MIT researchers are shedding light on how proteins are strategically crafted right where they're needed in our cells, a process that poses implications for understanding disease and cell functions. Led by biology professor Jonathan Weissman and postdoc Jingchuan Luo, they’ve unmasked how localized translation functions at mitochondria, with their findings recently laid out in MIT News. Their work revolves around a novel tool, LOCL-TL, that deciphers the creation of proteins adjacent to mitochondria, our cellular powerhouses.
Originating as independent bacteria, mitochondria evolved to become integral parts of our cells, including incorporating most of their genetic material into our own DNA; this necessitates a coordination between the proteins produced by their own tiny genomes and those encoded within the nucleus of cells, proteins made on-site at these organelles may help streamline this intricate orchestration and Weissman's team is probing this process with considerable depth. "Being able to see what section of the protein is locally translated helps us understand more about how localized translation is regulated, which can then allow us to understand its dysregulation in disease and to control localized translation in future studies," Luo said, detailing the granularity this innovative tool provides in an interview obtained by MIT News.
The LOCL-TL methodology developed by Luo and Weissman circumvents traditional challenges by utilizing blue light instead of biotin, a compound necessary for normal mitochondria function and therefore cannot be depleted during experiments. Hence, their technique involves the use of LOV-BirA, a tagging mechanism anchored to the mitochondrial membrane that starts tagging ribosomes—molecular complexes that synthesize proteins—when exposed to blue light, allowing precise capture of these protein-synthesizing ribosomes at the mitochondria.
Crucial insights have emerged from this research, revealing that approximately 20 percent of the proteins required by mitochondria are actually translated right on their surface, this direct synthesis includes two classes of proteins: ancestral ones from their bacterial origins and newer, shorter proteins that utilize a different mechanism for localized translation. For the longer, bacterial-origin proteins, they discovered those missing a regulatory sequence are transported to mitochondria mid-production, whereas shorter ones have their transport guided by RNA sequences, with protein AKAP1 playing a pivotal role in this process - as presented in the MIT News article.
Looking ahead, Weissman and Luo intend to delve deeper into the broader implications of their discoveries, including how localized translation could influence mitochondrial dysfunction in diseases. Weissman asserts in MIT News, "This approach should be broadly applicable to different cellular structures and cell types, providing many opportunities to understand how localized translation contributes to biological processes." This emphasis on the potential applications of their work highlights a developing frontier in the study of cellular biology, particularly in relation to neurodegeneration, cardiovascular diseases, and cancers.
