Basic Vector Information
The pMAL-4 vectors (Figure 1) provide a method for expressing and purifying a protein produced from a cloned gene or open reading frame. The cloned gene is inserted downstream from the malE gene of E. coli, which encodes maltose-binding protein (MBP), resulting in the expression of an MBP fusion protein (1,2). The MBP in these vectors has been engineered for tighter binding to amylose. The method uses the strong “tac” promoter and the malE translation initiation signals to give high-level expression of the cloned sequences (3,4), and a one-step purification of the fusion protein using MBP’s affinity for maltose (5). The vectors express the malE gene (with or without its signal sequence) fused to the lacZα gene. Restriction sites between malE and lacZα are available for inserting the coding sequence of interest. Insertion inactivates the β-galactosidase α-fragment activity of the malE-lacZα fusion, which results in a blue to white color change on Xgal plates when the construction is transformed into an α-complementing host such as TB1, JM107 or NEB 5-alpha Competent E. coli (6,7). When present, the signal peptide on pre-MBP directs fusion proteins to the periplasm. For fusion proteins that can be successfully exported, this allows folding and disulfide bond formation to take place in the periplasm of E. coli, as well as allowing purification of the protein from the periplasm (8). The vectors carry the lacIq gene, which codes for the Lac repressor. This keeps expression from Ptac low in the absence of IPTG induction. The pMAL-4 vectors also contain the sequence coding for the recognition site of a specific protease, located just 5´ to the polylinker insertion sites. This allows MBP to be cleaved from the protein of interest after purification. The pMAL-c4X and pMAL-p4X vectors that are included in the system encode the site for Factor Xa (9, 10). Factor Xa cleaves after its four amino acid recognition sequence, so that few or no vector-derived residues are attached to the protein of interest, depending on the site used for cloning. pMAL vectors containing sites for alternative proteases are also available (Figure 1). The vectors pMAL-c4G (NEB #N8106) and pMAL-p4G (NEB #N8103) encode the site for GenenaseI (NEB #P8075), which cleaves following the sequence His-Tyr. The vectors pMAL-c4E (NEB #N8105) and pMAL-p4E (NEB #N8102) encode the site for Enterokinase (NEB #P8070), which cleaves following the sequence Asp-Asp-Asp-Asp-Lys.
- Vector Name:
- pMAL-p4x
- Antibiotic Resistance:
- Ampicillin
- Length:
- 6720 bp
- Type:
- E. coli Expression Vectors
- Replication origin:
- ori
- Copy Number:
- High copy number
- Promoter:
- Tac
- Cloning Method:
- Enzyme digestion and ligation
- 5' Primer:
- MalE: 5'-GGTCGTCAGACTGTCGATGAAGCC-3'; MBP-F: 5'-gatgaagccctgaaagacgcgcag-3'
- 3' Primer:
- pBad-R: 5'-gatttaatctgtatcagg-3'; M13-F: 5'-TGTAAAACGACGGCCAGT-3'
- Fusion Tag:
- N-MBP, N-Factor Xa
pMAL-p4x vector Vector Map
Plasmid Resuspension Protocol:
1. Centrifuge at 5,000×g for 5 min.
2. Carefully open the tube and add 20 μl of sterile water to dissolve the DNA.
3. Close the tube and incubate for 10 minutes at room temperature.
4. Briefly vortex the tube and then do a quick spin to concentrate the liquid at the bottom. Speed is less than 5000×g.
5.Store the plasmid at -20 ℃.
pMAL-p4x vector Sequence
LOCUS 40924_29746 6720 bp DNA circular SYN 13-JAN-2022 DEFINITION synthetic circular DNA. ACCESSION . VERSION . KEYWORDS . SOURCE synthetic DNA construct ORGANISM synthetic DNA construct REFERENCE 1 (bases 1 to 6720) TITLE Direct Submission REFERENCE 2 (bases 1 to 6720) AUTHORS . TITLE Direct Submission COMMENT SGRef: number: 1; type: "Journal Article" FEATURES Location/Qualifiers source 1..6720 /mol_type="other DNA" /organism="synthetic DNA construct" promoter 3..80 /label=lacIq promoter /note="In the lacIq allele, a single base change in the promoter boosts expression of the lacI gene about 10-fold." CDS 81..1160 /codon_start=1 /label=lacI /note="lac repressor" /translation="VKPVTLYDVAEYAGVSYQTVSRVVNQASHVSAKTREKVEAAMAEL NYIPNRVAQQLAGKQSLLIGVATSSLALHAPSQIVAAIKSRADQLGASVVVSMVERSGV EACKAAVHNLLAQRVSGLIINYPLDDQDAIAVEAACTNVPALFLDVSDQTPINSIIFSH EDGTRLGVEHLVALGHQQIALLAGPLSSVSARLRLAGWHKYLTRNQIQPIAEREGDWSA MSGFQQTMQMLNEGIVPTAMLVANDQMALGAMRAITESGLRVGADISVVGYDDTEDSSC YIPPLTTIKQDFRLLGQTSVDRLLQLSQGQAVKGNQLLPVSLVKRKTTLAPNTQTASPR ALADSLMQLARQVSRLESGQ" protein_bind 1176..1197 /label=CAP binding site /note="CAP binding activates transcription in the presence of cAMP." promoter 1406..1434 /label=tac promoter /note="strong E. coli promoter; hybrid between the trp and lac UV5 promoters" protein_bind 1442..1458 /label=lac operator /note="The lac repressor binds to the lac operator to inhibit transcription in E. coli. This inhibition can be relieved by adding lactose or isopropyl-beta-D-thiogalactopyranoside (IPTG)." CDS 1528..2703 /codon_start=1 /label=MBP /note="maltose binding protein from E. coli" /translation="MKIKTGARILALSALTTMMFSASALAKIEEGKLVIWINGDKGYNG LAEVGKKFEKDTGIKVTVEHPDKLEEKFPQVAATGDGPDIIFWAHDRFGGYAQSGLLAE ITPDKAFQDKLYPFTWDAVRYNGKLIAYPIAVEALSLIYNKDLLPNPPKTWEEIPALDK ELKAKGKSALMFNLQEPYFTWPLIAADGGYAFKYENGKYDIKDVGVDNAGAKAGLTFLV DLIKNKHMNADTDYSIAEAAFNKGETAMTINGPWAWSNIDTSKVNYGVTVLPTFKGQPS KPFVGVLSAGINAASPNKELAKEFLENYLLTDEGLEAVNKDKPLGAVALKSYEEELVKD PRIAATMENAQKGEIMPNIPQMSAFWYAVRTAVINAASGRQTVDEALKDAQT" CDS 2752..2763 /codon_start=1 /label=Factor Xa site /note="Factor Xa recognition and cleavage site" /translation="IEGR" primer_bind complement(2811..2827) /label=M13 fwd /note="common sequencing primer, one of multiple similar variants" terminator 3176..3262 /label=rrnB T1 terminator /note="transcription terminator T1 from the E. coli rrnB gene" terminator 3354..3381 /label=rrnB T2 terminator /note="transcription terminator T2 from the E. coli rrnB gene" promoter 3400..3491 /label=AmpR promoter CDS 3492..4349 /codon_start=1 /label=AmpR /note="beta-lactamase" /translation="MSIQHFRVALIPFFAAFCLPVFAHPETLVKVKDAEDQLGARVGYI ELDLNSGKILESFRPEERFPMMSTFKVLLCGAVLSRVDAGQEQLGRRIHYSQNDLVEYS PVTEKHLTDGMTVRELCSAAITMSDNTAANLLLTTIGGPKELTAFLHNMGDHVTRLDRW EPELNEAIPNDERDTTMPVAMATTLRKLLTGELLTLASRQQLIDWMEADKVAGPLLRSA LPAGWFIADKSGAGERGSRGIIAALGPDGKPSRIVVIYTTGSQATMDERNRQIAEIGAS LIKHW" rep_origin complement(4394..4907) /direction=LEFT /label=M13 ori /note="M13 bacteriophage origin of replication; arrow indicates direction of (+) strand synthesis" rep_origin 5018..5606 /label=ori /note="high-copy-number ColE1/pMB1/pBR322/pUC origin of replication" misc_feature complement(5792..5934) /label=bom /note="basis of mobility region from pBR322" CDS complement(6039..6227) /codon_start=1 /label=rop /note="Rop protein, which maintains plasmids at low copy number" /translation="VTKQEKTALNMARFIRSQTLTLLEKLNELDADEQADICESLHDHA DELYRSCLARFGDDGENL"
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