As the monoclonal 6-11B-1 antibody recognizes the structurally distinct state of acetylated and Peptide M deacetylated a-tubulin in native microtubules. A structurally distinct state for the K40-containing loop could have important functional consequences on microtubule stability, bending, and interactions. In support of this, differences in lateral protofilament interactions between acetylated and unacetylated microtubules invivo were recently reported [12,13]. Higher resolution cryo-EM studies of unacetylated, acetylated and deacetylated tubulins may help to reveal the structural consequences of this and other modifications.Materials and Methods Antibodies and plasmidsPolyclonal antibody production was carried out by ProteinTech Group and the entire study was approved by their Institutional Animal Care and Use Committee (IACUC). All animals were observed on a regular basis for tissue necrosis and abscess formation at the inoculation sites and for the animal’s activity, food consumption and body condition. Euthanasia was done under anesthetics with ether with cardiac puncture. Rabbits were immunized with a synthetic peptide (amino acids QMPSD[AcK]TIGG common to all mouse a-tubulin isotypes) coupled to keyhole limpet hemocyanin and boosted at separate locations with the same peptide coupled to BSA. Production bleeds were obtained from the ear vein of sedated rabbits with a 21 gaugeCryo-EM Localization of Acetyl-K40 on Microtubulesneedle. Specific antibodies were affinity purified by adsorption to the same peptide coupled to a Sulfolink column (Pierce). The following monoclonal antibodies were purchased: antiacetylated tubulin clone 6-11B-1 ([5] Sigma T7451), anti-a-tubulin clone DM1A (Sigma T6199), and anti-b-tubulin clone E7 (Developmental Studies Hybridoma Bank). Secondary antibodies conjugated to fluorophores were purchased from Jackson 79983-71-4 ImmunoResearch Laboratories. Plasmids for expression of GSTMEC-17 ([23], gift of Jacek Gaertig, University of Georgia), pHEX-His-SIRT2 ([26], gift of Eric Verdin, UCSF) and HAHDAC6 ([45], gift of Xiang-Jiao Yang, McGill University) have been described. MEC-17, HDAC6 and SIRT2 were sub-cloned by PCR into pmCitrine-C1 for mammalian expression.Kinesin binding assayConstitutively active rat kinesin heavy chain (KIF5C) constructs were expressed in COS-7 cells. The cells were lysed in lysis buffer (25 mM HEPES/KOH pH-7.4, 115 mM KOAc, 5 mM NaOAc, 5 mM MgCl2, 0.5 mM EGTA and 1 Triton X-100) containing 0.1 mM ATP and clarified by centrifugation at 14,000 rpm for 10 min at 4uC. Taxol-stabilized acetylated or deacetylated microtubules were added to 0.1 mg/ml together with 20 mM taxol and 1 mM AMPPNP (a non-hydrolyzable ATP analog) and incubated for 30 min at room temperature with constant mixing. The motor-microtubule complexes were sedimented at 90,000 rpm at 18uC for 10 min through a glycerol cushion (BRB80 containing 60 glycerol and 20 mM taxol). The pellet was dissolved in SDS-PAGE sample buffer and the amount of tubulins and motors in the pellets was determined by immunoblotting. The scanned blots were used for quantification in ImageJ software.Mammalian cell culture and ImmunofluorescenceCOS7 (monkey kidney fibroblast, ATCC) cells were grown in DMEM+10 fetal bovine serum (FBS) and 2 mM L-glutamine at 37uC with 5 CO2. PtK2 (rat kangaroo kidney epithelial, ATCC) cells were grown in EMEM+10 FBS and 2 mM L-glutamine at 37uC with 5 CO2. COS7 and PtK2 cells were transfected using Expressfect (Danville Scientific) a.As the monoclonal 6-11B-1 antibody recognizes the structurally distinct state of acetylated and deacetylated a-tubulin in native microtubules. A structurally distinct state for the K40-containing loop could have important functional consequences on microtubule stability, bending, and interactions. In support of this, differences in lateral protofilament interactions between acetylated and unacetylated microtubules invivo were recently reported [12,13]. Higher resolution cryo-EM studies of unacetylated, acetylated and deacetylated tubulins may help to reveal the structural consequences of this and other modifications.Materials and Methods Antibodies and plasmidsPolyclonal antibody production was carried out by ProteinTech Group and the entire study was approved by their Institutional Animal Care and Use Committee (IACUC). All animals were observed on a regular basis for tissue necrosis and abscess formation at the inoculation sites and for the animal’s activity, food consumption and body condition. Euthanasia was done under anesthetics with ether with cardiac puncture. Rabbits were immunized with a synthetic peptide (amino acids QMPSD[AcK]TIGG common to all mouse a-tubulin isotypes) coupled to keyhole limpet hemocyanin and boosted at separate locations with the same peptide coupled to BSA. Production bleeds were obtained from the ear vein of sedated rabbits with a 21 gaugeCryo-EM Localization of Acetyl-K40 on Microtubulesneedle. Specific antibodies were affinity purified by adsorption to the same peptide coupled to a Sulfolink column (Pierce). The following monoclonal antibodies were purchased: antiacetylated tubulin clone 6-11B-1 ([5] Sigma T7451), anti-a-tubulin clone DM1A (Sigma T6199), and anti-b-tubulin clone E7 (Developmental Studies Hybridoma Bank). Secondary antibodies conjugated to fluorophores were purchased from Jackson ImmunoResearch Laboratories. Plasmids for expression of GSTMEC-17 ([23], gift of Jacek Gaertig, University of Georgia), pHEX-His-SIRT2 ([26], gift of Eric Verdin, UCSF) and HAHDAC6 ([45], gift of Xiang-Jiao Yang, McGill University) have been described. MEC-17, HDAC6 and SIRT2 were sub-cloned by PCR into pmCitrine-C1 for mammalian expression.Kinesin binding assayConstitutively active rat kinesin heavy chain (KIF5C) constructs were expressed in COS-7 cells. The cells were lysed in lysis buffer (25 mM HEPES/KOH pH-7.4, 115 mM KOAc, 5 mM NaOAc, 5 mM MgCl2, 0.5 mM EGTA and 1 Triton X-100) containing 0.1 mM ATP and clarified by centrifugation at 14,000 rpm for 10 min at 4uC. Taxol-stabilized acetylated or deacetylated microtubules were added to 0.1 mg/ml together with 20 mM taxol and 1 mM AMPPNP (a non-hydrolyzable ATP analog) and incubated for 30 min at room temperature with constant mixing. The motor-microtubule complexes were sedimented at 90,000 rpm at 18uC for 10 min through a glycerol cushion (BRB80 containing 60 glycerol and 20 mM taxol). The pellet was dissolved in SDS-PAGE sample buffer and the amount of tubulins and motors in the pellets was determined by immunoblotting. The scanned blots were used for quantification in ImageJ software.Mammalian cell culture and ImmunofluorescenceCOS7 (monkey kidney fibroblast, ATCC) cells were grown in DMEM+10 fetal bovine serum (FBS) and 2 mM L-glutamine at 37uC with 5 CO2. PtK2 (rat kangaroo kidney epithelial, ATCC) cells were grown in EMEM+10 FBS and 2 mM L-glutamine at 37uC with 5 CO2. COS7 and PtK2 cells were transfected using Expressfect (Danville Scientific) a.
