Download Creating Multiple Sequence Alignments

BIT150 – Lab3
Sequence Alignment, Multiple Sequence Alignment and Phylogenetics
Copy 10_Lab3 from Z: to C:.
A. SEQUENCE ALIGNMENT
The most basic task in sequence analysis is to ask whether two sequences are similar and
can be compared. Proteins with very similar sequences probably share structural
properties and similar functions.
Objective: Explore different methods of sequence alignment, interpret their results, and
compare them.
A1. Graphical method
Dotter (http://www.cgb.ki.se/cgb/groups/sonnhammer/Dotter.html ): A dot-matrix
program with interactive grayscale for DNA and protein sequence analysis.
 Dotter is preinstalled on your lab computers.
Follow these steps to run Dotter:
1.1. The DNA sequence file WIS.txt to be used with Dotter is in ‘10_Lab3\Dotter
files’. Copy this file into the ‘C:\BIT150\Programs\Dotter’ (an alternative is to write
the PATH of each file when you run the program).
1.2. Dotter needs to be started from the Command Prompt window:
Start-> Programs -> Accessories -> Command Prompt (create a shortcut in your
desktop).
Alternatively, Start -> Run… -> in Open, type cmd -> OK.
This is the old DOS operating system (case insensitive).
1.3. Move to the Dotter directory (located in ‘C:\BIT150\Programs\Dotter’), typing:
call C: -> press Enter;
cd BIT150\Programs\Dotter (to change directory).
To see the files present in the Dotter directory, type dir. Check for WIS.txt and
MITE2.txt.
1.4. Using Dotter, align the DNA sequence of the retroelement WIS, WIS.txt, with
itself to look for internal repeats. To do it, type:
dotter WIS.txt WIS.TXT -> press Enter -> wait….
1.5. Analyze the Dotter output:
 Dotter window: The first sequence runs along the x-axis and the second
sequence along the y-axis. Segments of 25 bp in one sequence (along the X axis) are
compared to segments of 25 bp in the second sequence (Y axis). In regions where the
two sequences are similar to each other, a row of high scores runs diagonally across
the dot matrix.
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o Set width of the sliding window: (right click on the Dotter window and select
‘Change size of sliding window’). The default width of 25 residues over which
the pairwise scores are averaged has proven to be very robust, but you can
change the width of the sliding window.
o Print to a file: (right click on the Dotter window and select ‘Print’). You can
print the alignment to a PostScript file and later convert it to PDF.
 Greyramp Tool window: Generates windows along the diagonals, and draws a
dot in the center of the window only if the sum of the scores of all ‘dots’ within that
window is above the maximum threshold, while dots below the minimum threshold
get the minimum intensity, and dots in between are ‘rendered’ with a grayscale
intensity proportional to their sum of scores. Interactive and dynamic changing of
maximum and minimum thresholds allows the exploration of various signal
stringencies.
 Alignment Tool window: Allows you to see the match that causes a given dot in
the dotplot. Move the crosshair of the Dotter window with the left mouse button to the
dot, and pop up the Alignment Tool. Once in the proximity, use the cursor keys to
move the crosshair one residue at the time.
- Copy and paste the alignment into your Word document (use Shift/PrintScreen to
copy all what you have in your screen, open Start/Programs/Accessories/Paint,
paste the image, select what you want, cut it, and finally paste it into your Word
document).
- After aligning WIS.txt with itself, what type of repeat is present in the sequence?
A2. Dynamic-programming methods
 Global: Needleman-Wunsch algorithm (1981)
 Local: Smith-Waterman algorithm (1970)
>Seq1
ACCAACCATACGAGTATCAGACCTATCAGGCCTATCCAGAGCAGATCATGGACTAACCCTAGGACATACCATCT
>Seq2
ACTAATCATGGACTAACCCCCTAGGACATACCACTACATATGGCCTGATACCTCTGATACTCGTATGGTATCT
2.1. Open the link: http://www.ebi.ac.uk/emboss/align/
Paste Seq1 and Seq2 into the Sequence1 and Sequence2 windows, respectively. Select
DNA as molecule where asked. Compare needle (global) and water (local) alignment
results. For both, use the default settings of Gap 10 Extend 0.5.
NEEDLE - GLOBAL
Seq1
1 ACCAACCATACGAGTATCAGACCTATCAGGCCTATCCAGAGCAGATCATG
.|||
||||||
1 ------------------------------ACTA----------ATCATG
50
74
Seq2
51 GACTAA--CCCTAGGACATACCATCT-----------------------|||||| ||||||||||||||| ||
11 GACTAACCCCCTAGGACATACCA-CTACATATGGCCTGATACCTCTGATA
Seq1
74 --------------
74
Seq2
60 CTCGTATGGTATCT
73
Seq2
Seq1
10
59
WATER - LOCAL
Seq1
Seq2
32 CTATCCAGAGCAGATCATGGACTAA--CCCTAGGACATACCA
|||
|||||||||||| |||||||||||||||
2 CTA----------ATCATGGACTAACCCCCTAGGACATACCA
71
33
2
A3. Words methods (heuristic)
 BLASTN: The Basic Local Alignment Search Tool (BLAST) finds regions of
local similarity between sequences.
3.1. Using BLAST 2 Sequences
(http://www.ncbi.nlm.nih.gov/blast/bl2seq/wblast2.cgi), run the same two sequences,
Seq1 and Seq2 from 1.6. Select blastn as ‘Program’.
- Copy and paste the Dot Matrix View and the
alignment into your Word document.
- What is the orientation of the conserved segments?
- Compare this alignment with those previously
obtained using, needle (global), and water (local).
BLAST is more flexible to find inverted segments!
3.2. Change ‘gap open penalty’ from 5 (default) to 3.
Run.
- Copy and paste the alignment into your Word document (use
Shift/PrintScreen).
- What types of repeats present in the sequences can you identify now?
3.3. Which of the three methods (needle (global), water (local), BLAST 2 Sequences)
detected better the similarities observed in Dotter?
 BLASTX: DNA-protein alignment (protein database using a translated nucleotide
query).
3.4. Using BLAST 2 Sequences, compare the genomic DNA sequence of the Acyl
Co-A Synthetase from Lab1 with the predicted protein sequence. Sequences are in the
file 10_Lab1\Sequin Acyl Co-A Synthetase\ Final annotation.doc. and also in
10_Lab3.
Paste the Acyl Co-A synthetase DNA sequence in the Sequence 1 window and the
Acyl Co-A synthetase protein sequence in the Sequence 2 window. Select blastx as
‘Program’.
- Could you identify the 6 exons?
- Are the borders of the exons as precise as in the flat file prepared using Sequin?
3.5. Change ‘gap extension penalty’ from 1 (default) to 2.
- Can you see any improvement?
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 BLASTP: Comparing two proteins.
3.6. Using BLAST 2 Sequences, align the following sequences. Select blastp as
‘Program’.
>K_transport
VGALLLYLPISTTRPISFLDALFTATSAVTVTGLAVLDTYSDFTLFGKLVILFLIQVGGLGYMTLSTFFLVLLGRRIGLKER
LILAESLEYPSMHGLIRFLKRVFSFVFITELTGAILLSIYFSLKGVEDPVFNGIFHSVSAFNNAGFSTFKNG
>TRK system potassium uptake protein
NDIQTKYALIVTAFISIIISIKDKVPIIDSLFTVVSAMTSTGFTTINVGNLSSLSLFLIIFLMLIGGGAGTTTGGVKIIRFL
VILKALLYEIKEIIYPKSAVIHEHLDDMDLNYRIIREAFVVFFLYCLSSFLTALIFIALGYNPYDSIFDAVSF
- Compare alignments with ‘Matrix’ BLOSUM62/BLOSUM80/
/PAM30/PAM70. Any change when changing matrices?
PAM (Percentage of Acceptable point Mutations per 108 years) matrices
BLOSUM (BLOcks SUbstitution Matrix) matrices
B. Creating Multiple Sequence Alignments (MSA)
Objective: Perform multiple sequence alignments, calculate distance matrices, and
construct phylogenetic trees, to understand and interpret relationships between species.
In this example, we will create a multiple alignment of protein sequences that will be
imported into the alignment editor using different methods. Multiple protein sequence
alignment is a central tool to infer protein function, predict protein secondary structure,
and identify residues important for protein specificity.
Open the file ‘FT proteins for MEGA.doc’.
B1. Start MEGA4 by using Start\Programs\BioInformatics\MEGA4.
B2. In the MEGA4 window, go to Alignment|Alignment Explorer/CLUSTAL. Select
‘Create a new alignment’, and click on OK. Click on [NO] for protein sequence
alignment.
B3. Sequences can be entered either from FASTA files (opening the concatenated
FASTA sequences TXT file using MEGA) or by hand. We will enter the
sequences by hand, one by one. In the Alignment Explorer window, go to
Edit|Insert Blank Sequence or click on
, and repeat it to generate 8 blank
sequences. Right-click on the blank sequence name and edit the sequence name
for each protein sequence, as it is in the Word document ‘FT Proteins for MEGA’.
Copy and paste each sequence.
B4. Go to Edit|Select All to select every site for all the protein sequences in the
alignment.
B5. Go to Alignment|Align by ClustalW or click on
sequences using the ClustalW algorithm.
to align the selected protein
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B6. Save the current alignment by selecting the Data|Save Session. Save it as ‘FT.mas’.
This will allow the current alignment to be restored for future editing. Also,
export it (Data|Export Alignment|FASTA format) as both a FASTA file
(‘FT.fas’) and a MEGA file (‘FT.meg’).
C. Generating a publishable MSA using BoxShade
C1. Using Word, open the previously created FASTA file (‘FT.fas’). Copy the FASTA
sequences (including gaps). Past them in BOXShade:
http://www.ch.embnet.org/software/BOX_form.html. In the ‘Output format’
select RTF_new and in the ‘Input sequence format’ select other. Click on Run
BOXSHADE. Click On ‘here is your output number 1’. The alignment will be
open in a Word document.
D. Exploring the MSA and identifying patterns
D1. Back in MEGA4, exit the Alignment Explorer window by selecting the Data|Exit
AlnExplorer. A dialog box will appear asking you if you would like to open the
data file in MEGA; click on ‘Yes’.
D2. Observe different coloring schemes by clicking on: C: conserved residues (the same
amino acid at a given site in all the aligned sequences), V: variable residues (at
least 2 different amino acids at a given site), Pi: Parsimony informative (at least 2
different amino acids at a given site and at least 2 of them occurring with a
minimum frequency of 2), S: singletons (at least 2 different amino acids at a given
site with at most 1 of them occurring multiple times).
(When you have a coding DNA sequence you can translate it into a protein
sequence by clicking on UUC->Phe. Clicking again you go back to the DNA
sequence).
-
Can you discover some groups by looking at the Pi characters?
-
Move sequences to have OsFT2 close to TaFT2, and also TaFT, OsFTa, and
OsFTb close to each other. Can you see patterns now?
D3. To see the format of a MEGA file, in the MEGA4 window, go to File|Export Data,
and click on OK to take a look at it. Exit (File|Exit Editor) this window.
D4.
Mutations T
V
L
Q
D
P
TaFT2
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Which of the 3 mutations found in a TILLING screen of TaFT2 would you prioritize for
characterizing a non-functional TaFT2 gene?
BLOSUM62 information for mutations: TQ= -1; VD=-3; LP=-3
BLOSUM62 information for changes at the mutation positions: TI= -1; VI=3; IL=2; EL=-2)
Maximize the conservation of the position and the negative impact of the mutation…
D5. Using T-COFFEE as a consistency based program
Copy the sequences below and open t-COFFEE in your web browser: http://tcoffee.vitalit.ch/cgi-bin/Tcoffee/tcoffee_cgi/index.cgi. Use the Regular form of T-COFFEE. Paste
the sequences in the INPUT window and press submit. Click on the link for score_pdf
and save the file. (NOTE: Once the file is saved you may need to rename it so that it is a
.pdf file, or it may not open properly.)
>OsVIL1
MASSAGGDPPPPGLFAAALHACSGASALEEHIHADDSNTISDNTLEQLGFLDQESNDASVNTEKIQSSTPKCKSVEDIPIAPAAKRCKN
MDSKKLVPNSNNNSCLTGSQAPRKLPRKGDYPVQLRRNETFQDTKPPSTWICKNAACKAVLTADNTFCKRCSCCICHLFDDNKDPSLWL
VCSSETGDRDCCESSCHIECALQHQKVGCVDLGQSIQLDGNYCCAACGKVIGILGFWKRQLMVAKDARRVDILCSRIYLSHRLLDGTTR
FKEFHKIVEDAKAKLETEVGPLDGTSSKMARGIVGRLPVAADVQKLCSLAIDMADAWLKSNCKAETKQIDTLPAACRFRFEDITTSSLV
VVLKEAASSQYHAIKGYKLWYWNSREQPSTRVPAIFPKDQRRILVSNLQPCTEYAFRIISFTEYGDLGHSECKCFTKSVEIIHKNMEHG
AEGCSSTAKRDSKSRNGWSSGFQVHQLGKVLRKAWAEENGCPSEACKDEIEDSCCQSDSALHDKDQAAHVVSHELDLNESSVPDLNAEV
VMPTESFRNENICSPGKNGLRKSNGSSDSDICAEGLVGEAPAMESRSQSRKQTSDLEQETYLEQETGADDSTLLISPPKHFSRRLGQLD
DNYEYCVKVIRWLECSGHIEKDFRMKFLTWFSLRSTEQERRVVITFIRTLADDPSSLAGQLLDSFEEIVSSKKPRTGFCSKLWH*
>TmVIL1
MESTGGDPSGFAAAALHASSDVSEHEEIKPADDSNTISDYAQEPLNFFPEQESNDASVSTEKKESVVSKCKSVEEIPREATVKRCKNID
SKKLFSNNKNSPSLTGIQALRKPPRKGPHPIQLRESEMFQDKKPPSTWICKNAACKAVLTSENTFCKRCSCCICHLFDDNKDPSLWLVC
SSETGDTDCCESSCHVECALQRRKAGRIDLGQSMHLDGNYCCAACGKVIGILGFWKRQLAVAKDARRVDILCSRIYLSHRLLDGTTRFK
ELHQIVQDAKAKLETEVGPLDGSSKMARCIVGRLPVAADVQKLCSLAMEKVDDWLQSNSQAETKQIDTLPTACRFRFEDITASSLVIVL
KETASSQYHAIKGYKLWYWNSREPPSTGEPVIFPKDQRRILISNLQPCTEYAFRIISFVEDGELGHSESKCFTRSVEIMHKNIEHGAEG
CSSTAKRNVKRHNGRSSGFKVRQLGKVLRRAWEEDGFPSEFCKDEIEDSCDQSDSVILEKGQVAHVVSRKLDLNETSVPDLNAEVVMPT
ECLRNENAYSSGKNDLRKSNGCGDFATCTEGHVGEAPAMESRSQSRKQTSDLEQETCAEDGNLVIGSQRHFSRRLGELDNNYEYCVKTI
RWLECCGHIEKEFRMRFLTWFSLRSTEQERRVVLTFIRTLVDEPGSLAGQLLDSFEEIVASKRPRTGFCTKLWH*
>OsVIL2
MDPPYAGVPIDPAKCRLMSVDEKRELVRELSKRPESAPDKLQSWSRREIVEILCADLGRERKYTGLSKQRMLEYLFRVVTGKSSGGGVV
EHVQEKEPTPEPNTANHQSPAKRQRKSDNPSRLPIVASSPTTEIPRPASNARFCHNLACRATLNPEDKFCRRCSCCICFKYDDNKDPSL
WLFCSSDQPLQKDSCVFSCHLECALKDGRTGIMQSGQCKKLDGGYYCTRCRKQNDLLGSWKKQLVIAKDARRLDVLCHRIFLSHKILVS
TEKYLVLHEIVDTAMKKLEAEVGPISGVANMGRGIVSRLAVGAEVQKLCARAIETMESLFCGSPSNLQFQRSRMIPSNFVKFEAITQTS
VTVVLDLGPILAQDVTCFNVWHRVAATGSFSSSPTGIILAPLKTLVVTQLVPATSYIFKVVAFSNYKEFGSWEAKMKTSCQKEVDLKGL
MPGGSGLDQNNGSPKANSGGQSDPSSEGVDSNNNTAVYADLNKSPESDFEYCENPEILDSDKASHHPNEPTNNSQSMPMVVARVTEVSG
LEEAPGLSASALDEEPNSAVQTQLLRESSNSMEQNQRSEVPGSQDASNAPAGNEVVIVPPRYSGSIPPTAPRYMENGKDISGRSLKAKP
GDNILQNGSSKPEREPGNSSNKRTSGKCEEIGHKDGCPEASYEYCVKVVRWLECEGYIETNFRVKFLTWYSLRATPHDRKIVSVYVNTL
IDDPVSLSGQLADTFSEAIYSKRPPSVRSGFCMELWH*
>TmVIL2
MDPPYAGAIIEPAKCRLMSVDEKKDLVRELSKRPQTAPDKLQSWSRRDIVEILCADLGRERKYTGLSKQRMLDYLFRVVTGKSSGPVVH
VQEKEPTLDPNTSNHQYPAKRQRKSDNPSRLPIAVNNPQTAVVPVQINNVRSCRNIACRAILSMEDKFCRRCSCCICFKYDDNKDPTIW
LSCSSDHPMQKDSCGLSCHLECALKDGRTGILPSGQCKKLDGAYYCPNCRKQHDLLRSWKKQLMLAKEARRLDILCYRIFLGHKVLFST
EKYSVLHKFVDIAKQKLEAEVGSVAGHGSMGRGIVSRLTCGAEVQKLCAEALDVMQSKFPVESPTNSQFERSNMMPSSFIKFEPITPTS
ITVVFDLARCPYISQGVTGFKVWHQVDGTGFYSLNPTGTVHLMSKTFVVTALKPATCYMIKVTAFSNSSEFVPWEARVSTSSLKESDLK
GLAPGGAGLVDQNNRSPKTNSGGQSDRSSEGVDSNNNATVYTDLNKSPESDFEYCENPEILDSDKVPHHPNGPSNNLQNMQIVAARVPE
VTELEEAPGLSASALDEEPNSTVQAALLRESSNSMEQNQRSEVPISQDASNATAGVELALVPRFVGSMPPTAPRVMETGKETGGRSFNT
KPSDNIFQNGSSKPDREPGNSSNKRSGKFEDAGHKDGCPEATYEYCVRVVRWLETEGYIETNFRVKFLTWYSLRATPHDRKIVSVYVDT
LINDPASLCGQLTDTFSEAIYSKKPPSVPSGFCMNLWH*
Note: NCBI multiple alignment tool for proteins is COBALT: it does progressive multiple
alignment of protein sequences. The alignment is aided by a collection of pairwise constraints
derived from conserved domain database, protein motif database, and local sequence similarity
using RPS-BLAST, BLASTP, and PHI-BLAST, respectively. Computation time is reduced by
forming clusters of sequences that share a large number of common words and finding
conserved domains and motif matches for only one sequence per cluster.
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D6. Creating a graphical representation of amino acid conservation.
A FASTA file of the first 50 amino acids of the FT protein alignment has been saved in
the 10_Lab3 folder. Open the FASTA file, ‘FTclipped.fas’, using Microsoft Word.
Copy the FASTA alignment and paste it in the Multiple Sequence Alignment window of
WebLogo: http://weblogo.berkeley.edu/logo.cgi. Click Create Logo.
E. Calculating a Distance Matrix
E1. In the MEGA4 window, go to Distances|Compute Pairwise. In the ‘Analysis
Preferences’ window, change ‘Model’ to Amino Acid|No. of differences (leave
the default parameters in the other options). Click on Compute.
E2. See the Pairwise Distances matrix.
-
Which sequences are the closest ones?
-
Which sequences are the most distant ones?
E3. To see the matrix in a MEGA file and save it, go
to File|Export/Print Distances, and change
the ‘Output Format’ from ‘Publication’ to
‘MEGA’. Click on Print/Save Matrix.
E4. After you have inspected the matrix, go to File|Quit Viewer to close the Pairwise
Distances matrix.
F. Drawing a Phylogenetic Tree
F1. In the MEGA4 window, go to Phylogeny|Construct Phylogeny|Neighbor-Joining
(NJ). In the ‘Analysis Preferences’ window, in the ‘Options Summary’ tab,
change ‘Model’ to Amino Acid|No. of differences. (leave the default parameters
in the other options). Click on Compute.
F2. See the tree in the Tree Explorer window.
F3. To select a branch, left-click on it. If you right-click on a branch, you will find
several options to perform different operations on the ‘Selected subtree’. To edit
the accession labels, double-click on them. Change the branch style by selecting
the View|Tree/Branch Style.
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F4. To save the tree to the clipboard and then be able to save it in a Word document, go
to Image|Copy to clipboard. Open a Word document and paste this tree. Exit the
Tree Explorer window (File|Exit Tree Explorer), without saving.
-
Use Phylogeny|Contruct Phylogeny to produce minimum evolution, maximum
parsimony and UPGMA trees. Copy and paste each of them into the same Word
document to compare them. Are the results consistent?
NJ
OsFTa
TaFT
OsFTb
OsFT2
TaFT2
AtFT
AtTSF
AtTFL1
UPGMA
OsFTa
10
TaFT
OsFTb
OsFT2
TaFT2
AtFT
AtTSF
AtTFL1
30
Max
Parsimony
20
10
0
AtFT
AtTSF
AtTFL1
TaFT
OsFTa
OsFTb
OsFT2
TaFT2
8
Min
Evolution
OsFTa
TaFT
OsFTb
OsFT2
TaFT2
AtFT
AtTSF
AtTFL1
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G. Evaluating a Phylogenetic Tree
G1. In the MEGA4 window, go to Phylogeny|Construct Phylogeny|Neighbor-Joining
(NJ). In the ‘Analysis Preferences’ window, in the ‘Test of Phylogeny’ tab, select
‘Bootstrap’ with 1,000 replications. Click on Compute.
G2. See the tree and the bootstrap values in the Tree Explorer window.
-
What is the confidence of the OsFTa-TaFT branch?
G3. Go to Image|Copy to clipboard and paste the tree into your Word document. Exit
the Tree Explorer window (File|Exit Tree Explorer), without saving.
H. Within MEGA Alignment Explorer we can retrieve sequences directly from
GenBank
We have discovered a MADS box protein from barley (GenBank # CAB97352) and we
want to determine the closest protein in among the following three Arabidopsis proteins:
AP1= CAA78909; AGL2= AAA32732; AGL6= AAA79328).
H1. In the MEGA4 window, go to Alignment|Query databanks.
H2. In the NCBI Entrez site, select Protein database, enter the first GenBank number
CAB97352 into the search box, and click on Go. When the search result is
displayed, open it and then click on ‘Add to Alignment’.
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H3. Repeat step G2. for the three Arabidopsis sequences.
H4. Align the protein sequence using ClustalW as before, save the alignment as
‘MADS.mas’, exit and open the file in MEGA.
H5. Perform a Neighbor-Joining (NJ) analysis. Copy and paste the phylogenetic tree
into your Word document.
-
Which Arabidopsis protein is the closest one to the MADS box protein from
barley?
I. Viewing the 3D structure of a protein
I1. Cn3D is an application that allows you to view 3-dimensional structures of proteins.
Go to protein blast (blastp).
Copy and paste AtFT protein sequence and click on BLAST.
I2. Once your results are completely displayed, go to Show Conserved Domains.
-
What is the name of the conserved domain?
Click on it to find more information about the conserved domain.
- What biological functions have been attributed to this
conserved domain?
H3. Click on Structure to go to Entrez, Structure database. In
the Structure database, insert the name of the conserved domain
you found and click on Go. Click on the link displayed as your
results. In the Structure Summary window, click on Structure
View in Cn3D. Open the file with Cn3D. Cn3D tutorial:
http://www.ncbi.nlm.nih.gov/Structure/CN3D/cn3dtut.shtml .
I4. Go to View|Animation|Spin for a complete view of the 3D structure of the conserved
domain. You can change the Style in which you want to see the 3D structure.
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The default display presented in the figure for single structures is a combination of
Style/Rendering Shortcuts: Worms and Style/Coloring Shortcuts: Secondary
Structure, which show a worm backbone, no side chains, and solid objects - arrows
and cylinders - to represent strands and helices. The colors are green for helices,
orange for strands, and blue for coils. Arrows point in the N-to-C direction.
I5. In the Sequence/Alignment Viewer, you can see where in the 3D structure the selected
amino acids are located, by simply selecting them with your mouse. The 3D structure
will be highlighted in the position where the selected amino acids are located.
Align a query protein to a similar sequence from a 3D structure and interactively view
sequence/structure relationships
Even if a 3D structure for your protein of interest has not yet been resolved, it is possible to
align your query protein to a similar sequence from a 3D structure.
1. Open the Entrez Protein (http://www.ncbi.nlm.nih.gov/protein) search page
2. Retrieve your sequence record of interest, for example wheat FT AAW23034
3. In the Links menu in the right select Related Structure (Summary) (at the bottom of
the right list). This will retrieve a list of protein sequences that are present in 3D structure
records and that were found by CBLAST (compares a query protein against all protein
sequences from resolved 3D structures).
4. To view a sequence alignment of the query and a hit of interest (2IQY_A), click on the
pink bar that represents the alignment.
5. On the sequence alignment display, press the View Structure and Alignment in Cn3D
button to save the file and then open with Cn3D
6. Once the Cn3D display is open, you can click on any amino acids from the retrieved
structure, in either the 3D structure or the sequence alignment window, to highlight their
location in both views and examine the sequence/structure relationship. The Cn3D
Tutorial provides more information about using the program, and the third comment
under additional notes, below, provides step-by-step instructions on how to generate the
specific view shown in the illustration on this page.
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J. From Multiple Sequence Alignment to Multiple Sequence Assembly
J.1. Using MEGA4, perform a new ClustalW alignment with the 8 exported sequences
used in 10_Lab1 (simply select them all from the Word document called
‘10_Lab1 DNA for MEGA’, copy them (Ctrl C) and paste them (Ctrl V) in the
MEGA4 Alignment Explorer window).
-
Could you get a good alignment of the sequences? Why?
-
How would you find the alignment between the overlapping regions that are
present in these sequences?
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