HWbash

Lecture on Perl, Lecture on command-line tools

• In this set of tasks, use command-line tools or one-liners in Perl, awk or sed. Do not write any scripts or programs.
• Each task can be split into several stages and intermediate files written to disk, but you can also use pipelines to reduce the number of temporary files.
• Your commands should work also for other input files with the same format (do not try to generalize them too much, but also do not use very specific properties of a particular input, such as the number of lines etc.)
• Include all relevant used commands in your protocol and add a short description of your approach.
• Submit the protocol and required output files.
• Outline of the protocol is in /tasks/bash/protocol.txt, submit to directory /submit/bash/yourname

Task A (yeast genome)

The input file:

• /tasks/bash/saccharomyces_cerevisiae.gff contains annotation of the yeast genome
  • Downloaded from http://yeastgenome.org/ on 2016-03-09, in particular from [1].
  • It was further processed to omit DNA sequences from the end of file.
  • The size of the file is 5.6M.
• For easier work, link the file to your directory by ln -s /tasks/bash/saccharomyces_cerevisiae.gff yeast.gff
• The file is in GFF3 format
• The lines starting with # are comments, other lines contain tab-separated data about one interval of some chromosome in the yeast genome
• Meaning of the first 5 columns:
  • column 0 chromosome name
  • column 1 source (can be ignored)
  • column 2 type of interval
  • column 3 start of interval (1-based coordinates)
  • column 4 end of interval (1-based coordinates)
• You can assume that these first 5 columns do not contain whitespace

Task:

• Print for each type of interval (column 2), how many times it occurs in the file.
• Sort from the most common to the least common interval types.
• Hint: commands sort and uniq will be useful. Do not forget to skip comments, for example using grep -v '^#'
• The result should be a file types.txt formatted as follows:

   7058 CDS
   6600 mRNA
...
...
      1 telomerase_RNA_gene
      1 mating_type_region
      1 intein_encoding_region

Submit the file types.txt

Task B (chromosomes)

• Continue processing file from task A.
• For each chromosome, the file contains a line which has in column 2 string chromosome, and the interval is the whole chromosome.
• To file chrosomes.txt, print a tab-separated list of chromosome names and sizes in the same order as in the input
• The last line of chromosomes.txt should list the total size of all chromosomes combined.
• Submit file chromosomes.txt
• Hints:
  • The total size can be computed by a perl one-liner.
  • Example from the lecture: compute the sum of interval sizes if each line of the file contains start and end of one interval: perl -lane'$sum += $F[1]-$F[0]; END { print $sum; }'
  • Grepping for word chromosome does not check if this word is indeed in the second column
  • Tab character is written in Perl as "\t".
• Your output should start and end as follows:

chrI    230218
chrII   813184
...
...
chrXVI  948066
chrmt   85779
total   12157105

Task C (passwords)

• The file /tasks/bash/names.txt contains data about several people, one per line.
• Each line consists of given name(s), surname and email separated by spaces.
• Each person can have multiple given names (at least 1), but exactly one surname and one email. Email is always of the form username@uniba.sk.
• The task is to generate file passwords.csv which contains a randomly generated password for each of these users
  • The output file has columns separated by commas ','
  • The first column contains username extracted from email address, the second column surname, the third column all given names and the fourth column the randomly generated password
• Submit file passwords.csv with the result of your commands.

Example line from input:

Pavol Orszagh Hviezdoslav hviezdoslav32@uniba.sk

Example line from output (password will differ):

hviezdoslav32,Hviezdoslav,Pavol Orszagh,3T3Pu3un

Hints:

• Passwords can be generated using pwgen (e.g. pwgen -N 10 -1 prints 10 passwords, one per line)
• We also recommend using perl, wc, paste (check option -d in paste)
• In Perl, function pop may be useful for manipulating @F and function join for connecting strings with a separator.

Task D (blast)

Overall goal:

• Proteins from several well-studied yeast species were downloaded from database http://www.uniprot.org/ on 2016-03-09. The file contains sequence of the protein as well as a short description of its biological function.
• We have also downloaded proteins from the yeast Yarrowia lipolytica. We will pretend that nothing is known about the function of these proteins (as if they were produced by gene finding program in a newly sequenced genome).
• For each Y.lipolytica protein, we have found similar proteins from other yeasts
• Now we want to extract for each protein in Y.lipolytica its closest match among all known proteins and see what is its function. This will give a clue about the potential function of the Y.lipolytica protein.

Files:

• /tasks/bash/known.fa is a FASTA file containing sequences of known proteins from several species
• /tasks/bash/yarLip.fa is a FASTA file with proteins from Y.lipolytica
• /tasks/bash/known.blast is the result of finding similar proteins in yarLip.fa versus known.fa by these commands (already done by us):

formatdb -i known.fa
blastall -p blastp -d known.fa -i yarLip.fa -m 9 -e 1e-5 > known.blast

• you can link these files to your directory as follows:

ln -s /tasks/bash/known.fa .
ln -s /tasks/bash/yarLip.fa .
ln -s /tasks/bash/known.blast .

Step 1:

• Get the first (strongest) match for each query from known.blast.
• This can be done by printing the lines that are not comments but follow a comment line starting with #.
• In a Perl one-liner, you can create a state variable which will remember if the previous line was a comment and based on that you decide if you print the current line.
• Instead of using Perl, you can play with grep. Option -A 1 prints the matching lines as well as one line after each match
• Print only the first two columns separated by tab (name of query, name of target), sort the file by the second column.
• Store the result in file best.tsv. The file should start as follows:

Q6CBS2  sp|B5BP46|YP52_SCHPO
Q6C8R4  sp|B5BP48|YP54_SCHPO
Q6CG80  sp|B5BP48|YP54_SCHPO
Q6CH56  sp|B5BP48|YP54_SCHPO

• Submit file best.tsv with the result

Step 2:

• Create file known.tsv which contains sequence names extracted from known.fa with leading > removed
• This file should be sorted alphabetically.
• The file should start as follows (lines are trimmed below):

sp|A0A023PXA5|YA19A_YEAST Putative uncharacterized protein YAL019W-A OS=Saccharomyces...
sp|A0A023PXB0|YA019_YEAST Putative uncharacterized protein YAR019W-A OS=Saccharomyces...

• Submit file known.tsv

Step 3:

• Use command join to join the files best.tsv and known.tsv so that each line of best.tsv is extended with the text describing the corresponding target in known.tsv
• Use option -1 2 to use the second column of best.tsv as a key for joining
• The output of join may look as follows:

sp|B5BP46|YP52_SCHPO Q6CBS2 Putative glutathione S-transferase C1183.02 OS=Schizosaccharomyces...
sp|B5BP48|YP54_SCHPO Q6C8R4 Putative alpha-ketoglutarate-dependent sulfonate dioxygenase OS=...

• Further reformat the output so that the query name goes first (e.g. Q6CBS2), followed by target name (e.g. sp|B5BP46|YP52_SCHPO), followed by the rest of the text, but remove all text after OS=
• Sort by query name, store as best.txt
• The output should start as follows:

B5FVA8  tr|Q5A7D5|Q5A7D5_CANAL  Lysophospholipase
B5FVB0  sp|O74810|UBC1_SCHPO    Ubiquitin-conjugating enzyme E2 1
B5FVB1  sp|O13877|RPAB5_SCHPO   DNA-directed RNA polymerases I, II, and III subunit RPABC5

• Submit file best.txt

Note:

• Not all Y.lipolytica proteins are necessarily included in your final output (some proteins do not have blast match).
  • You can think how to find the list of such proteins, but this is not part of the task.
• Files best.txt and best.tsv should have the same number of lines.