Task 2: Sequence alignments (sequence searches and multiple alignments)
- 1 Task description
- 2 Task 2.1: Sequence searches
- 3 Task 2.2: Multiple sequence alignments
The full description of this task can be found here.
Task 2.1: Sequence searches
time sudo blastall -p blastp -d '/data/blast/nr/nr' -i ./reference.fasta -o './reference.blast' -b 500
Found true positives 220 of 500 predictions.
- Used Virtual Box with Linux.
- Download fasta3.tar.gz from ftp://ftp.ebi.ac.uk/pub/software/unix/fasta/
- Unzip the archive
- Build it with: make -f /apps/fasta/make/Makefile.linux64 all
time ./fasta36 /home/student/reference.fasta /data/nr/nr
- Enter filename for results : /home/student/reference.fasta_search
- How many scores do you want to see: 500
- More scores? 0
- Display alignments also? (y/n) [n] y
- number of alignments ? 500
Found positives 224 of 500 predictions.
time blastpgp -d '/data/nr/nr' -i './reference.fasta' -o './reference_psi_e10E-6_i3.blast' -h 10E-6 -j 3 -C './reference_i3_e10E-6.chk'
time blastpgp -d '/data/nr/nr' -i './reference.fasta' -o './reference_psi_e005_i3.blast' -h 0.005 -j 3 -C './reference_i3_e005.chk'
time blastpgp -d '/data/nr/nr' -i './reference.fasta' -o './reference_psi_e005_i5.blast' -h 0.005 -j 5 -C './reference_i5_e005.chk'
time blastpgp -d '/data/nr/nr' -i './reference.fasta' -o './reference_psi_e10E-6_i5.blast' -h 10E-6 -j 5 -C './reference_i5_e10E-6.chk'
3 Iterations, 10E-6 E-Value-Threshold In iteration 2 220/500 In iteration 3 224/500 Psi-Blast had during the different iterations 255 different positives at least one time in its result list.
3 Iterations, 0.005 E-Value-Threshold In iteration 2 220/500 In iteration 3 225/500 Psi-Blast had during the different iterations 256 different positives at least one time in its result list.
5 Iterations, 0.005 E-Value-Threshold In iteration 2 220/500 In iteration 3 225/500 In iteration 4 223/500 In iteration 5 225/500 Psi-Blast had during the different iterations 261 different positives at least one time in its result list.
5 Iterations, 10E-6 E-Value-Threshold In iteration 2 220/500 In iteration 3 224/500 In iteration 4 223/500 In iteration 5 226/500 Psi-Blast had during the different iterations 260 different positives at least one time in its result list.
Preparing the HHM-Database
- Download pdb70_29May10.hhm.tar.gz from ftp://ftp.tuebingen.mpg.de/pub/protevo/HHsearch/databases/
- Unzip the archive
- Make a database: cat *.hhm >> pdb70.db
- Move the db to an appropriate directory: sudo mv pdb70.db ../pdb70.db
In the manual of HHSearch it was adviced to add the information of the secondary structure to the multiple alignment used for the query. Therefore it was necessary to run the addpsipred script of HHSearch. This script was not configured in the virtual box. Several parameters have to be adjusted.
- Changes in /apps/bin/addpsipred:
- Copy /apps/bin/reformat to /apps/bin/reformat.pl
time hhsearch -i ./reference.fasta -d /data/hmm/pdb70.db -b 500 -o ./reference_simple.hhsearch
alignblast reference_psi_e10E-6_i3.blast reference_psi_e10E-6_i3.a3m
time hhsearch -i reference_psi_e10E-6_i3.a3m -d /data/hmm/pdb70.db -o reference_psi_e10E-6_i3.hhsearch
To run HHSearch with the profile of a PSI-BLAST search the output of PSI-BLAST has to be converted to a multiple alignment by the script alignblast. The performance of HHSearch can be increases by adding the information of the secondary structure to the multiple alignment. This can be done with the script addspipred (uses the secondary structure prediction of PSIPRED).
alignblast reference_psi_e005_i3.blast reference_psi_e005_i3.a3m
time hhsearch -i reference_psi_e005_i3.a3m -d /data/hmm/pdb70.db -o reference_psi_e005_i3.hhsearch
alignblast reference_psi_e005_i5.blast reference_psi_e005_i5.blast.a3m
time hhsearch -i reference_psi_e005_i5.blast.a3m -d /data/hmm/pdb70.db -o reference_psi_e005_i5.blast.hhsearch
alignblast reference_psi_e10E-6_i5.blast reference_psi_e10E-6_i5.a3m
time hhsearch -i reference_psi_e10E-6_i5.a3m -d /data/hmm/pdb70.db -o reference_psi_e10E-6_i5.hhsearch
Comparing the Results
HSSP - Some Positives
Getting the entry of PAH from HSSP http://mrs.cmbi.ru.nl/mrs-5/entry?db=hssp&id=2pah&q=phenylalanine%20hydroxylase
HSSP - More Positives
HHSearch was run with a dataset of the PDB. BLAST was run with the a dataset of the NR database. NR itself is a mixture of SwissProt, RefSeq, PIR, PRF, PDB and GenBank CDS translations. HSSP itself contains only references to SwissProt entries. Therefore it was necessary to get the cross-references of the Swissprot entries in HSSP to the other databases. For this purpose we created a java-tool (only runable with linux).
Task 2.2: Multiple sequence alignments
For each identity range (99%-90%, 89%-60, 59%-40% and 39%-20%) we selected five sequences of which at least one sequence has a solved structure as well. In order to find these sequences we looked in our blast and psi-blast results for appropriate sequences, four for each identity range. A sequences was considered as appropriate if it has the wanted sequence identity to our reference sequence and if this sequence has roughly the same length as our reference sequence. The reason for this is that we wanted to avoid leading and trailing gaps in our alignments. However, this was not always possible , especially for the low identity range (39%-20%). Last but not least, we used our hhsearch results (which was queried against a profile database of all pdb entries) to find appropriate sequences for each identity range. The list of selected sequences is as follows:
|95%||1J8T||catalytic domain of human phenylalanine hydroxylase Fe(II)|
|94%||296212713||PREDICTED:phenylalanine-4-hydroxylase [Callithrix jacchus]|
|89%||126339754||PREDICTED: similar toPhenylalanine-4-hydroxylase (PAH) (Phe-4-monooxygenase)[Monodelphis domestica]|
|82%||224095451||PREDICTED: phenylalanine hydroxylase [Taeniopygia guttata]|
|73%||32442452||Pah [Danio rerio]|
|66%||3HF6||crystal structure of human tryptophan hydroxylase type 1 with bound LP-521834 and FE|
|60%||194865387||GG14450 [Drosophila erecta]|
|59%||2TOH||TYROSINE HYDROXYLASE CATALYTIC AND TETRAMERIZATION DOMAINS FROM RAT|
|56%||4883767||PREDICTED: phenylalanine hydroxylase [Caenorhabditis elegans]|
|48%||74096365||tyrosine hydroxylase 2 [Takifugu rubripes]|
|48%||301617387||PREDICTED: tyrosine3-monooxygenase-like [Xenopus (Silurana) tropicalis]|
|45%||115532103||TryPtophan Hydroxylase familymember (tph-1) [Caenorhabditis elegans]|
|37%||85860954||prephenate dehydratase [Syntrophus aciditrophicus SB]|
|31%||114570403||phenylalanine 4-monooxygenase [Maricaulis maris MCS10]|
|30%||1LTV||CRYSTAL STRUCTURE OF CHROMOBACTERIUM VIOLACEUM PHENYLALANINE HYDROXYLASE, STRUCTURE WITH BOUND OXIDIZED Fe(III)|
|25%||94312464||phenylalanine 4-monooxygenase[Cupriavidus metallidurans CH34]|
|23%||298578904||aromatic amino acid hydroxylase[Chlamydophila pneumoniae]|
Then we created a FASTA file for each identity range which contains the 5 sequences selected and our PAH reference sequence. For this purpose we executed the following commands:
cat reference_pah_aa.fasta gi_4557819.fasta pdb_1J8T.fasta gi_296212713.fasta gi_301759315.fasta gi_171543886.fasta > ../99_90.fasta
cat reference_pah_aa.fasta gi_126339754.fasta gi_224095451.fasta gi_32442452.fasta pdb_3hf6.fasta gi_194865387.fasta > ../89_60.fasta
cat reference_pah_aa.fasta pdb_2TOH.fasta gi_4883767.fasta gi_74096365.fasta gi_301617387.fasta gi_115532103.fasta > ../59_40.fasta
cat reference_pah_aa.fasta gi_85860954.fasta gi_114570403.fasta pdb_1ltv_fasta gi_94312464.fasta gi_298578904.fasta > ../39_20.fasta
Creating multiple sequence alignments with Cobalt
Before we could start to create our multiple sequence alignments (MSA) with Cobalt we had to install it first. We retrieved the latest copy from the NCBI server and installed it with the following commands:
//download of cobalt
//set enviroment var
//make cobalt.linux executable
chmod +x cobalt.linux