Carlos A. Amezcua
NMRVIEW: AdvancedTopics in Protein NMRAnalysis
Carlos AmezcuaUniversity of Texas
Southwestern Medical Center at Dallas
Carlos A. Amezcua
Presentation Outline
n Introduction to STAR Files
n Backbone Assignments: CBCA Window
n Chemical Shift Index Analysis
n Titration and Screening Analysis
n Rate Analysis
Carlos A. Amezcua
STAR FILES
Carlos A. Amezcua
STAR Files: NMRView’s “Notebook”
n STAR (Self-defining Text Archive and Retrieval) files:universal archive files suitable for archiving all types oftext and numerical data in any order.
n The ASCII format allows them to be easily modified byany text editor.
n Currently used by BioMagResBank to store data frombiomolecular NMR spectroscopy (chemical shifts,coupling constants, dihedral angles, etc.).
Carlos A. Amezcua
Common Information Stored byNMRView’s STAR Files
n Molecule’s Data
n Sequence
n Chemical ShiftAssignments
n Peak lists
n 3D Structures
•NMRView is able to keepchemical shifts tables andpeak lists as individual files.
•Keeping a STAR file makesit easy to deposit data intoBMRB. NMRView can alsoread BMRB STAR files.
Carlos A. Amezcua
Format of NMRView’s STAR Files
data_defaultsave_hpask_Saveframe_category monomeric_polymer_Mol_type polymer_Mol_polymer_class protein_Name_common @_Name_variant @_Abbreviation_common @_Name_CAS @_CAS_registry_number @_Enzyme_commission_number @_Molecular_mass 12646.7_Details @_Sequence_citation_label @_Ambiguous_sequence_features @_Residue_count 114_Mol_residue_sequence @_Template_source seq_Template_filename hpask.seq
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loop__Residue_seq_code_Residue_author_seq_code_Insertion_code_Residue_label_Segment_definition_code
1 1 . GLY .2 2 . ALA .3 3 . MET ....111 111 . PRO .112 112 . VAL .113 113 . GLU .114 114 . ARG .
stop_
save_save_Peak_Lists_Saveframe_category peak_lists
loop__Peaklist_name_Peaklist_label hnco 'H1 C13 N15 ' hncacb 'H1 C13 N15 ' cbcaconh 'H1 C13 N15 ' cconnh 'H1 C13 N15 ' hcconnh 'H1 H1b N15 ' hsqc 'H1 N15 ' hcchtocsy 'H1 H1b C13 ' noesy-hsqc15N 'H1 H1b N15 ’
stop_
Repetitive information is stored inthe form of loops
Carlos A. Amezcua
save_save_spectral_peak_list_hnco_Saveframe_category spectral_peak_list_Details ' @'_Software_label @_Experiment_label @_Number_of_spectral_dimensions @_Sample_label @_Sample_conditions_label @_Text_data_format @_Text_data ' @ '_Peaklist_dataset simnoe_Peaklist_scale 1.000000loop_ _Peaklist_label _Peaklist_dim _Peaklist_sw _Peaklist_sf _Peaklist_pattern _Peaklist_relation _Peaklist_idtol
H1 0 4738.21 599.6700 i.hn . 0.0500C13 1 1210.00 150.8120 i-1.c . 0.3000N15 2 1600.00 60.7710 i.n . 0.3000stop_
loop_ _Peak_list_number _Intensity_height _Intensity_volume _Intensity_volume2 _Peak_status _flag _comment _Dim_1_label _Dim_1_chem_shift _Dim_1_line_width _Dim_1_bounds _Dim_1_error _Dim_1_j _Dim_1_link0 _Dim_1_link1 _Dim_1_thread _Dim_1_user _Dim_2_label . . _Dim_3_label . . 0 22.102 0.000 0.000 0 2 {?}{22.HN} 9.402 0.135 0.104 {++} 0.000 0 0 0 {?}{21.C} 175.703 0.198 0.178 {++} 0.000 0 0 0 {?}{22.N} 130.096 0.288 1.031 {++} 0.000 0 0 0 {?} . . .stop_
Peak lists are conveniently storedin the STAR file
Carlos A. Amezcua
How to start a STAR File?
n Load your sequence:
n Save the STAR File
Carlos A. Amezcua
The CBCA Window
A semi-automated tool forbackbone assignments
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Triple Resonance Experiments forBackbone Assignment
CBCA(CO)NH HNCACB
i-1 i
i-1 i 1H (ppm)
13C
(ppm
)
Res i-1, Cb
Res i-1, Ca
Res i, Cb
Res i, Ca
Carlos A. Amezcua
Assignment overview
n Match “clusters”: Linkclusters with common 13Cchemical shifts.
… Clust 4 --- Clust 22 --- Clust 50 …
n Match fragments intosequence:Search for unique chemicalshift patterns (e.g. 13Ca/13Cb)
K T TClust 4 Clust 22 Clust 50
Cluster Peaks 1 A1,A2,B40,B41,B42,B43 2 A8,A9,B25,B26,B27,B28 3 . 4 .
n Generate “clusters”:Cluster peaks from multipleexperiments using common15N/1H shifts.
Carlos A. Amezcua
The CBCA Analysis Step by Stepn Setup CBCA analysis preferencesn Clean and verify peaksn Filter peaks to eliminate artifactsn Cluster peaks based on common HN and N frequenciesn Verify and adjust peak clustersn Link clusters based on common CB and CA frequenciesn Confirm best cluster linksn Transfer chemical shifts to database
Under Developmentn Form fragments which are a series of overlapping clustersn Assign fragments to specific ranges of residues in sequence
Carlos A. Amezcua
Starting a CBCA Analysis
CBCA Window
Main Menu
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Setting up Preferences
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Examining the peaks13
C (p
pm)
15N (ppm) 15N (ppm)1H (ppm) 1H (ppm)
CBCA(CO)NH HNCACB HNCACBCBCA(CO)NH
Peak No.
Carlos A. Amezcua
Example of Multiple Rows
HNCA HNCAHN(CO)CA HN(CO)CA
CBCA(CO)NH CBCA(CO)NH HNCACB HNCACB
15N (ppm) 15N (ppm)1H (ppm) 1H (ppm)
13C
(ppm
)13
C (p
pm)
Carlos A. Amezcua
Filtering and Clustering Peaks
•Peaks are clustered based oncommon HN and N frequencies.
•This algorithm creates a Tcl arraycalled “Clust” that isn’t saved intothe STAR file database. Important:Save as text file using File --> Save
•It is possible to filter peaks bycomparing shifts using referencespectra like 15N/1H-HSQC orHNCO. This process eliminatesartifacts.
Carlos A. Amezcua
Editing Clusters
•Peaks can be shifted from one cluster to another by superimposing the cursor on the desiredpeak and typing the hot key “s”.
•Remember to “Relink” after modifying the cluster and to SAVE OFTEN.
CBCA(CO)NHCBCA(CO)NH HNCACB HNCACB
13C
(ppm
)
15N (ppm) 15N (ppm)1H (ppm) 1H (ppm)
Cluster No.
Carlos A. Amezcua
Matching Clusters•First setup the appropriate “MatchScript”(MatchCA, MatchCBCA2 orMatchCBCA4) and “MatchLists” in thecbcaPrefs window. It is easy to writescripts for other experiments.
•Next, link the clusters based on commonCa and Cb frequencies.
Carlos A. Amezcua
Editing Matching Clusters
Ca/Cb (i-1)N/H (i)
13C
(ppm
)
1H (ppm) 1H (ppm)1H (ppm)1H (ppm)
Ca/Cb (i-1, i)N/H (i)
Ca/Cb (i-2,i-1)N/H (i-1)
Ca/Cb (i)N/H (i+1)
Carlos A. Amezcua
The cbca Control Panel
MatchingCluster
MatchingScore (0-3)
Confirmed: 1Not confirmed: 0
No. of MatchingCarbons
Best match formatching cluster
ConfirmedCluster No.
(not confirmed: -1)
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Matching Clusters to Sequence
Sequence: . . . A139 K140 T141 T142 E143 . . .Cluster No.: …, 121, 104, 38, …
T142T142T141 E143 AA CA CBALA 53.0 18.8SER 58.5 63.8THR 61.9 69.5LYS 56.8 32.8GLU 57.4 30.0GLY 45.2 ----
Chemical ShiftTables (BMRB)
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Transfer of Chemical Shifts tothe Assign Panel
•Using the identified cluster/residue pairs,transfer the chemical shift information to theassign panel.
•This process can be done manually orautomatically through home made macros.
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Secondary StructureInformation from BackboneAssignments
The Chemical Shift Index
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Sequence Display
Sequence Display Window
Main Menu
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Secondary Structure Informationfrom Backbone Chemical Shifts
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Graphical Display of SecondaryStructure Elements on Sequence
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Titration and ScreeningWindows
For these and other Tcl scripts check:
http://freedom7.swmed.edu/NMRview/index.html
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Titration Experiments
• This 15N/1H-HSQC experimentshows a titration of a smallmolecule into a protein solution.
• A computer assisted method isneeded to follow the movingpeaks, record their chemicalshifts and obtain an average KD.
1H (ppm)
15N
(ppm
)
Carlos A. Amezcua
The Titration AnalysisWindow
n Automatically identifies and links shifting peaksof an HSQC titration series.
n Permits manual editing of linked peaks.
n Calculates equilibrium dissociation constants (KD)through an interface with GRACE.
n Written by Brad Holmes and Dr. Kevin Gardner.
Carlos A. Amezcua
A Typical Titration Session
• Load datasets and reference peak list
• Open the titration window
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•Select the reference dataset: “Dataset for enumeration”
•Click on “Draw” and adjust the contour level
•Place a cursor box around the desired spectral region and clickon “PickAll”
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• NMRView automatically pick peaks and generates peak lists forevery dataset.
Carlos A. Amezcua
• To link the shifting peaks click on the “Link Peaks” button
Carlos A. Amezcua
•A very useful tool to keep track of where the peaks are movingto can be accessed with the “DrawBoxes’ button.
Carlos A. Amezcua
Modifying Linked Peaks
• Position the cursor on top of the desired peak and click the“Find” button under the corresponding peak list.
Carlos A. Amezcua
• After selecting peaks for the new vector, click on “DrawBoxes”to see the new direction of the moving peak.
Carlos A. Amezcua
KD Determination
• After inspecting the peaks, fill in the ligand concentration fora given dataset, the protein concentration and click on“Calculate KDs”.
Carlos A. Amezcua
Interface to Grace for Data Fitting•The interface with GRACE calculates a fit for every shiftingpeak above the threshold level and outputs an averaged KD inthe NMRView Tk Console.
Fitting Equation:
Dd = Ddmax *{(L+PT+Kd)- [(L+PT+Kd)2-(4*L*PT)]1/2}
[2*PT]L = Ligand concentrationPT = Total ligand concentrationKd = Equilibrium dissociation constantDd = Chemical shift change at ligand concentration LDdmax = Chemical shift change at saturation
Carlos A. Amezcua
Tools for Ligand Discovery
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Screening Generates Lots of Data
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Dataset Sum Average Max Peaks Gamma ratio: 0.101example-103 5.458 0.012 0.139 445example-140 5.157 0.013 0.128 396example-54 5.009 0.005 0.146 951example-113 4.857 0.010 0.120 488example-26 4.770 0.010 0.134 477example-129 4.757 0.009 0.123 521example-148 4.620 0.008 0.130 561example-119 4.593 0.009 0.106 512example-135 4.422 0.008 0.142 533example-23 4.404 0.011 0.135 383example-61 4.402 0.005 0.118 826example-99 4.330 0.005 0.112 956
Output File: Ranking of spectra by sum of minimum chemical shifts
The Screening Window
•This new tool allows to rapidlypeak pick many spectra andcalculates minimum chemicalshifts (mcs) with respect to areference.
•mcs = sqrt{(dref-d)2H + [(dref-d)
*(gHET/gH)]2HET}
Carlos A. Amezcua
Rate Analysis
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Typical Experiments
n Relaxation experiments: T1, T2
n Chemical exchange: N-H ---> N-D
n Slow conformational changes
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The Rate Analysis Window•Open datasets and read the peak list
•Type the “Matrix Root”, “Matrix Extension”, Noise “SDev”, and select the control “Peaklist”
•Click on “Setup” and select the file with the “Extensions and Delays”
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Selecting Fitting Parameters
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Fitting Results
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Output files
filename.txtPeak No. Residue Average Value Maximum Minimum Std. Dev.relax.0 213.HN 628.234152 640.609113 615.592839 0.322123relax.1 230.HN 627.522038 640.356408 616.455145 0.480259relax.2 137.HN 640.591471 651.978668 629.362775 0.437270relax.3 145.HN 639.115880 657.254495 624.447290 0.233065relax.4 135.HN 657.214250 675.046681 641.816510 0.310350relax.5 211.HN 699.213025 711.432576 689.888055 0.492043
filename.datRes T1(s) Err(max) Err(min)213 0.628234152 0.012641313 0.012374961230 0.627522038 0.011066893 0.01283437137 0.640591471 0.011228696 0.011387197145 0.63911588 0.01466859 0.018138615135 0.65721425 0.01539774 0.017832431211 0.699213025 0.00932497 0.012219551
• File in GRACE format
• GRACE plot
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HetNOE Analysis andWrite Modelfree
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Heteronuclear NOE Analysis
Output FilePeak Res NOE Errorhsqc.0 90.HN 0.844579727153 0.0220038139944hsqc.1 107.HN 0.765441512887 0.0228763153881hsqc.2 14.HN 0.65637966805 0.0194502074689hsqc.3 22.HN 0.757088658147 0.0299520766773hsqc.4 12.HN 0.749387683695 0.0262421273618hsqc.5 88.HN 0.720154882832 0.0150859901438
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MODELFREEInterface
•This window helps to generate inputfiles to be used with Art Palmer’sModelfree4 program (for 15N-relaxationanalysis).(http://cpmcnet.columbia.edu/dept/gsas/biochem/labs/palmer/software.html)
•Requires T1and T2 files generatedthrough the Rate Analysis window andNOE files generated with the HetNOEAnalysis window.
Carlos A. Amezcua
Good Luck andHappy Analysis
Acknowledgements:ÿKevin Gardner
ÿBrad Holmes
ÿJohn Shriver
ÿRenee Valentine