Ated (never modified) a-tubulin. B) COS7 and PtK2 cells expressing the acetytransferase mCit-MEC-17 (green) were double stained with monoclonal 6-11B-1 (red) and total tubulin (magenta) get BIBS39 antibodies (left panels) or with polyclonal anti-acetyl-K40 (red) and total tubulin (magenta) antibodies (right panels). Both antibodies recognize the Tubastatin-A highly acetylated microtubules induced by expression of mCit-MEC-17. Scale bars, 20 mm. (TIF) Figure S5 The 6-11B-1 epitope is sensitive to the level of expression of the a-tubulin K40 deacetylases HDAC6 andSIRT2. COS7 cells transfected with A) mCit-HDAC6 or B) mCitSIRT2 were fixed and stained with monoclonal 6-11B-1 (red) and total tubulin (magenta) antibodies. Scale bars, 20 mm. Transfected cells are indicated by a yellow dotted outline. Previous work showed that expression of HDAC6 or SIRT2 in mammalian cells resulted in a complete loss of 6-11B-1 staining [1?], suggesting that the 6-11B-1 antibody does not recognize deacetylated atubulin. In contrast, we show in Figure 4 that moderate expression of HDAC6 or SIRT2 results in deacetylated microtubules that can still be recognized by the 6-11B-1 antibody. To explain the difference between our results and the previous work, we looked at 6-11B-1 and anti-acetyl-K40 labeling at different levels of deacetylase expression. Figure 5 shows cells expressing moderate levels of HDAC6 and SIRT2 expression (based on fluorescence intensity) whereas this figure shows cells expressing high levels of HDAC6 and SIRT2. In agreement with previous work [1?], this figure shows that 6-11B-1 antigenicity is lost in cells expressing high levels of HDAC6 or SIRT2 enzymes. 24272870 The fact that the polyclonal anti-acetyl-K40 antibody does not recognize any microtubules even in cells expressing moderate levels of HDAC6 or SIRT2 enzymes (Figures 5B), indicates that expression of these deacetylase enzymes results in microtubules that are fully nonacetylated (deacetylated and unacetylated). The fact that 6-11B-1 stains microtubules in cells expressing moderate levels of HDAC6 or SIRT2 (Figure 5A) but not high levels of the enzymes (Figure S5) indicates that a-tubulin subunits undergo a structural conversion from the deacetylated (recognized by 6-11B-1) to non-acetylated (not recognized by 6-11B-1) state. Whether this conversion is due to increased levels or time of deacetylase expression is presently unclear. 1. North BJ, Marshall BL, Borra MT, Denu JM, Verdin E (2003) The human Sir2 ortholog, SIRT2, is an NAD(+)-dependent tubulin deacetylase. Mol Cell 11: 437-444. 2. Matsuyama A, Shimazu T, Sumida Y, Saito A, Yoshimatsu Y, et al. (2002) In vivo destabilization of dynamic microtubules by HDAC6-mediated deacetylation. EMBO J 21: 6820?831. 3. Zhang Y, Li N, Caron C, Matthias G, Hess D, et al. (2003) HDAC-6 interacts with and deacetylates tubulin and microtubules in vivo. EMBO J 22: 1168?179. (TIF)Figure S6 HDAC6 or SIRT2 binding does not create an epitope for the 6-11B-1 antibody in PtK2 cells. PtK2 cells expressing the deacetylases mCit-HDAC6 or mCit-SIRT2 (green) were fixed and double stained using monoclonal 6-11B-1 antiacetylated tubulin (red) and total tubulin (magenta) antibodies. Transfected cells are indicated by the yellow dotted outline. Scale bars, 20 mm. (TIF)Author ContributionsConceived and designed the experiments: VS JFH GS KJV. Performed the experiments: VS JFH. Analyzed the data: VS JFH GS KJV. Contributed reagents/materials/analysis tools: VS JFH GS KJV. Wrote the paper: VS J.Ated (never modified) a-tubulin. B) COS7 and PtK2 cells expressing the acetytransferase mCit-MEC-17 (green) were double stained with monoclonal 6-11B-1 (red) and total tubulin (magenta) antibodies (left panels) or with polyclonal anti-acetyl-K40 (red) and total tubulin (magenta) antibodies (right panels). Both antibodies recognize the highly acetylated microtubules induced by expression of mCit-MEC-17. Scale bars, 20 mm. (TIF) Figure S5 The 6-11B-1 epitope is sensitive to the level of expression of the a-tubulin K40 deacetylases HDAC6 andSIRT2. COS7 cells transfected with A) mCit-HDAC6 or B) mCitSIRT2 were fixed and stained with monoclonal 6-11B-1 (red) and total tubulin (magenta) antibodies. Scale bars, 20 mm. Transfected cells are indicated by a yellow dotted outline. Previous work showed that expression of HDAC6 or SIRT2 in mammalian cells resulted in a complete loss of 6-11B-1 staining [1?], suggesting that the 6-11B-1 antibody does not recognize deacetylated atubulin. In contrast, we show in Figure 4 that moderate expression of HDAC6 or SIRT2 results in deacetylated microtubules that can still be recognized by the 6-11B-1 antibody. To explain the difference between our results and the previous work, we looked at 6-11B-1 and anti-acetyl-K40 labeling at different levels of deacetylase expression. Figure 5 shows cells expressing moderate levels of HDAC6 and SIRT2 expression (based on fluorescence intensity) whereas this figure shows cells expressing high levels of HDAC6 and SIRT2. In agreement with previous work [1?], this figure shows that 6-11B-1 antigenicity is lost in cells expressing high levels of HDAC6 or SIRT2 enzymes. 24272870 The fact that the polyclonal anti-acetyl-K40 antibody does not recognize any microtubules even in cells expressing moderate levels of HDAC6 or SIRT2 enzymes (Figures 5B), indicates that expression of these deacetylase enzymes results in microtubules that are fully nonacetylated (deacetylated and unacetylated). The fact that 6-11B-1 stains microtubules in cells expressing moderate levels of HDAC6 or SIRT2 (Figure 5A) but not high levels of the enzymes (Figure S5) indicates that a-tubulin subunits undergo a structural conversion from the deacetylated (recognized by 6-11B-1) to non-acetylated (not recognized by 6-11B-1) state. Whether this conversion is due to increased levels or time of deacetylase expression is presently unclear. 1. North BJ, Marshall BL, Borra MT, Denu JM, Verdin E (2003) The human Sir2 ortholog, SIRT2, is an NAD(+)-dependent tubulin deacetylase. Mol Cell 11: 437-444. 2. Matsuyama A, Shimazu T, Sumida Y, Saito A, Yoshimatsu Y, et al. (2002) In vivo destabilization of dynamic microtubules by HDAC6-mediated deacetylation. EMBO J 21: 6820?831. 3. Zhang Y, Li N, Caron C, Matthias G, Hess D, et al. (2003) HDAC-6 interacts with and deacetylates tubulin and microtubules in vivo. EMBO J 22: 1168?179. (TIF)Figure S6 HDAC6 or SIRT2 binding does not create an epitope for the 6-11B-1 antibody in PtK2 cells. PtK2 cells expressing the deacetylases mCit-HDAC6 or mCit-SIRT2 (green) were fixed and double stained using monoclonal 6-11B-1 antiacetylated tubulin (red) and total tubulin (magenta) antibodies. Transfected cells are indicated by the yellow dotted outline. Scale bars, 20 mm. (TIF)Author ContributionsConceived and designed the experiments: VS JFH GS KJV. Performed the experiments: VS JFH. Analyzed the data: VS JFH GS KJV. Contributed reagents/materials/analysis tools: VS JFH GS KJV. Wrote the paper: VS J.