How Cryo-Em Advances Structural Biology

SCIENTISTS DECODE KEY MOTIONS BEHIND BRAIN'S TRANSPORT Cells depend on motor proteins like dynein to shuttle materials along microscopic highways, and dysfunction in these proteins can lead to serious neurological disorders. New research captured real-time, high-resolution “movies” of dynein being activated by its partner protein, Lis1, illuminating the step-by-step process. Scientists observed 16 distinct 3D shapes in the dynein-Lis1 interaction, revealing new insights into how Lis1 unlocks and powers up dynein. These findings could help design targeted treatments for diseases like lissencephaly by restoring proper dynein activity. Key Facts: 1. Dynein Activation: Lis1 initiates dynein’s activity by binding to its motor and stalk, transitioning it from an inactive “Phi” state to an active “Chi” state. 2. New Imaging Breakthrough: Time-resolved cryo-electron microscopy captured dynein’s activation in unprecedented detail, revealing 16 structural stages. 2. Clinical Implication: Understanding these molecular steps could inform therapeutic strategies for neurodevelopmental disorders linked to dynein or Lis1 dysfunction. Source: https://lnkd.in/gCKS7qYJ

A study in Cell reports the first high-resolution structures of measles virus polymerase complex (the molecular “machine” that builds viruses) alone and with inhibitors. The researchers used these structures to show that one of the inhibitors also works against Nipah virus! First, some context on measles: The measles virus is a negative-sense RNA virus from the Paramyxoviridae family. Its genome cannot be "read" by ribosomes directly; it must first be converted into positive-sense RNA, which is then used as a template to build proteins. When measles enters a host cell, it releases its RNA genome. But because this genome can't be read by the host cell's ribosomes, the virus ALSO brings in its own polymerase complex—made of the large (L) protein and a phosphoprotein (P). Together, L- and P act as an RNA-dependent RNA polymerase, transcribing the viral genome into mRNA so that the host’s ribosomes can begin making viral proteins. There are no FDA-approved therapies to treat measles, but researchers have been searching for molecules that could shut down this L-P polymerase. ERDRP-0519 has emerged as one of the most promising. In animal studies, it protected monkeys from otherwise lethal doses of measles virus. It works as a non-nucleoside inhibitor, meaning it doesn’t mimic a normal RNA base—instead, it binds somewhere else on the polymerase and interferes with its function indirectly. Despite past success in preclinical studies, no one had yet figured out how, exactly, these drugs work; where they bind, how they shut down the polymerase, etc. For this paper, theresearchers used cryo-EM to figure that out! They solved the structure of the L-P polymerase complex in isolation, and also together with these inhibitors. They found that the ERDRP-0519 molecule binds to a pocket near a conserved loop in the L protein known as the GDN loop (it is named this because it is made from glycine-aspartate-asparagine.) This loop helps position magnesium ions needed for RNA synthesis. But when the inhibitor molecule binds, it pushes the GDN loop into an “out” conformation that prevents the protein from coordinating with the magnesium ions. And without magnesium, the polymerase can’t catalyze RNA synthesis; it becomes inactive. In biochemistry textbooks, this is called ALLOSTERIC INHIBITION, because the drug binds away from the active site, even though its effects are still fatal to the enzyme. The most exciting part of this paper, though, is what came next: the team realized that a similar binding pocket exists in the polymerase of another virus: Nipah. The Nipah virus is also a member of the Paramyxoviridae family, but it’s far more lethal, with fatality rates of up to 70%. Using structural alignment and biochemical assays, the authors showed that ERDRP-0519 binds to the Nipah polymerase with even higher affinity than it does to measles, and at the same GDN loop position. Thanks for reading! Link: https://lnkd.in/eqBnNbDH

Unveiling the Molecular Architecture of Light Chain Amyloids in Heart Failure: A Stepping Stone for New Therapies 𝘛𝘩𝘪𝘴 𝘴𝘵𝘶𝘥𝘺 𝘥𝘦𝘭𝘷𝘦𝘴 𝘪𝘯𝘵𝘰 𝘵𝘩𝘦 𝘴𝘵𝘳𝘶𝘤𝘵𝘶𝘳𝘢𝘭 𝘶𝘯𝘥𝘦𝘳𝘱𝘪𝘯𝘯𝘪𝘯𝘨𝘴 𝘰𝘧 𝘢 𝘥𝘦𝘣𝘪𝘭𝘪𝘵𝘢𝘵𝘪𝘯𝘨 𝘩𝘦𝘢𝘳𝘵 𝘤𝘰𝘯𝘥𝘪𝘵𝘪𝘰𝘯, 𝘢𝘮𝘺𝘭𝘰𝘪𝘥𝘰𝘴𝘪𝘴 𝘭𝘪𝘨𝘩𝘵 𝘤𝘩𝘢𝘪𝘯 (𝘈𝘓) 𝘢𝘮𝘺𝘭𝘰𝘪𝘥𝘰𝘴𝘪𝘴. 𝘛𝘩𝘦 𝘤𝘰𝘯𝘥𝘪𝘵𝘪𝘰𝘯 𝘢𝘳𝘪𝘴𝘦𝘴 𝘸𝘩𝘦𝘯 𝘢𝘣𝘯𝘰𝘳𝘮𝘢𝘭 𝘱𝘳𝘰𝘵𝘦𝘪𝘯 𝘧𝘳𝘢𝘨𝘮𝘦𝘯𝘵𝘴, 𝘬𝘯𝘰𝘸𝘯 𝘢𝘴 𝘭𝘪𝘨𝘩𝘵 𝘤𝘩𝘢𝘪𝘯 𝘱𝘳𝘰𝘵𝘦𝘪𝘯𝘴, 𝘤𝘭𝘶𝘮𝘱 𝘵𝘰𝘨𝘦𝘵𝘩𝘦𝘳 𝘢𝘯𝘥 𝘪𝘯𝘧𝘪𝘭𝘵𝘳𝘢𝘵𝘦 𝘵𝘩𝘦 𝘩𝘦𝘢𝘳𝘵, 𝘥𝘪𝘴𝘳𝘶𝘱𝘵𝘪𝘯𝘨 𝘪𝘵𝘴 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯. 𝘛𝘩𝘦 𝘴𝘦𝘷𝘦𝘳𝘪𝘵𝘺 𝘰𝘧 𝘩𝘦𝘢𝘳𝘵 𝘪𝘯𝘷𝘰𝘭𝘷𝘦𝘮𝘦𝘯𝘵 𝘴𝘪𝘨𝘯𝘪𝘧𝘪𝘤𝘢𝘯𝘵𝘭𝘺 𝘪𝘮𝘱𝘢𝘤𝘵𝘴 𝘱𝘢𝘵𝘪𝘦𝘯𝘵 𝘱𝘳𝘰𝘨𝘯𝘰𝘴𝘪𝘴. 𝗗𝗲𝗰𝗶𝗽𝗵𝗲𝗿𝗶𝗻𝗴 𝘁𝗵𝗲 𝗣𝗿𝗼𝘁𝗲𝗶𝗻 𝗔𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲 𝘄𝗶𝘁𝗵 𝗛𝗶𝗴𝗵-𝗥𝗲𝘀𝗼𝗹𝘂𝘁𝗶𝗼𝗻 𝗜𝗺𝗮𝗴𝗶𝗻𝗴 Researchers employed a powerful imaging technique, cryo-electron microscopy (cryo-EM), to examine these protein clumps, or amyloids, extracted from the heart tissue of an AL amyloidosis patient experiencing severe heart failure. This cutting-edge technique provided a detailed, three-dimensional picture of the amyloid structure at an impressive resolution of 4.0 angstroms (Å), where one angstrom is a ten-billionth of a meter. 𝗕𝘂𝗶𝗹𝗱𝗶𝗻𝗴 𝘁𝗵𝗲 𝗕𝗹𝗼𝗰𝗸 𝗠𝗼𝗱𝗲𝗹: 𝗜𝗱𝗲𝗻𝘁𝗶𝗳𝘆𝗶𝗻𝗴 𝘁𝗵𝗲 𝗖𝘂𝗹𝗽𝗿𝗶𝘁 𝗣𝗿𝗼𝘁𝗲𝗶𝗻𝘀 Based on the cryo-EM data, the researchers constructed a molecular model of the amyloid fibrils. These fibrils were found to be thread-like structures, each consisting of a single strand (protofilament) with a characteristic cross-β architecture—a common arrangement in amyloid proteins—and a repeating pattern every 4.9 Å. Notably, two distinct stretches of amino acids, totaling 77 residues, from the variable region (Vl) of the light chain protein were identified as the building blocks of these fibrils. 𝗕𝗲𝘆𝗼𝗻𝗱 𝗦𝗲𝗾𝘂𝗲𝗻𝗰𝗲 𝗩𝗮𝗿𝗶𝗮𝗯𝗶𝗹𝗶𝘁𝘆: 𝗨𝗻𝘃𝗲𝗶𝗹𝗶𝗻𝗴 𝗖𝗼𝗺𝗺𝗼𝗻 𝗧𝗵𝗿𝗲𝗮𝗱𝘀 The Vl region exhibits a high degree of variability in its amino acid sequence across different patients. However, the researchers discovered that specific residues within this region, crucial for stabilizing the core of the amyloid fibril, were remarkably conserved across various cardiotoxic (heart-damaging) Vl sequences. This finding suggests the presence of structural motifs, or patterns, that might be common to light chain proteins prone to misfolding and aggregation in AL amyloidosis. 📖 Article https://lnkd.in/eVNkzghv 🕊 CC 4.0 https://lnkd.in/etXvAShM 📷 EM Map https://lnkd.in/eaY28bGG 🏛 EMDB https://lnkd.in/ePU9n4kv Swuec P, Lavatelli F, Tasaki M, Paissoni C, Rognoni P, Maritan M, Brambilla F, Milani P, Mauri P, Camilloni C, Palladini G, Merlini G, Ricagno S, Bolognesi M. Nat Commun (2019) #team4disease #merize #research #structuralbiology