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Karnik A, Karnik R, Grefen C. SDM-Assist software to design site-directed mutagenesis primers introducing "silent" restriction sites. BMC Bioinformatics 2013; 14:105. [PMID: 23522286 PMCID: PMC3644487 DOI: 10.1186/1471-2105-14-105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/19/2013] [Indexed: 11/16/2022] Open
Abstract
Background Over the past decades site-directed mutagenesis (SDM) has become an indispensable tool for biological structure-function studies. In principle, SDM uses modified primer pairs in a PCR reaction to introduce a mutation in a cDNA insert. DpnI digestion of the reaction mixture is used to eliminate template copies before amplification in E. coli; however, this process is inefficient resulting in un-mutated clones which can only be distinguished from mutant clones by sequencing. Results We have developed a program – ‘SDM-Assist’ which creates SDM primers adding a specific identifier: through additional silent mutations a restriction site is included or a previous one removed which allows for highly efficient identification of ‘mutated clones’ by a simple restriction digest. Conclusions The direct identification of SDM clones will save time and money for researchers. SDM-Assist also scores the primers based on factors such as Tm, GC content and secondary structure allowing for simplified selection of optimal primer pairs.
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Affiliation(s)
- Abhijit Karnik
- Department of Computer Science, University of Bristol, Bristol, UK
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2
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Evans PM, Liu C. SiteFind: a software tool for introducing a restriction site as a marker for successful site-directed mutagenesis. BMC Mol Biol 2005; 6:22. [PMID: 16321147 PMCID: PMC1314889 DOI: 10.1186/1471-2199-6-22] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Accepted: 12/01/2005] [Indexed: 11/25/2022] Open
Abstract
Background Site-directed mutagenesis is a widely-used technique for introducing mutations into a particular DNA sequence, often with the goal of creating a point mutation in the corresponding amino acid sequence but otherwise leaving the overall sequence undisturbed. However, this method provides no means for verifying its success other than sequencing the putative mutant construct: This can quickly become an expensive method for screening for successful mutations. An alternative to sequencing is to simultaneously introduce a restriction site near the point mutation in manner such that the restriction site has no effect on the translated amino acid sequence. Thus, the novel restriction site can be used as a marker for successful mutation which can be quickly and easily assessed. However, finding a restriction site that does not disturb the corresponding amino acid sequence is a time-consuming task even for experienced researchers. A fast and easy to use computer program is needed for this task. Results We wrote a computer program, called SiteFind, to help us design a restriction site within the mutation primers without changing the peptide sequence. Because of the redundancy of genetic code, a given peptide can be encoded by many different DNA sequences. Since the list of possible restriction sites for a given DNA sequence is not always obvious, SiteFind automates this task. The number of possible sequences a computer program must search through increases exponentially as the sequence length increases. SiteFind uses a novel "moving window" algorithm to reduce the number of possible sequences to be searched to a manageable level. The user enters a nucleotide sequence, specifies what amino acid residues should be changed in the mutation, and SiteFind generates a list of possible restriction sites and what nucleotides must be changed to introduce that site. As a demonstration of its use, we successfully generated a single point mutation and a double point mutation in the wild-type sequence for Krüppel-like factor 4, an epithelium-specific transcription factor. Conclusion SiteFind is an intuitive, web-based program that enables the user to introduce a novel restriction site into the mutated nucleotide sequence for use as a marker of successful mutation. It is freely available from
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Affiliation(s)
- Paul M Evans
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, USA
- Sealy Center for Cancer Cell Biology, University of Texas Medical Branch, Galveston, USA
| | - Chunming Liu
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, USA
- Sealy Center for Cancer Cell Biology, University of Texas Medical Branch, Galveston, USA
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He X, Shen L, Dahlbäck B. Expression and functional characterization of chimeras between human and bovine vitamin-K-dependent protein-S-defining modules important for the species specificity of the activated protein C cofactor activity. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 227:433-40. [PMID: 7851419 DOI: 10.1111/j.1432-1033.1995.tb20406.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Vitamin-K-dependent protein S is an anticoagulant plasma protein functioning as a cofactor to activated protein C (APC) in the degradation of factors Va and VIIIa. The APC-cofactor function of protein S is species specific, as human protein S potentiates the anticoagulant activity of human but not that of bovine APC, whereas bovine protein S is a cofactor to APC from both species. To elucidate which modules in protein S determine the species specificity, in vitro mutagenesis was used to construct six recombinant chimeric molecules between human and bovine protein S. Wild-type human and bovine protein S and the chimeras were expressed in 293 cells and the recombinant proteins purified by monoclonal antibody affinity chromatography. The recombinant proteins were found to be post-translationally modified, they bound C4b-binding protein and were functionally active as cofactors to APC. Chimeras having both the thrombin-sensitive region (TSR) and the first epidermal-growth-factor-(EGF)-like module of bovine origin expressed APC-cofactor activity similar to that of bovine protein S. Those chimeras, in which TSR or EGF1 derived from different species, manifested APC-cofactor activity similar to that of human protein S, i.e. they did not express cofactor activity to bovine APC. These data indicate that sequence differences in the TSR and EGF1 of human and bovine protein S cause the species specificity of the APC-cofactor activity. The data support the concept that these two modules of protein S interact with APC on the surface of negatively charged phospholipids.
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Affiliation(s)
- X He
- Department of Clinical Chemistry, Lund University, Malmö General Hospital, Sweden
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4
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Affiliation(s)
- J W Little
- Department of Biochemistry and Molecular and Cellular Biology, University of Arizona, Tucson 85721
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5
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Abstract
Deletion mutagenesis in bacteriophage T7 was studied with an insertion-reversion assay involving phage containing inserts of foreign DNA that form 10-bp direct repeats. The precise deletion of the insert restores the function of the non-essential gene and is easily assayed by growth on selection strains of E. coli. Similar inserts with unique direct repeats were placed in either gene 1.2 (dGTPase Inhibitor) or gene 1.3 (DNA ligase). The deletion rates of the inserts were quantified with Luria and Delbrück fluctuation tests. Deletion rates were similar for inserts in both genes indicating that the rates of deletion were not unique to either specific site, or the sequence of the direct repeats. Deletion was independent of functional T7 ligase at 37 degrees C, while an increase in the rate of deletion was noted in some ligase-deficient phage at 43 degrees C. The effect of E. coli DNA Polymerase I on deletion rate was tested and found to decrease deletion rate 60% with the polA1 mutation and 90% with the polA546ex mutation.
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Affiliation(s)
- L M Scearce
- Temple University School of Medicine, Department of Biochemistry and Molecular Biology, Philadelphia, PA 19140
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6
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Rivera M, Barillas-Mury C, Christensen KA, Little JW, Wells MA, Walker FA. Gene synthesis, bacterial expression, and 1H NMR spectroscopic studies of the rat outer mitochondrial membrane cytochrome b5. Biochemistry 1992; 31:12233-40. [PMID: 1333795 DOI: 10.1021/bi00163a037] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The gene coding for the water-soluble domain of the outer mitochondrial membrane cytochrome b5 (OM cytochrome b5) from rat liver has been synthetized and expressed in Escherichia coli. The DNA sequence was obtained by back-translating the known amino acid sequence [Lederer, F., Ghrir, R., Guiard, B., Cortial, S., & Ito, A. (1983) Eur. J. Biochem. 132, 95-102]. The recombinant OM cytochrome b5 was characterized by UV-visible, EPR, and 1H NMR spectroscopy. The UV-visible and EPR spectra of the OM cytochrome b5 are almost identical to the ones obtained from the overexpressed rat microsomal cytochrome b5 [Bodman, S. B. V., Schyler, M. A., Jollie, D. R., & Sligar, S. G. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 9443-9447]. The one-dimensional 1H NMR spectrum of the OM cytochrome b5 indicates that the rhombic perturbation of the ferric center is essentially identical to that in the microsomal beef, rabbit, chicken, and rat cytochromes b5. Two-dimensional 1H NMR spectroscopy (NOESY) and one-dimensional NOE difference spectroscopy were used to assign the contact-shifted resonances that correspond to each of the two isomers that result from the rotation of the heme around its alpha-gamma-meso axis. The assignment of the resonances allowed the determination of the heme orientation ratio in the OM cytochrome b5, which was found to be 1.0 +/- 0.1. It is noteworthy that the two cytochromes b5 that have similar populations of the two heme isomers (large heme disorder) originate from the rat liver.
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Affiliation(s)
- M Rivera
- Department of Chemistry, University of Arizona, Tucson 85721
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7
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Toomey J, Smith K, Stafford D. Localization of the human tissue factor recognition determinant of human factor VIIa. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54982-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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8
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Itaya M, Tanaka T. Complete physical map of the Bacillus subtilis 168 chromosome constructed by a gene-directed mutagenesis method. J Mol Biol 1991; 220:631-48. [PMID: 1908013 DOI: 10.1016/0022-2836(91)90106-g] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
All the SfiI sites and most of the NotI sites were located precisely on the chromosome of Bacillus subtilis 168 by a novel method, termed gene-directed mutagenesis. The stepwise elimination of these restriction sites by this method allowed not only the physical connection of the restriction fragments but also the accurate determination of the position of the restriction sites themselves. The resulting physical map of the 4165 x 10(3) base-pair B. subtilis chromosome has been correlated with the genetic map by determination of the exact location of known genes. The complete physical map provides a rapid and accurate way for mapping of new genes as well as analysis of large DNA rearrangements on the chromosome. The novel strategy is, in principle, applicable to the analysis of the genome of other organisms.
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Affiliation(s)
- M Itaya
- Department of Molecular Biology, Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan
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9
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In vitro gamma-carboxylation of a 59-residue recombinant peptide including the propeptide and the gamma-carboxyglutamic acid domain of coagulation factor IX. Effect of mutations near the propeptide cleavage site. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38275-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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10
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Little JW. Saturation mutagenesis of specific codons: elimination of molecules with stop codons from mixed pools of DNA. Gene 1990; 88:113-5. [PMID: 2341037 DOI: 10.1016/0378-1119(90)90067-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In saturation mutagenesis of a protein, pools of DNA molecules are made containing a mixture of codons at a specific position. In cases where genetic methods allow screens or selections for altered function, a background of nonsense mutations can complicate genetic analysis of the resulting mutations. Methods are proposed for elimination of those molecules containing stop codons at the target codon from the pool, and for identifying positions to which these methods may be applied. Application of these methods should ensure that all changes are missense mutations, thereby simplifying genetic analysis.
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Affiliation(s)
- J W Little
- Department of Biochemistry, University of Arizona, Tucson 85721
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11
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Expression and characterization of human factor IX and factor IX-factor X chimeras in mouse C127 cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)40207-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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12
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Lin LL, Little JW. Isolation and characterization of noncleavable (Ind-) mutants of the LexA repressor of Escherichia coli K-12. J Bacteriol 1988; 170:2163-73. [PMID: 2834329 PMCID: PMC211102 DOI: 10.1128/jb.170.5.2163-2173.1988] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The LexA repressor of Escherichia coli represses a set of genes that are expressed in the response to DNA damage. After inducing treatments, the repressor is inactivated in vivo by a specific cleavage reaction which requires an activated form of RecA protein. In vitro, specific cleavage requires activated RecA at neutral pH and proceeds spontaneously at alkaline pH. We have isolated and characterized a set of lexA mutants that are deficient in in vivo RecA-mediated cleavage but retain significant repressor function. Forty-six independent mutants, generated by hydroxylamine and formic acid mutagenesis, were isolated by a screen involving the use of operon fusions. DNA sequence analysis identified 20 different mutations. In a recA mutant, all but four of the mutant proteins functioned as repressor as well as wild-type LexA. In a strain carrying a constitutively active recA allele, recA730, all the mutant proteins repressed a sulA::lacZ fusion more efficiently than the wild-type repressor, presumably because they were cleaved poorly or not at all by the activated RecA protein. These 20 mutations resulted in amino acid substitutions in 12 positions, most of which are conserved between LexA and four other cleavable proteins. All the mutations were located in the hinge region or C-terminal domain of the protein, portions of LexA previously implicated in the specific cleavage reactions. Furthermore, these mutations were clustered in three regions, around the cleavage site (Ala-84-Gly-85) and in blocks of conserved amino acids around two residues, Ser-119 and Lys-156, which are believed essential for the cleavage reactions. These three regions of the protein thus appear to play important roles in the cleavage reaction.
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Affiliation(s)
- L L Lin
- Department of Biochemistry, University of Arizona, Tucson 85721
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Slilaty SN, Little JW. Lysine-156 and serine-119 are required for LexA repressor cleavage: a possible mechanism. Proc Natl Acad Sci U S A 1987; 84:3987-91. [PMID: 3108885 PMCID: PMC305006 DOI: 10.1073/pnas.84.12.3987] [Citation(s) in RCA: 173] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
LexA repressor of Escherichia coli is inactivated in vivo by a specific cleavage reaction requiring activated RecA protein. In vitro, cleavage requires activated RecA at neutral pH and proceeds spontaneously at alkaline pH. These two cleavage reactions have similar specificities, suggesting that RecA acts indirectly to stimulate self-cleavage, rather than directly as a protease. We have studied the chemical mechanism of cleavage by using site-directed mutagenesis to change selected amino acid residues in LexA, chosen on the basis of kinetic data, homology to other cleavable repressors, and potential similarity of the mechanism to that of proteases. Serine-119 and lysine-156 were changed to alanine, a residue with an unreactive side chain, resulting in two mutant proteins that had normal repressor function and apparently normal structure, but were completely deficient in both types of cleavage reaction. Serine-119 was also changed to cysteine, another residue with a nucleophilic side chain, resulting in a protein that was cleaved at a significant rate. These and other observations suggest that hydrolysis of the scissile peptide bond proceeds by a mechanism similar to that of serine proteases, with serine-119 being a nucleophile and lysine-156 being an activator. Possible roles for RecA are discussed.
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Myers EW, Mount DW. Computer program for the IBM personal computer which searches for approximate matches to short oligonucleotide sequences in long target DNA sequences. Nucleic Acids Res 1986; 14:501-8. [PMID: 3753785 PMCID: PMC339434 DOI: 10.1093/nar/14.1.501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We describe a program which may be used to find approximate matches to a short predefined DNA sequence in a larger target DNA sequence. The program predicts the usefulness of specific DNA probes and sequencing primers and finds nearly identical sequences that might represent the same regulatory signal. The program is written in the C programming language and will run on virtually any computer system with a C compiler, such as the IBM/PC and other computers running under the MS/DOS and UNIX operating systems. The program has been integrated into an existing software package for the IBM personal computer (see article by Mount and Conrad, this volume). Some examples of its use are given.
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15
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Mount DW, Conrad B. Improved programs for DNA and protein sequence analysis on the IBM personal computer and other standard computer systems. Nucleic Acids Res 1986; 14:443-54. [PMID: 3753780 PMCID: PMC339429 DOI: 10.1093/nar/14.1.443] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have previously described programs for a variety of types of sequence analysis (1-4). These programs have now been integrated into a single package. They are written in the standard C programming language and run on virtually any computer system with a C compiler, such as the IBM/PC and other computers running under the MS/DOS and UNIX operating systems. The programs are widely distributed and may be obtained from the authors as described below.
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