• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.2
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• pp.101-107
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• 2002

We describe here the cDNA sequence and mRNA expression of a novel family of the antioxidant protein, peroxiredoxin, from the firefly, Pyracoetia ruin. The 555 bp cDNA sequence codes for a 185 amino acid protein with a calculated molecular mass of approximately 21 kDa. The deduced protein of P. rufa peroxiredoxin gene contains two conserved cysteine residues. Alignment of the deduced protein of P. rufa peroxiredoxin gene showed 71.1% protein sequenceidentity to known insect Drosophila melanogaster peroxiredoxin. Northern blot analysis revealed that the P. rufa peroxiredoxin is specifically expressed in the fat body of P. rufa larvae.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2000.11a
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• pp.28-31
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• 2000

We describe a hidden Markov model, HMMTIR, for general protein sequence based on the I-sites library of sequence-structure motifs. Unlike the linear HMMs used to model individual protein families, HMMSTR has a highly branched topology and captures recurrent local features of protein sequences and structures that transcend protein family boundaries. The model extends the I-sites library by describing the adjacencies of different sequence-structure motifs as observed in the database, and achieves a great reduction in parameters by representing overlapping motifs in a much more compact form. The HMM attributes a considerably higher probability to coding sequence than does an equivalent dipeptide model, predicts secondary structure with an accuracy of 74.6% and backbone torsion angles better than any previously reported method, and predicts the structural context of beta strands and turns with an accuracy that should be useful for tertiary structure prediction. HMMSTR has been incorporated into a public, fully-automated protein structure prediction server.

• Genomics & Informatics
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• v.4 no.4
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• pp.173-181
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• 2006

Pattern finding is one of the important tasks in a protein or DNA sequence analysis. Alignment is the widely used technique for finding patterns in sequence analysis. BLAST (Basic Local Alignment Search Tool) is one of the most popularly used tools in bio-informatics to explore available DNA or protein sequence databases. BLAST may generate a huge output for a large sequence data that contains various sequence patterns. However, BLAST does not provide a tool to summarize and analyze the patterns or matched alignments in the BLAST output file. BLAST lacks of general and robust parsing tools to extract the essential information out from its output. This paper presents a pattern summary system which is a powerful and comprehensive tool for discovering pattern structures in huge amount of sequence data in the BLAST. The pattern summary system can identify clusters of patterns, extract the cluster pattern sequences from the subject database of BLAST, and display the clusters graphically to show the distribution of clusters in the subject database.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.337-345
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• 2014

Pichia pastoris is one of the most widely used expression systems for the secretory expression of recombinant proteins. The secretory expression in P. pastoris usually makes use of the prepro $MAT{\alpha}$ sequence from Saccharomyces cerevisiae, which has a dibasic amino acid cleavage site at the end of the signal sequence. This is efficiently processed by Kex2 protease, resulting in the secretion of high levels of proteins to the medium. However, the proteins that are having the internal accessible dibasic amino acids such as KR and RR in the coding region cannot be expressed using this signal sequence, as the protein will be fragmented. We have identified a new signal sequence of 18 amino acids from a P. pastoris protein that can secrete proteins to the medium efficiently. The PMT1-gene-inactivated P. pastoris strain secretes a ~30 kDa protein into the extracellular medium. We have identified this protein by determining its N-terminal amino acid sequence. The protein secreted has four DDDK concatameric internal repeats. This protein was not secreted in the wild-type P. pastoris under normal culture conditions. We show that the 18-amino-acid signal peptide at the N-terminal of this protein is useful for secretion of heterologous proteins in Pichia.

• The Plant Pathology Journal
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• v.16 no.1
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• pp.36-42
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• 2000

The coat protein gene of iris severe mosaic potyvirus, which was isolated in Korea, ISMV-K, from iris plant was cloned and its nucleotide sequence was determined. The coat protein of the virus contained 252 amino acid residues, including five potential N-glyxosylation site motifs. The coat protein of ISMV-K has 99.1% and 98.4% sequence identities with those of the Netherlands isolate of ISMV (ISMV-Ne) form crocus for the nucleotide and amino acids, respectively. The coat protein of ISMV-K has 50.4% to 60.3% nucleotide sequence identities and 47.3% to 55.7% amino acid identities with those of other 21 potyviruses, indicating ISMV to be a distinct species of the genus. The coat protein of ISMV-K was closely related with bean yellow mosaic virus and clover yellow vein virus in the phylogenetic tree analysis among the potyviruses analyzed. ISMV was easily and reliably detected from virus-infected iris leaves by RT-PCR with a set of the virus-specific primers.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.1018-1020
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• 2003

The complete 1,486 nucleotide sequence of a cryptic plasmid separated from Lactobacillus bifermentans strain A02 isolated from Kimchi has been determined. The plasmid, designated as pA021, encodes a 33,488 Da putative Rep protein. Based on the sequence similarity, the protein shows homology with coding protein of pRS1, a previously reported plasmid of Oenococcus oeni and the replication initiation protein (Rep) of the Staphylococcal pT181 plasmid family.

• The KIPS Transactions:PartD
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• v.10D no.2
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• pp.261-266
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• 2003

A protein, which is a linear polymer of amino acids, is one of the most important bio-molecules composing biological structures and regulating bio-chemical reactions. Since the characteristics and functions of proteins are determined by their amino acid sequences in principle, protein sequence determination is the starting point of protein function study. This paper proposes a protein sequence prediction method based on data mining techniques, which can overcome the limitation of previous bio-chemical sequencing methods. After applying multiple proteases to acquire overlapped protein fragments, we can identify candidate fragment sequences by comparing fragment mass values with peptide databases. We propose a method to construct multi-partite graph and search maximal paths to determine the protein sequence by assembling proper candidate sequences. In addition, experimental results based on the SWISS-PROT database showing the validity of the proposed method is presented.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2001.06a
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• pp.77-80
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• 2001

A variety of different methods to generate diverse proteins, including random mutagenesis and recombination, are currently available, and most of them accumulate the mutations on the target gene of a protein, whose sequence space remains unchanged. On the other hand, a pool of diverse genes, which is generated by random insertions, deletions, and exchange of the homologous domains with different lengths in the target gene, would present the protein lineages resulting in new fitness landscapes. Here we report a method to generate a pool of protein variants with different sequence spaces by employing green fluorescent protein (GFP) as a model protein. This process, designated functional salvage screen (FSS), comprises the following procedures： a defective GFP template expressing no fluorescence is firstly constructed by genetically disrupting a predetermined region(s) of the protein, and a library of GFP variants is generated from the defective template by incorporating the randomly fragmented genomic DNA from E. coli into the defined region(s) of the target gene, followed by screening of the functionally salvaged, fluorescence-emitting GFPs. Two approaches, sequence-directed and PCR-coupled methods, were attempted to generate the library of GFP variants with new sequences derived from the genomic segments of E. coli. The functionally salvaged GFPs were selected and analyzed in terms of the sequence space and functional property. The results demonstrate that the functional salvage process not only can be a simple and effective method to create protein lineages with new sequence spaces, but also can be useful in elucidating the involvement of a specific region(s) or domain(s) in the structure and function of protein.

• BMB Reports
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• v.39 no.6
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• pp.717-721
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• 2006

In vitro analyses of type I signal peptidase activities require protein precursors as substrates. Usually, these pre-proteins are expressed in vitro and cleavage of the signal sequence is followed by SDS polyacrylamide gel electrophoresis coupled with autoradiography. Radioactive amino acids have to be incorporated in the expressed protein, since the amount of the in vitro expressed protein is usually very low and processing of the signal peptide cannot be followed by SDS polyacrylamide gel electrophoresis alone. Here we describe a rapid and simple method to express large amounts of a protein precursor in E. coli. We have analyzed the effect of ionophors as well as of azide on the accumulation of expressed protein precursors. Azide blocks the function of SecA and the ionophors dissipate the electrochemical gradient across the cytoplasmic membrane of E. coli. Addition of azide ions resulted in the formation of inclusion bodies, highly enriched with pre-apo-plastocyanine. Plastocyanine is a soluble copper protein, which can be found in the periplasmic space of cyanobacteria as well as in the thylakoid lumen of cyanobacteria and chloroplasts, and the pre-protein contains a cleavable signal sequence at its N-terminus. After purification of cyanobacterial pre-apo-plastocyanine, its signal sequence can be cleaved off by the E. coli signal peptidase, and protein processing was followed on Coomassie stained SDS polyacrylamide gels. We are optimistic that the presented method can be further developed and applied.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.87-90
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• 1995

Complementary DNA of the movement protein (MP) gene of tobacco mosaic virus Korean pepper strain (TMV-KP) was synthesized from purified TMV-KP RNA by using the reverse transcription and polymerase chain reaction (PCR) system. The synthesized double stranded cDNA was cloned into the plasmid pUC9 and transformed into Escherichia coli JM110. The movement protein gene of TMV-KP of the selected clones was subjected to sequence analysis by Sanger's dideoxy chain termination method. The complete sequence of viral MP gene from TMV-KP strain was 807 nucleotides long. The nucleotide of MP gene from TMV-KP has thirteen and two nucleotide differences from TMV vulgarae (TMV-OM) and Korean (TMV-K) strains, respectively. Thus, the nucleotide sequence of TMV-KP MP gene showed higher homology of 99% with that of TMV-K MP gene.