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PubMed1996

Methods for comparing a DNA sequence with a protein sequence.

We describe two methods for constructing an optimal global alignment of, and an optimal local alignment between, a DNA sequence and a protein sequence. The alignment model of the methods addresses the problems of frameshifts and introns in the DNA sequence. The methods require computer memory proportional to the sequence lengths, so they can rigorously process very huge sequences. The simplified versions of the methods were implemented as computer programs named NAP and LAP. The experimental results demonstrate that the programs are sensitive and powerful tools for finding genes by DNA-protein sequence homology.

Algorithms↗
PubMed2002

[Nucleotide sequence and protein sequence analysis of GL-7-ACA acylase from Pseudomonas sp. 130].

The nucleotide sequence and N-, C-terminal amino acid sequences of alpha,beta-subunit of glutaryl 7-ACA acylase C130 from Pseudomonas sp. 130 were determined. The alignment of the acylase C130 with the other acylases shows that it has high homology with the acylases from Pseudomonas sp. GK16 and C427, but low homology with the others. There is large difference in the N-terminal of alpha-subunit, while the N-terminal of beta-subunit has significant conservation.

Amino Acid Sequence↗
PubMed1989

EMBOPRO--an automatically generated protein sequence database.

For the identification of newly sequenced proteins it is necessary to have a large stock of known proteins for comparison. In this paper we present an automatically generated protein sequence database. The translation program introduced allows a periodical translation of every new release of the EMBL database. Possible errors of the translation are discussed as well as the reliability of the nucleotide sequence data, which turns out to be quite good. A comparison of our translated database with some established ones is given.

Amino Acid Sequence↗
PubMed2005

Pattern similarity study of functional sites in protein sequences: lysozymes and cystatins.

BACKGROUND: Although it is generally agreed that topography is more conserved than sequences, proteins sharing the same fold can have different functions, while there are protein families with low sequence similarity. An alternative method for profile analysis of characteristic conserved positions of the motifs within the 3D structures may be needed for functional annotation of protein sequences. Using the approach of quantitative structure-activity relationships (QSAR), we have proposed a new algorithm for postulating functional mechanisms on the basis of pattern similarity and average of property values of side-chains in segments within sequences. This approach was used to search for functional sites of proteins belonging to the lysozyme and cystatin families. RESULTS: Hydrophobicity and beta-turn propensity of reference segments with 3-7 residues were used for the homology similarity search (HSS) for active sites. Hydrogen bonding was used as the side-chain property for searching the binding sites of lysozymes. The profiles of similarity constants and average values of these parameters as functions of their positions in the sequences could identify both active and substrate binding sites of the lysozyme of Streptomyces coelicolor, which has been reported as a new fold enzyme (Cellosyl). The same approach was successfully applied to cystatins, especially for postulating the mechanisms of amyloidosis of human cystatin C as well as human lysozyme. CONCLUSION: Pattern similarity and average index values of structure-related properties of side chains in short segments of three residues or longer were, for the first time, successfully applied for predicting functional sites in sequences. This new approach may be applicable to studying functional sites in un-annotated proteins, for which complete 3D structures are not yet available.

Amino Acid Sequence↗
PubMed2002

Towards automatic clustering of protein sequences.

Analyzing protein sequence data becomes increasingly important recently. Most previous work on this area has mainly focused on building classification models. In this paper, we investigate in the problem of automatic clustering of unlabeled protein sequences. As a widely recognized technique in statistics and computer science, clustering has been proven very useful in detecting unknown object categories and revealing hidden correlations among objects. One difficulty that prevents clustering from being performed directly on protein sequence is the lack of an effective similarity measure that can be computed efficiently. Therefore, we propose a novel model for protein sequence cluster by exploring significant statistical properties possessed by the sequences. The concept of imprecise probabilities are introduced to the original probabilistic suffix tree to monitor the convergence of the empirical measurement and to guide the clustering process. It has been demonstrated that the proposed method can successfully discover meaningful families without the necessity of learning models of different families from pre-labeled "training data".

Algorithms↗
PubMed1989

Flagellar switch of Salmonella typhimurium: gene sequences and deduced protein sequences.

The fliG, fliM, and fliN genes of Salmonella typhimurium encode flagellar components that participate in energy transduction and switching. We have cloned these genes and determined their sequences. The deduced amino acid sequences correspond to proteins with molecular masses of 36,809, 37,815, and 14,772 daltons, respectively. None of the protein sequences are especially hydrophobic or look as though they correspond to integral membrane proteins, a result consistent with other evidence suggesting that the proteins may be peripheral to the membrane, possibly mounted onto the basal body M ring. The fliL gene, which immediately precedes fliM, is of unknown function; it encodes a protein with a deduced molecular mass of 17,082 daltons. The hydropathy profile of FliL indicates that it is likely to be an integral membrane protein with at least one spanning segment, near its N terminus. None of the four proteins exhibit consensus N-terminal signal sequences. Comparison of the fliL, fliM, and fliN sequences with the homologous ones in Escherichia coli reveals ranges of similarities of 77 to 95% at the amino acid level and 75 to 86% at the nucleotide level, with the majority (58 to 89%) of codon changes being synonymous ones.

Amino Acid Sequence↗
PubMed1996

Isolation and characterization of the mitochondrial ATP synthase from Chlamydomonas reinhardtii. cDNA sequence and deduced protein sequence of the alpha subunit.

We have isolated the F0F1-ATP synthase complex from oligomycin-sensitive mitochondria of the green alga Chlamydomonas reinhardtii. A pure and active ATP synthase was obtained by means of sonication, extraction with dodecyl maltoside and ion exchange and gel permeation chromatography in the presence of glycerol, DTT, ATP and PMSF [corrected]. The enzyme consists of 14 subunits as judged by SDS-PAGE. A cDNA clone encoding the ATP synthase alpha subunit has been sequenced. The deduced protein sequence contains a presequence of 45 amino acids which is not present in the mature protein. The mature protein is 58-70% identical to corresponding mitochondrial proteins from other organisms. In contrast to the ATP synthase beta subunit from C. reinhardtii (Franzen and Falk, Plant Mol Biol 19 (1992) 771-780), the protein does not have a C-terminal extension. However, the N-terminal domain of the mature protein is 15-18 residues longer than in ATP synthase alpha subunits from other organisms. Southern blot analysis indicates that the protein is encoded by a single-copy gene.

Amino Acid Sequence↗
PubMed2006

LPC cepstral distortion measure for protein sequence comparison.

Protein sequence comparison is the most powerful tool for the inference of novel protein structure and function. This type of inference is commonly based on the similar sequence-similar structure-similar function paradigm, and derived by sequence similarity searching on databases of protein sequences. As entire genomes have been being determined at a rapid rate, computational methods for comparing protein sequences will be more essential for probing the complexity of molecular machines. In this paper we introduce a pattern-comparison algorithm, which is based on the mathematical concepts of linear predictive coding (LPC) and LPC cepstral distortion measure, for computing similarities/dissimilarities between protein sequences. Experimental results on a real data set of functionally related and functionally nonrelated protein sequences have shown the effectiveness of the proposed approach on both accuracy and computational efficiency.

Algorithms↗
PubMed1998

Improving the recovery of lysine in automated protein sequencing.

Automated protein sequencing is an important tool in protein characterization. Most instruments use tetrahydrofuran (THF) as the HPLC eluent for separation of the derivatized amino acids residues. THF is highly perishable when exposed to air, generating peroxides which can degrade amino acids, mainly lysine, leading to uncertainty in chromatogram interpretations. Modifications of the existing HPLC equipment were introduced to create a permanent inert atmosphere inside the bottle of THF solution. This was carried out by changing the argon plumbing and some electrical connections and by reprogramming the software of the protein sequencer. The positive results of this procedure were demonstrated by comparing the decreasing lysine peak area during 28 days before and after the modifications. In the modified instrument, lysine recovery was much better as a function of the age of the THF eluent. Since these modifications improved the instrument performance, they have been adopted for routine use in our laboratory.

Amino Acid Sequence↗
PubMed1996

Fast comparison of a DNA sequence with a protein sequence database.

We describe a computer program, named DNA-Protein Search (DPS), for comparing a megabase DNA sequence with a protein sequence database. The DPS program addresses the problems of frameshifts and introns in the DNA sequence. The DPS program was used to compare each of the following sequences with the Swiss-Prot database: the 1.8-megabase sequence of the Haemophilus influenzae Rd genome, the 0.58-megabase sequence of the Mycoplasma genitalium genome, and the 0.56-megabase sequence of Saccharomyces cerevisiae chromosome VIII. The comparisons found new regions that are similar to protein sequences. The sensitivity of DPS was evaluated using as test data the known coding regions of the three DNA sequences. The results demonstrate that the DPS program is a useful tool for finding the coding regions of the DNA sequence. The DPS program uses an order of magnitude less computer memory and is several times faster than the BLASTX program.

Amino Acid Sequence↗