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M153R mutation in a pH-sensitive green fluorescent protein stabilizes its fusion proteins.

ABSTRACT: BACKGROUND: Green fluorescent protein (GFP) and its fusion proteins have been used extensively to monitor and analyze a wide range of biological processes. However, proteolytic cleavage often removes GFP from its fusion proteins, not only causing a poor signal-to-noise ratio of the fluorescent images but also leading to wrong interpretations. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report that the M153R mutation in a ratiometric pH-sensitive GFP, pHluorin, significantly stabilizes its fusion products while the mutant protein still retaining a marked pH dependence of 410/470 nm excitation ratio of fluorescence intensity. The M153R mutation increases the brightness in vivo but does not affect the 410/470-nm excitation ratios at various pH values. CONCLUSIONS/SIGNIFICANCE: Since the pHluorin(M153R) probe can be directly fused to the target proteins, we suggest that it will be a potentially powerful tool for the measurement of local pH in living cells as well as for the analysis of subcellular localization of target proteins.

SUBMITTER: Morimoto YV

PROVIDER: S-EPMC3086926 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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M153R mutation in a pH-sensitive green fluorescent protein stabilizes its fusion proteins.

Morimoto Yusuke V YV Kojima Seiji S Namba Keiichi K Minamino Tohru T

PloS one 20110503 5

<h4>Background</h4>Green fluorescent protein (GFP) and its fusion proteins have been used extensively to monitor and analyze a wide range of biological processes. However, proteolytic cleavage often removes GFP from its fusion proteins, not only causing a poor signal-to-noise ratio of the fluorescent images but also leading to wrong interpretations.<h4>Methodology/principal findings</h4>Here, we report that the M153R mutation in a ratiometric pH-sensitive GFP, pHluorin, significantly stabilizes ...[more]

PMID: 21559297

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Project description:Chemically synthesized near-infrared aza-BODIPY dyes displayed off-on fluorescence at acidic pH (pKa = 6.2-6.6) through the suppression of the photoinduced electron transfer and/or internal charge transfer process. The apparent pKas of the dyes were shifted well above physiological pH in a hydrophobic microenvironment, which led to "turned-on" fluorescence in micelles and liposomes at neutral and basic pH. Bovine serum albumin also activated the fluorescence, though to a much lesser extent. When these small molecular dyes entered cells, instead of being fluorescent only in acidic organelles, the whole cytoplasm exhibited fluorescence, with a signal/background ratio as high as ?10 in no-wash live-cell imaging. The dye 1-labeled cells remained highly fluorescent even after 3 days. Moreover, slight variations of the dye structure resulted in significantly different intracellular fluorescence behaviors, possibly because of their different cellular uptake and intracellular activation capabilities. After the separation of cellular components, the fraction of plasma membrane and endoplasmic reticulum showed the highest fluorescence, further confirming the fluorescence activation by membrane structures. The fluorescence intensity of these dyes at different intracellular pHs (6.80 and 8.00) did not differ significantly, indicating that intracellular pH did not play a critical role. Altogether, we showed here for the first time that the fluorescence of pH-sensitive aza-BODIPY dyes was switched intracellularly not by acidic pH, but by intracellular membranes (and proteins as well). The excellent membrane permeability, ultrahigh fluorescence contrast ratio, persistent fluorescent signal, and minimal biological interference of dye 1 make it an ideal choice for live-cell imaging and in vivo cell tracking. These findings also imply that the intracellular fluorescence properties of pH-sensitive dyes should be carefully examined before they are used as pH indicators.

Dataset Information

M153R mutation in a pH-sensitive green fluorescent protein stabilizes its fusion proteins.

Publications

M153R mutation in a pH-sensitive green fluorescent protein stabilizes its fusion proteins.

Similar Datasets

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