From Transcriptome to Secretome: Bioinformatics Protocol and Tool Development for EST Sequence Analysis, Annotation and Identification of Secretory Proteins. Dr. Jack Min. Extra-Readings. EST_review.pdf EST_piper.pdf OrfPredictor.pdf TargetIdentifier.pdf. Project Objectives.
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Project Objectives Identifying secretory enzymes from 15 fungal species by high throughput EST sequencing. Evaluation of the potential applications of identified enzymes in industrial processing and in environmental remediation.
EST ? EST: Expressed Sequence Tag. Single-pass (single-run) sequencing for a cDNA clone, usually from one end. The sequences generated in our fungal genomics project are ESTs.
Bioinformatics Objectives To control EST sequence quality: remove vector contaminants and low quality portions. To assemble ESTs into contigs/singletons to improve the sequence accuracy and predict the unique gene number. To functionally annotate ESTs and their assemblies: functionality, predicted protein sequences, functional domains, signal peptide.
Bioinformatics Objectives To identify potential target full-length ESTs and their assembled contigs. Targets: secretory enzymes. To map ESTs to the genome – to elucidate its gene structure. To make the data accessible to biologists.
Bioinformatics Subsystems & Databases GO Annotation (AmiGO) CloneTrack Internal EST Annotation Public EST Annotation Genome Annotation (EST to Genome & Gene Prediction) MicroArray (BASE) TargetFinding Secretome Analysis Re-sequenced Clone Annotation Passport
Sequence Quality Control and Assembling Pipeline 1 Sequence Chromatograms Phred Lucy BLASTN (E. coli/vector/plasmid DB) bvpFinder(remove contaminants) Phrap Singletons/contigs
Bioinformatics Protocols and Tools Pipeline 1: sequence quality control and assembling (Figure 1) Sequence chromatograms: a file generated by a sequencing machine. Phred: a base calling program to get a base and its score. Lucy: a program to trim low quality sequences and remove vector contaminants. Phrap: an assembler to assemble overlapped ESTs to generate a consensus sequence.
Sequence Data Analysis • Phred (Dr. Green):reads DNA sequencer trace data, calls bases, assigns quality values, and writes the base calls and quality values to output files. • q = -10*log10(p) q: quality value, p: estimated error probability for a base call.
Sequence Data Analysis • Lucy (Dr. Chou):a utility that prepares raw DNA sequence fragments for sequence assembly. • computes good quality regions; • removes vector contaminants; • chops off splice sites (vector and adaptor) from the sequence; • removes shorter insert sequences; • produces the cleaned sequence file for good quality regions, and a companion quality file
Sequence Data Analysis • bvpFinder: our in-house program to identify contaminants. • Phrap (Dr. Green): a program for assembling DNA sequences. • Input: sequence file and quality file from Lucy. • Output: sigletons, contigs, and ace file.
Data obtained after running Pipeline1 • Total sequence number; • Low quality sequence number; • Short sequence number; • Vector and other contaminant number; • Good sequence number; • Average good sequence length; • Singleton number; • Contig number.
Sequence Annotation Pipeline 2 BLASTX Sequence file (ESTs/Assemblies) TargetIdentifier/Annotator hit No hit Function known Function unknown OrfPredictor CDD, SignalP, TMHMM, Phobius, GO
Pipeline 2 sequence annotation BLASTX: NCBI-BLAST DNA against NCBI non-redundant protein database. TargetIdentifier/Annotator: an in-house tool for predicting whether a query cDNA sequence is full length or not; functional annotation based on BLASTX. Available as web server for public. OrfPredictor: an in-house program to predict the open reading frame of an anonymous cDNA sequence. Available as web server for public. SignalP: a program to predict if a protein contains a signal peptide. TMHMM: transmembrane domain prediction. Phobius: signal peptide and transmembrane domain predicton. GO: gene ontology mapping.
An Example of BLASTX Output Query= Asn_00765_MB111_076.ab1 CHROMAT_FILE: Asn_00765_MB111_076.ab1 PHD_FILE: Asn_00765_MB111_076.ab1.phd.1 CHEM: Unknown DYE: Unknown ET TIME: Mon Sep 23 16:14:14 2002 (483 letters) Database: FungalTargetDB 28,671 sequences; 10,818,323 total letters Searching..................................................done Score E Sequences producing significant alignments: (bits) Value gi|17544913|ref|NP_518315.1| PROBABLE ZINC_DEPENDENT ALCOHOL DEH... 38 1E-20 >gi|17544913|ref|NP_518315.1| PROBABLE ZINC_DEPENDENT ALCOHOL DEHYDROGENASE OXIDOREDUCTASE PROTEIN [Ralstonia solanacearum] Length = 345 Score = 38.1 bits (87), Expect = 1E-20 Identities = 17/39 (43%), Positives = 25/39 (63%) Frame = +1 Query: 367MRAVDFRGPYKVADEERPVPRIQDAGDIVVSVTYTALWG 483 M+A+ + GP K++ E +P P +Q GD VV VT T + G Sbjct: 1MKALVYEGPGKISLENKPKPELQAPGDAVVRVTLTTICG 39 Jack Min, Concordia University, Montreal, QC
▲ 5’ ☺ 3’ ▲? 5’ 5’ 5’ ☺ 3’ 3’ 3’ d1 X ☺ Hit (Subject) d2 X If (d2-d1) < 10, Full-length, then check 3’-stop codon; Else If 10<=(d2-d1) <50, Short (#) Full-length, then check 3’-stop codon; Else Partial. 5’ ☺ 3’ Ambiguous Partial Algorithm for Identifying Full-length Genes *stop codon before start codon ☺start codon ▲stop codon after start codon * Full-length, Completely sequenced * Full-length, not completely sequenced | * Jack Min, Concordia University, Montreal, QC
In In - - frame start frame start codon codon no no yes yes 5 5 ’ ’ stop stop condon condon 5 5 ’ ’ stop stop condon condon yes yes no no yes yes no no (d1 + d3/3 (d1 + d3/3 Full Full - - length length Ambiguous Ambiguous (d2 (d2 – – d1) d1) – – – – d2) d2) ? ? 0 0 < 10 < 10 yes yes no no yes yes no no Full Full - - length length (d2 (d2 (d2 (d2 – – – – d1) d1) d1) d1) Possible full Possible full - - Partial Partial < 50 < 50 < 50 length length yes yes no no Short full Short full - - (d1 + d3/3 (d1 + d3/3 length length – – – – d2) d2) ? 0 0 yes yes no no Possible full Possible full - - Partial Partial length length
Bioinformatics Protocols and Tools Pipeline 3 mapping to genome SIM4: A program to map cDNAs to genomic DNA sequences. SIM2GFF: our in-house tool used to convert SIM4 output into GFF format and to integrate functional annotation. Generic Genome Browser: a web browser for displaying genome annotation.