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Motif programming: a microgene-based method for creating synthetic proteins containing multiple functional motifs.

ABSTRACT: The presence of peptide motifs within the proteins provides the synthetic biologist with the opportunity to fabricate novel proteins through the programming of these motifs. Here we describe a method that enables one to combine multiple peptide motifs to generate a combinatorial protein library. With this method, a set of sense and antisense oligonucleotide primers were prepared. These primers were mixed and polymerized, so that the resultant DNA consisted of combinatorial polymers of multiple microgenes created from the stochastic assembly of the sense and antisense primers. With this motif-mixing method, we prepared a protein library from the BH1-4 motifs shared among Bcl-2 family proteins. Among the 41 clones created, 70% of clones had a stable, presumably folded expression product in human cells, which was detectable by immunohistochemistry and western blot. The proteins obtained varied with respect to both the number and the order of the four motifs. The method enables homology-independent polymerization of DNA blocks that coded motif sequences, and the frequency of each motif within a library can be adjusted in a tailor-made manner. This motif programming has a potential for creating a library with a large proportion of folded/functional proteins.

SUBMITTER: Saito H

PROVIDER: S-EPMC1874597 | biostudies-literature | 2007

REPOSITORIES: biostudies-literature

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Motif programming: a microgene-based method for creating synthetic proteins containing multiple functional motifs.

Saito Hirohide H Minamisawa Tamiko T Shiba Kiyotaka K

Nucleic acids research 20070207 6

The presence of peptide motifs within the proteins provides the synthetic biologist with the opportunity to fabricate novel proteins through the programming of these motifs. Here we describe a method that enables one to combine multiple peptide motifs to generate a combinatorial protein library. With this method, a set of sense and antisense oligonucleotide primers were prepared. These primers were mixed and polymerized, so that the resultant DNA consisted of combinatorial polymers of multiple m ...[more]

PMID: 17287291

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Project description:GGGGCC repeat expansions of C9orf72 represent the most common genetic variant of amyotrophic lateral sclerosis and frontotemporal degeneration, but the mechanism of pathogenesis is unclear. Recent reports have suggested that the transcribed repeat might form toxic RNA foci that sequester various RNA processing proteins. Consensus as to the identity of the binding partners is missing and whole neuronal proteome investigation is needed. Using RNA fluorescence in situ hybridization we first identified nuclear and cytoplasmic RNA foci in peripheral and central nervous system biosamples from patients with amyotrophic lateral sclerosis with a repeat expansion of C9orf72 (C9orf72+), but not from those patients without a repeat expansion of C9orf72 (C9orf72-) or control subjects. Moreover, in the cases examined, the distribution of foci-positive neurons correlated with the clinical phenotype (t-test P < 0.05). As expected, RNA foci are ablated by RNase treatment. Interestingly, we identified foci in fibroblasts from an asymptomatic C9orf72+ carrier. We next performed pulldown assays, with GGGGCC5, in conjunction with mass spectrometry analysis, to identify candidate binding partners of the GGGGCC repeat expansion. Proteins containing RNA recognition motifs and involved in splicing, messenger RNA nuclear export and/or translation were significantly enriched. Immunohistochemistry in central nervous system tissue from C9orf72+ patients with amyotrophic lateral sclerosis demonstrated co-localization of RNA foci with SRSF2, hnRNP H1/F, ALYREF and hnRNP A1 in cerebellar granule cells and with SRSF2, hnRNP H1/F and ALYREF in motor neurons, the primary target of pathology in amyotrophic lateral sclerosis. Direct binding of proteins to GGGGCC repeat RNA was confirmed in vitro by ultraviolet-crosslinking assays. Co-localization was only detected in a small proportion of RNA foci, suggesting dynamic sequestration rather than irreversible binding. Additional immunohistochemistry demonstrated that neurons with and without RNA foci were equally likely to show nuclear depletion of TDP-43 (?(2) P = 0.75) or poly-GA dipeptide repeat protein inclusions (?(2) P = 0.46). Our findings suggest two non-exclusive pathogenic mechanisms: (i) functional depletion of RNA-processing proteins resulting in disruption of messenger RNA splicing; and (ii) licensing of expanded C9orf72 pre-messenger RNA for nuclear export by inappropriate association with messenger RNA export adaptor protein(s) leading to cytoplasmic repeat associated non-ATG translation and formation of potentially toxic dipeptide repeat protein.

Project description:We have recently shown that synthetic peptides of the effector domain of the low-molecular-mass GTP-binding protein Rab3 stimulate inositol 1,4,5-trisphosphate production in various permeabilized cells. To investigate the mechanism of the peptide-induced activation of phospholipase C (PLC) and to identify the PLC isoenzyme(s) targeted by these peptides, isolated pancreatic acinar membranes and cytosol were preincubated with anti-PLC antibodies before examination of PLC activity in response to the Rab3B/D effector-domain peptide (VSTVGIDFKVKTVYRH, peptide P1). Western blot analysis revealed the presence of PLC-beta1, -beta3, -gamma1 and -delta1 in membrane and cytosolic fractions. P1 stimulated PLC activity in both membrane and cytosolic fractions. Anti-(PLC-beta1) antibody inhibited P1-induced PLC activity in both subcellular fractions almost completely. Moreover, P1-induced amylase release in digitonin-permeabilized pancreatic acini was also inhibited. Other immunoneutralizing anti-PLC antibodies had no effect, suggesting that P1 activates PLC-beta1 but not PLC-beta3, -gamma1 or -delta1. P1 also activated recombinant PLC-beta1, indicating direct activation of PLC-beta1 by Rab3 effector-domain peptides. To investigate further the structure-function relationship of the peptides, truncated peptides of P1 were tested for their ability to activate PLC in isolated pancreatic acinar membranes and to stimulate amylase release from digitonin-permeabilized pancreatic acini. Peptides containing a BXBXXXB(B) motif (where B represents a basic residue and X any residue)[KVKTVYRH (EC50 of 1 nM to stimulate amylase release) approximately TVGIDFKVKTVYRH > TVGIDFKVKTVYR] were potent stimulators of amylase release and PLC activity, whereas deletion of the C-terminus (VSTVGIDF), of the two basic C-terminal amino acid residues (VSTVGIDFKVKTVY and KVKTVY), or destruction of the BXB motif (VKTVYR) resulted in inactive peptides. In conclusion, the results of the present study show that short peptides containing a BXBXXXB motif represent promising pharmacological agents to activate the PLC-beta1 isoenzyme.

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Motif programming: a microgene-based method for creating synthetic proteins containing multiple functional motifs.

Publications

Motif programming: a microgene-based method for creating synthetic proteins containing multiple functional motifs.

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