By Irene Hsiao
Lysosomes are spherical, enzyme-containing vesicles that break down waste within most animal cells. When an enzyme within the lysosome fails to function, the resulting accumulation of waste causes disease. About 70 such diseases have been identified. In a paper published in eLife 25 July 2017, Kasturi Chakraborty, KaHo Leung, and Yamuna Krishnan used Clensor, a DNA nanodevice, to measure chloride levels in the lysosomes of living C. elegans, as well as cultured mice and human cells, showing that diseased lysosomes exhibit reduced levels of chloride. The authors described a fundamental new role for chloride in biology. Chloride has always been considered a passive ion that functioned only to balance ionic changes due to cation fluxes. This work shows that high chloride was essential for the catalytic activity of enzymes resident in the lysosome, whose activity crucial for normal function of the lysosome.