Immunoblotting

StatisticalAnalysis

Somatotype Dispersion Distances (SDD)

f. 5 μl of water was then spotted on each spot for 30 sec and removed using Whatman filter paper strips. This step was repeated once. g. 1-2 μl of SAP matrix was then applied to each spot and allowed to dry. h. The chip was then placed in the SELDI machine

a. 5 μl of 10 mM HCl was added to each spot on the chip and removed after 5 min. using Whatman filter paper strips. b. Washing was given by spotting 3 μl of water for 30 sec on each spot followed by removal using Whatman filter paper strips. This step was repeated two times. c. 10 μl of low stringency/ high stringency buffer was then added to the spot and kept in humid chamber for 5 min. followed by removal using Whatman filter paper strips. d. 3 μl of sample prepared in low stringency/ high stringency buffer was then added to the spot and incubated in humid chamber for 30 min. e. Washed the spot with 5 μl of low stringency buffer/ high stringency buffer/ buffer of pH 3.0/ pH 5.0/ pH 7.0 for 30 sec and removed using Whatman filter paper strips. This step was repeated five times.

Activation of CM10 (weak cation exchange ) array

d. 3 μl of sample prepared in low stringency buffer was added to the spot activated with low stringency buffer and incubated in humid chamber for 30 min. and removed using whatman strips. (same protocol was repeated for the samples prepared in high stringency buffer on spots activated with high stringency buffer). e. Stringent washings were given to each spot with 5 μl of low stringency buffer/ high stringency buffer/ buffer of pH 3.0/ pH 5.0/ pH7.0 for 30 sec and removed using Whatman filter paper strips. f. 1-2 μl of SAP matrix was added to each spot and allowed to dry. g. The chip was then placed in the SELDI machine

One set of cell extracts was prepared in low stringency buffer by mixing cell extracts and low stringency buffet in 1:1 ratio and another in high stringency buffer. b. 10 μl of low stringency/high stringency buffer was added to the spots on the chip and incubated in a humid chamber for 5 min. c. Buffer was removed using Whatman strips without touching the spot surface. This step was repeated once

Activation of LSAX (strong anion exchange ) array

Activation of H50 protein chip array

b. 5 μl of ACN + TFA (25% ACN in PBS + 0.1% TFA) was added to the spot surface and removed after 30 sec. c. 5 μl of cell lysate sample was then spotted on the chip and kept in a humid chamber for 30 min. d. Stringent washes were given by spotting 5 μl water on the spot surface for 30 sec and removing using Whatman filter paper strips. This was followed with a 25% ACN wash or three washes with 25% ACN or 50% CAN or 75% ACN. e. Washing was performed by spotting 5 μl of water for 30 sec followed by removal using Whatman filter paper strips. f. Dried chip at room temperature. g. 1-2 μl of SAP matrix (5 mg of matrix + 200 μl ACN + 200 μl of 1% TFA) was then spotted on the chip surface and allowed to dry. h. The chip was then placed in the SELDI machine

5 μl of water was added to each spot on the chip and removed after 30 sec using Whatman filter paper strips. Care was taken not to touch the spot surface. This step was repeated once

5 μl of 0.1% TFA was applied to the spots on the SEND array and removed after 30 sec using Whatman paper (care was taken not to touch the spot surface). b. 5 μl of cell lysate sample was spotted on the SEND array and incubated in a humid chamber for 10 min. Removed after 30 min. c. 5 μl of 0.1% TFA was then added and removed after 30 sec. d. 2 μl of 25% ACN in 0.1% TFA was added to the spots and allowed to dry. e. The chip was then placed in the SELDI machine

Activation of SEND arrays for peptide analysis

Trypsinization: The decolourized bands were dried in a vacuum dryer for 1 hr until the gel pieces were completely dry. 5 μl of 0.1 μg/μl trypsin and 25 μl of 25 mM NH4HCO3 (pH 8.0) were then added to the dried gel pieces. The tubes were sealed with parafilm and kept in a water bath at 37 ̊C, overnight. Care was taken that the gel pieces in the tubes did not dry up. If the gel pieces got dried, 25 μl of NH4HCO3 was added on top. Peptide extraction: A 1:1 mixture of ACN:5% TFA in water was added (30 μl) to overnight tryptic digests and kept for 30 min. The elutant was removed in a separate low binding tube. The extraction step was repeated once more. The elutant was then dried in a vacuum dryer (1-2 hr) and reconstituted in 5 μl of 25% ACN in 0.1% TFA

Destaining of gel bands: The protein bands of differentially expressed proteins were cut out from the gel and put in low binding microfuge tubes. 150 μl of 50:50 Acetonitrile:Ammonium bi carbonate pH 8.0 (NH4HCO3) was then added and kept under shaking for 30 min. Coloured liquid was discarded and the washing step repeated until the bands decolourised

Destaining of gel, trypsinization and peptide extraction

12% resolving gel (for 25 ml)Water = 8.2 ml 30% Acrylamide = 10.0 ml 1.5 mM Tris (pH 8.8) = 6.3 ml 10% SDS = 0.25 ml 10% APS = 0.25 ml TEMED = 0.01 ml 5% stacking gel (for 10 ml)Water = 6.8 ml 30% Acrylamide = 1.7 ml 1.5 mM Tris (pH 6.8) = 1.25 ml 10% SDS = 0.1 ml 10% APS = 0.1 ml TEMED = 0.01 ml

A double cylinder gradient former was used with 12% poly acrylamide gel mix in the inner cylinder and a 3% polyacrylamide gel mix in the outer cylinder that was stirred using a magnetic bead on a magnetic stirrer. A pump was connected to the flow tube and the flow rate adjusted at 5-8 to cast a 12-3% gradient gel. A 5% stacking gel was used. After the protein samples were run on the gradient gel, it was stained in instant blue over night under shaking. 3% resolving gel (for 25 ml)Water = 15.68 ml 30% Acrylamide = 2.5 ml 1.5 mM Tris (pH 8.8) = 6.3 ml 10% SDS = 0.25 ml 10% APS = 0.25 ml TEMED = 0.02 ml

Casting a gradient SDS-polyacrylamide gel

1μl of the cell lysate was mixed with 200 μl of 5X Bradford reagent and 800 μl of water. O.D was measured at 595 nm. Standard curve of BSA was plotted using various dilutions of BSA protein by Bradford method. Protein estimation of the cell lysate samples was performed using the standard curve equation y=0.0695x + 0.0329 μg/μl

Protein estimation by Bradford method

microfuge tubes and snap frozen in liquid nitrogen and were stored at ─80 ̊C. Protein estimation was performed simultaneously with one of these aliquots

The strains were grown to stationary phase in 500 ml LB supplemented with ampicillin (100 μg/ml) overnight. Cells were pelleted at 2100g for 30 min at 4 ̊C and dissolved in 5 ml of 1X PBS with 2X protease inhibitor and 3 mM DTT. Cells were lysed using French Press at 1500 psi for three cycles. The lysed cells were pelleted at 20,000g for 45 min at 4 ̊C. Clear supernatant was collected in sterile 2 ml

Preparation of cell extracts

These experiments were undertaken in the laboratories of Dr. Sylvie Rimsky and Dr. Malcolm Buckle at the Ecole Normale Superioure, Cachan, Paris (France)

Methods for SELDI (Surface Enhanced Laser Desorption/Ionization)

the membrane and sandwiched between 1 piece of buffer-soaked Whatman paper from Biorad on each side. The sandwich was placed between graphite electrodes with the membrane towards the anode. The transfer was done for 12-16 hr using a voltage of 40 V in the cold room. Protein transfer was viwed using Ponceau S staining. Blot was dipped in the Ponceau S stain under shaking and washed using PBST. After transfer, the membrane was blocked with 5% non-fat milk in PBST (1X PBS with 0.1% Tween-20) for 2 hr at room temperature. The membrane was then washed thrice with PBST under shaking and incubated with the primary antibody (1:1000 dilution in PBST) for 12-16 hr. The membrane was again washed thrice under shaking with PBST and incubated with 1:20000 dilution alkaline phosphatase conjugated anti-goat IgG secondary antibody (in PBST) for 2 hr. The membrane was once again washed thrice as described above and the signal developed using ECL kit from Amersham on X-ray films in a dark room. The reactive protein bands appeared as black bands upon gentle shaking at room temperature in 1X developer solution. The reaction was stopped by dipping and shaking the film in 1X Fixer solution followed by washing in water

The protein samples separated on SDS-PAGE were transferred to PVDF (polyvinyledene difluoride) membrane (Amersham, Buckinghamshire, UK) electrophoretically by a semi-dry method using BioRad apparatus. The gel and the membrane (pre-wetted with methanol) were wetted with transfer and the gel was placed in contact with

Western blotting with anti-Rho/anti-NusG antibody

(ii) Stacking gel buffer: 1.0 M Tris-Cl pH 6.8 (iii) Resolving gel buffer: 1.5 M Tris-Cl pH 8.8 (iv) SDS stock: 10% (w/v) solution (v) Ammonium persulphate (APS) stock: 10% (w/v) solution made fresh (vi) Gel running buffer (1X) (vii) Loading dye (6X): (viii) Lysis buffer (RIPA) Gels of 1.5 mm thickness were cast in the Biorad small gel apparatus. Resolving gel of 10% (10 ml) was made by mixing 4.2 ml 10% acrylamide, 3.1 ml water, 2.5 ml of 1.5 M Tris-Cl pH 8.8 and 0.1 ml of 10% SDS. Stacking gel (2 ml) was made by mixing 0.33 ml of 30% acrylamide, 1.4 ml of water, 0.25 ml of 1 M Tris-Cl pH 6.8 and 0.02 ml of 10% SDS. Gels were polymerized by the addition of TEMED (N,N,N′, N′-tetramethyl ethylene diamine) and APS (1/100th volume of gel mix). Sample preparation for gel loading was done as follows. Mid log and late log phase 10 ml cultures were centrifuged at 26000g and the cell pellet was resuspended in 0.5 ml RIPA buffer. Cells were sonicated on ice for 1 min at output power of 5 to get a cleared lysate. The culture lysate was centrifuged at 26000g to recover the clear supernatant. Total cell protein was quantified in the lysates using BCA kit reagents (BioRad) using the manufacturers protocol. Appropriate volume of cell lysate was mixed with the loading dye in a final concentration of 1X and loaded onto the gel. The gel was run at constant voltage of 60 V for stacking and 80 V for resolving gel

The method followed was as described in Sambrook and Russell (2001). The following solutions were used to cast and run SDS-PAGE gels. (i) Acrylamide stock: 29% (w/v) acrylamide and 1% N,N′-methylene bisacrylamide

Sodium dodecyl sulphate-polyacrlyamide gel electrophoresis (SDS-PAGE)

Automated DNA sequencing on plasmid templates or on PCR products was carried out with dye terminator cycle sequencing kits on an automated sequencer following the manufacturer's instructions by either CDFD or an outsourced sequencing facility

DNA sequencing

Inverse PCR is a technique to amplify unknown regions flanking the site of transposon insertion using the primers designed from the known sequence from one end of the transposon element. Genomic DNA was digested with a 4-base recognition restriction enzyme, Sau3A1 followed by intramolecular ligation set up at high dilutions. These ligated molecules were then used as templates for the PCR performed with a pair of divergently-oriented primers designed from one end of the transposon named AH1-AH2. The PCR product thus obtained was sequenced with the same set of primers to identify the junction sequence at the site of transposon insertion and hence the identity of the gene disrupted in each case. Typical PCR conditions used were as follows:- Annealing 55°C 2 min Elongation 72°C (1 min/kb of DNA template to be amplified) Denaturation 95°C 2 min After 30 cycles of PCR, the final elongation step was carried out again for 10 min at 72°C

Inverse PCR

Denaturation 95°C 1 min After 30 cycles of PCR, the final elongation step was carried out again for 10 min at 72°C

The PCRs were normally performed using a PCR amplification kit from Fermentas/Sigma (USA), following the company's protocols. Approximately, 10 ng of chromosomal or 1-2 ng of plasmid DNA was used as template in a 50 μl reaction volume containing 0.2 mMM of each dNTP, 20 picomoles each of forward and reverse primer and 0.5 units of Taq DNA polymerase. In some cases, freshly streaked E.coli cells from a plate were resuspended in 50 μl of sterile Milli Q water to get a cell suspension (~ 109 cells/ml) and 10 μl from this was used as the source of DNA template. The samples were subjected to 30 cycles of amplification and the typical conditions of PCR were as follows (although there were slight modifications from one set of template/primers to another): The initial denaturation was done at 95°C for 3 min and the cycle conditions were as given below. Annealing 55°C 1 min Elongation 72°C (1 min/kb of DNA template to be amplified)

Polymerase chain reaction (PCR)

Fresh overnight culture of the E. coli strain (DH5α) was subcultured 1:100 in 250 ml LB/SOB media at 18 ̊C and 2500g and allowed to grow to an A600=0.55. Culture was chilled on ice and centrifuged at 2500g at 4 ̊C for 10 min. The cell pellet was redissolved in 80 ml ice-cold Inoue transformation buffer (55 mM MnCl2, 15 mM CaCl2, 250 mM KCl, 10 mM PIPES pH6.7). This cell suspension was centrifuged at 2500g at 4 ̊C for 10 min. and the cell pellet was resuspend in 20ml ice-cold Inoue buffer with 1.5 ml DMSO. This mixture was then placed on ice for 10 min. Aliquots of this suspension were dispensed into chilled, sterile microfuge tubes that were snap-frozen in a bath of liquid nitrogen. Tubes were stored at ─70 ̊C until required. For transformation the cells were thawed on ice and plasmid DNA was added followed by the standard transformation protocol

Preparation of ultracompetent cells

Overnight cell culture raised in LB medium was subcultured 1:100 in LB with 20 mM MgCl2. When the A600 reached 0.4-0.6, the culture was centrifuged at 2800g for 5 min at 4 ̊C. To the cell pellet 0.4 volumes of ice-cold TBF-I buffer was added and incubated on ice for 15 min. The cell suspension was centrifuged at 2800g for 5 min at 4 ̊C and the cells recovered were dissolved in 0.04 volume of ice-cold TBF-II buffer and kept on ice for 45 min. 100 μl aliquots of these competent cells were used for transformation using the normal transformation protocol

TBF method for preparation of high competency cells

For routine plasmid transformations, where high efficiency is not required, the following method which is a modification of that described by Sambrook and Russell (2001) was used. An overnight culture of the recipient strain was subcultured in fresh LB and grown till mid-exponential phase. The culture was chilled on ice for 15 min, and the steps hereafter were done on ice or at 4°C. The culture was centrifuged, and the pellet was resuspended in one third volume of cold 0.1 M CaCl2. After 15 min incubation on ice, the cells were again recovered by centrifugation, and resuspended in one tenth volume of cold 0.1 M CaCl2. The suspension (0.1 ml) was incubated on ice for 1 h after which DNA was added (~10-100 ng of DNA in less than 10 μl volume). The mixture was again incubated on ice for 30 min, and then heat shocked for 90 seconds at 42°C. Immediately 0.9 ml of LB broth was added to the tube and incubated at 37°C for 45 min for phenotypic expression of the antibiotic marker before being plated on selective medium at various dilutions. A negative control tube (with no plasmid DNA addition) was also routinely included in each of the experiments

Calcium chloride method

Transformation protocols

Typically, 100-200 ng of DNA was used in each ligation reaction. The ratio of vector to insert was maintained between 1:3 and 1:5. The reactions were usually done in a 10 μl volume containing ligation buffer (provided by the manufacturer) and 0.05 Weiss units of T4 DNA ligase, at 16°C for 12-16 hr

Ligation of DNA

DNA fragments to be used for ligation were eluted from the agarose gel, after the electrophoresis. The gel piece containing the desired band of DNA was sliced out and the DNA was purified from the gel using the purification kits available for this purpose. The efficiency of elution was determined by checking a small aliquot of DNA sample on the gel

Purification of DNA fragments by elution from the gel

0.5-1 μg of DNA was used for each restriction enzyme digestion. 2-4 units of the restriction enzymes with the appropriate 10X buffers supplied by the manufacturers were used in a total reaction volume of 20 μl. The digestion was allowed to proceed for 6 h or 10min. (for FAST digest enzymes) at the temperature recommended by the manufacturer. The DNA fragments were visualized by ethidium bromide staining following electrophoresis on 1-1.5% agarose gels. Commercially available DNA size markers were run along with the digestion samples to compare with and to estimate the sizes of the restriction fragments

Restriction enzyme digestion and analysis

The DNA samples were mixed with the appropriate volumes of the 6X loading dye (0.25% bromophenol blue, 0.25% xylene cyanol and 30% glycerol in water) and subjected to electrophoresis through 1-1.5% agarose gel in either 1X TBE or 1X TAE buffer. The gel was stained in 1 μg/ml of ethidium bromide solution for 30 min at room temperature and the bands were visualized by fluorescence under UV-light

Agarose gel electrophoresis

Quiagen/HiPura following the manufacturer's protocols

The rapid alkaline lysis method of plasmid isolation, as described by Sambrook and Russel (2001), was followed with minor modifications. Bacterial pellet from 3 ml of stationary-phase culture was resuspended in 200 μl of ice-cold solution I (50 mM glucose, 25 mM Tris-Cl pH 8.0, 10 mM EDTA pH 8.0 containing 1 mg/ml lysozyme) by vortexing. After 5 min incubation at room temperature, 400 μl of freshly prepared solution II (0.2 N NaOH, 1% SDS) was added and the contents were mixed, by gently inverting the tube several times. This was followed by the addition of 300 μl of ice-cold solution III (5 M potassium acetate, pH 4.8) and gentle mixing. The tube was incubated on ice for 5 min and centrifuged at 20,0000g for 15 min at 4°C. The clear supernatant was removed into a fresh tube and, if required, was extracted with an equal volume of phenol:chloroform mixture. The supernatant was precipitated with either two volumes of cold 95% ethanol or 0.6 volumes of isopropanol at room temperature for 30 min. The nucleic acids were pelleted by centrifugation, washed with 70% ethanol, vacuum dried, and dissolved in appropriate volume of TE buffer. If required, the sample was treated for 30 min with DNase free RNase at a final concentration of 20 μg/ml. The plasmid DNA was checked on a 0.8% agarose gel and stored at −20°. The plasmid DNA thus isolated was suitable for procedures such as restriction digestion, ligation, and preparation of radiolabeled probes. Plasmid isolation was also done with any of the commercially available kits from

Isolation of plasmid DNA

and the aqueous phase transferred to a fresh tube. The aqueous phase was further extracted successively, first with phenol:chloroform:isoamyl alcohol (25:24:1) and then with chloroform:isoamyl alcohol (24:1). DNA was precipitated from the clear supernatant by the addition of 0.6 volumes of isopropanol. The chromosomal DNA was either spooled out or pelleted at this stage, washed with 70% ethanol, air-dried, and dissolved in suitable volume of TE buffer

The method as described in the manual Current Protocols in Molecular Biology was followed for preparation of chromosomal DNA. Cells from 1.5 ml stationary phase culture were recovered by centrifugation and resuspended in 567 μl of TE buffer. To this, 30 μl of 10% SDS, and 3 μl of proteinase K (20 mg/ml) were added in that order and the cell suspension mixed and incubated at 37°C for 1 h. Next, when the suspension looked cleared, 100 μl of 5 M NaCl was added, thoroughly mixed, followed by the addition of 80 μl of CTAB/NaCl (10% cetyltrimethylammonium bromide in 7 M NaCl) and vigorous mixing (by inverting the microfuge tube). The suspension was incubated at 65°C for 10 min, brought to room temperature, extracted with an equal volume of chloroform-isoamyl alcohol (24:1 v/v)

Extraction of chromosomal DNA from bacterial cells

Molecular and genetic techniques

For TEM, C. glabrata cells were digested with zymolyase 20T for 3 h at 30◦C, centrifuged at 1,000 g and washed with YPD medium. Cell fixation was performed as described for SEM and dehydrated samples were embedded in araldite 6005 resin. After complete polymerization at 80 ̊C for 72 h, ultra-thin (50-70 nm) sections were preparedwith a glass knife on Leica Ultra cut (UCT-GA-D/E-1/00)microtomeand mounted on copper grids. Aqueous uranyl acetate-stained and Reynolds lead citrate-counterstained samples were viewed under Hitachi H-7500 transmission electron microscope

Transmission electron microscopy

For SEM, C. glabratacells were fixed for 24 h in 2.5% glutaraldehyde in phosphate buffer (0.1 M, pH 7.2) at 4 ̊C, post-fixed in 2% aqueous osmium tetroxide for 4 h and dehydrated. After drying to critical point, mounted samples were coated with a thin layer of gold for 3 min using an automated sputter coater and visualized by SEM (JEOL-JSM 5600)

Scanning electron microscopy

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed at the Electron Microscope Facility, RUSKA LABs, Acharya N. G. Ranga Agricultural University, Hyderabad

Electron Microscopy

For preparing agarose gels,appropriate amount of agarose(0.8-2%) was dissolved by boilingin TAEbuffer, until clear slurry was formed.It wasthen poured in a casting tray containing a comb for desired number of wells. The gel was allowedto solidify andshifted to horizontal electrophoresis tank containing TAE bufferwith 1 μg/ml ethidium bromide. Appropriate volumesof 6X DNA loading dye were added in the samples and subjected to electrophoresis atconstant voltage (generallyat80 V), along with appropriate DNA ladder,untilband were resolved. The gel was visualised underUV-light in a Gel-Doc or UV-transilluminator

Agarose gel electrophoresis

recovery, cells were centrifuged at 2,500x gfor 4 min. The medium supernatant was discarded and cells were resuspended in 200 μLfresh sterile LB medium. Cells were plated on LB agar medium containing appropriate antibiotics. Plates were incubated at 37°C for 12-16 hto allow growh of individual colonies

E. coli DH5α strain was transformed with yeast plasmids carrying appropriate inserts that express S.cerevisiaeproteins (Sambrook and Russell, 2001). Ultracompetent cells stored at -80°C were thawed on ice for 5-10 min. 20μLligated plasmid was added to 100 μLultracompetent cells,and the cells were incubated on ice. After 30 min, competent cells were subjected to heat shock at 42°C for 90 seconds. Cells were immediately transferred to ice for 2-3 min. Next, 900 μLLB medium was added and cells were allowed to recover for 45 min on a shakerincubator set at 37°C. After the

Bacterial transformation

Statistical analysis was performed using GraphPsssad Prism 5. Data are presented as mean ± SEM. The difference between two groups was analyzed using either a two-tailed Student’s t-test or a nonparametric two-tailed Mann-Whitney test, as appropriate. The differences between multiple groups were analyzed by one-way ANOVA, using Tukey’s multiple comparison test for parametric data and Kruskal-Wallis test for non-parametric data. P<0.05 was considered as statistically significant. The cell numbers used to obtain quantitative data (n) and the number of independent experiments performed is indicated in the respective figure legends

Data analysis