| Comments |
P.1146 left column: "Effects of membrane protein expression and lipid biosynthesis mutations on the mobility of BODIPY FL-C12: To further explore the factors controlling the mobility of BODIPY FL-C12, [investigators] measured its diffusion coefficient in cells with different membrane protein and lipid compositions (summarized in Table 1). To perturb membrane protein composition, [they] used a mutant lacking the entire twin-arginine translocation (tat) operon (Wexler et al., 2000), with and without a pBad plasmid overexpressing tatABC (Bolhuis et al., 2001). After arabinose induction, the TatABC proteins pack the membrane (Bolhuis et al., 2001). However, neither condition measurably perturbed the BODIPY FL-C12 diffusion coefficient (Table 1). [They] then also tried a series of mutants with deletions of genes coding for lipid biosynthesis enzymes (Dowhan, 1997): cardiolipin synthetase (cls) pssA (required for phosphatidylserine synthesis) pgsA (phosphatidylglycerophosphate synthetase) and phosphatidylserine decarboxylase (psd). Some of these mutants showed significant alteration of the BODIPY FL-C12 diffusion coefficient, by a factor of up to ∼ 2 in either direction (Table 1)." P.1147 left column 2nd paragraph: "[Investigators] measured helix1021-GFP diffusion in the set of lipid biosynthesis mutants also used to measure effects of membrane lipid composition on BODIPY FL-C12 diffusion (Table 1). Effects on helix1021-GFP diffusion were generally much smaller than with BODIPY FL-C12 diffusion, and there was no obvious correlation between the effects on helix1021-GFP and BODIPY FL-C12 diffusion (Table 1). For example, the BODIPY FL-C12 diffusion coefficient was respectively increased and decreased by a factor of about 2 in the ΔpssA and ΔlppΔpgsA mutants, with no significant effects on helix1021-GFP diffusion (paired t-test, P = 0.129, n = 10 (Table 1)." BODIPY FL-C12 is a green fluorescent fatty acid derivative. Helix1021-GFP
is a model membrane protein |