Original dataset and processing code supporting the preprint (scientific publication) "mScarlet fluorescence lifetime reports lysosomal pH quantitatively." Publication Abstract: The lysosome maintains a highly acidic pH, which is critical for successful lysosomal catabolism. Lysosomal pH (pHlys) is difficult to measure because of the simultaneous need for a sensor with large dynamic range, genetic targetability, low pKa, and a quantitative readout. Here, we demonstrate that the fluorescence lifetime of the mScarlet-LAMP1 fusion protein quantitatively reports lysosomal pH, exhibiting a large dynamic range and a pKa well-tuned for the lysosome. Because fluorescence lifetime is an intrinsic property, pH measurements can be achieved in a single fluorescence channel. mScarlet-LAMP1 lifetime allows for individual lysosome-resolved recordings, a critical advance in describing and understanding pHlys heterogeneity. Using this biosensor, we quantify heterogeneity of pHlys in cultured cells at rest and over time during drug treatment. We anticipate that mScarlet-LAMP1 will enable new insights into the diversity of lysosomal physiology and ionic milieu.

Original dataset and processing code supporting the preprint (scientific publication) "mScarlet fluorescence lifetime reports lysosomal pH quantitatively." Publication Abstract: The lysosome maintains a highly acidic pH, which is critical for successful lysosomal catabolism. Lysosomal pH (pHlys) is difficult to measure because of the simultaneous need for a sensor with large dynamic range, genetic targetability, low pKa, and a quantitative readout. Here, we demonstrate that the fluorescence lifetime of the mScarlet-LAMP1 fusion protein quantitatively reports lysosomal pH, exhibiting a large dynamic range and a pKa well-tuned for the lysosome. Because fluorescence lifetime is an intrinsic property, pH measurements can be achieved in a single fluorescence channel. mScarlet-LAMP1 lifetime allows for individual lysosome-resolved recordings, a critical advance in describing and understanding pHlys heterogeneity. Using this biosensor, we quantify heterogeneity of pHlys in cultured cells at rest and over time during drug treatment. We anticipate that mScarlet-LAMP1 will enable new insights into the diversity of lysosomal physiology and ionic milieu.