us.\u201d<\/p>\n

Biohub is developing a dual\u2011laser version of the system, designed to reduce component wear and minimize aberrations. Meanwhile, Mueller\u2019s team is pushing toward imaging proteins as small as 17 kilodaltons, a threshold that would open access to vast regions of the human proteome previously invisible to cryo\u2011EM.<\/p>\n

\u201cThis technology is a step function change for biology,\u201d said Stephani Otte, PhD, Biohub\u2019s vice president of imaging science. \u201cWhat was once invisible will become visible\u2014and that changes everything about how we understand disease.\u201d<\/p>\n

\u201cThe bottom line is, if you have a large protein and a really good sample\u2014a fresh one or one frozen without bubbles, for example\u2014you may not need the phase plate to get a single, high-quality image. But for a small protein and a bad sample, laser-on is best,\u201d Mueller said. \u201cThis could fill an enormous gap in our knowledge of protein structures that can\u2019t be crystallized or are too small for today\u2019s cryo-EM. And it will be revolutionary for cryo-ET.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Credit: Christoph Burgstedt\/Science Photo Library\/Getty Images You know when you are at the eye doctor getting an updated…\n","protected":false},"author":2,"featured_media":495360,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[2877,61,60,43,82],"class_list":["post-495359","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-drug-discovery","tag-ie","tag-ireland","tag-news","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/495359","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=495359"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/495359\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/495360"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=495359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=495359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=495359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}