Expression of mature pulmonary surfactant-associated protein B (SP-B) in Escherichia coli using truncated human SP-B cDNAs.
The present communication documents attempts to produce the mature form of human surfactant-associated protein B (SP-B) by modification of the 5' and 3' regions of the cDNA and expression of the truncated cDNAs after insertion into the vector pKK223-3. The 5' end of a cDNA for human SP-B (1407 base pairs) was reconstructed through the ligation of synthetic oligonucleotides to an internal PstI site in the 5' region. This construction coded for the initiation of protein synthesis at a Met codon adjacent to a codon for the N-terminal Phe of the mature polypeptide. Variable amounts of the 3' end of the human SP-B cDNA were deleted with mung bean nuclease and exonuclease III. The resulting blunt-ended 3' fragments were then ligated to a synthetic oligonucleotide linker designed to create a stop codon. The modified 5' and 3' ends were ligated to a short PstI-BamHI fragment isolated from the SP-B cDNA and inserted into the expression vector pKK223-3. In vitro translation of sense mRNAs derived from the truncated SP-B cDNAs yielded oligopeptides of appropriate molecular weights, as indicated by urea - sodium dodecyl sulphate - polyacrylamide gel electrophoresis of either intact or immunoprecipitated reaction mixtures. Expression of SP-B in Escherichia coli was confirmed by Northern blot analysis for the mRNAs corresponding to the truncated cDNAs in appropriately transformed bacteria induced with the galactose analog isopropyl-beta-thiogalactoside. Western blot analysis using rabbit antisera prepared against bovine SP-B confirmed the presence of mature SP-B in lipid extracts of transformed E. coli, but the amounts were very small.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Obstetrics and Gynaecology, University of Western Ontario, London, Canada.
L J
LJ
Yao
C
C
Richardson
C
C
Ford
N
N
Mathialagan
G
G
Mackie
G L
GL
Hammond
P G
PG
Harding
F
F
Possmayer
D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011510:Proteolipids / Q000235:genetics*; D011663:Pulmonary Surfactants / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics
D011510:Proteolipids; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; D011994:Recombinant Proteins; D004247:DNA