A system for the inducible secretion of proteins from Bacillus subtilis during logarithmic growth

Abstract A Bacillus subtilis-Escherichia coli shuttle vector was constructed containing the B. subtilis levansucrase gene promoter and region encoding its signal sequence.
A site for the restriction enzyme Nae I was included to facilitate precise translational fusions to the DNA encoding the levansucrase signal sequence. Fusions of TEM β-lactamase to this construct displayed sucrose-inducible expression and secretion of B. subtilis .     

Crystallization and preliminary X-ray diffraction study of an endoglucanase from Clostridium thermocellum

Endoglucanase D, a cellulose degradation enzyme from Clostridium thermocellum has been cloned in Escherichia coli, purified and crystallized. The crystals are trigonal, space group P3(1)12 (or P3(2)12) with a = 57.7 (+/- 0.1) A, c = 192.1 (+/- 0.2) A, and diffract X-rays to a resolution of 2.8 A. They are suitable for a high-resolution X-ray diffraction analysis.     

Lipid metabolism in the newborn genetically obese (fa/fa) rat

Compared to its lean litter mate (Fa/--) the Zucker rat (fa/fa) develops obesity without hyperphagia in the first week of lite. It is characterized by adipocyte hypertrophy and higher lipid content in adipose tissue. In vitro utilization as well as in vitro oxidation by diaphragm of palmitic acid was decreased in 1 week old Zucker rat.     

Nucleotide sequence of the cellulase gene celD encoding endoglucanase D of Clostridium thermocellum.

The nucleotide sequence of the celD gene, encoding the previously crystallized endoglucanase D of Clostridium thermocellum, is reported. The enzyme shares a conserved, reiterated domain with the COOH-terminal end of endoglucanases A and B from the same organism. The overexpression in Escherichia coli of celD subcloned in pUC8 appears to result from a translational fusion of the NH2-terminal end of the endoglucanase with the NH2-terminal end of beta-galactosidase.     

Cloning and nucleotide sequence of the csp1 gene encoding PS1, one of the two major secreted proteins of Corynebacterium glutamicum: the deduced N-terminal region of PS1 is similar to the Mycobacterium antigen 85 complex

Two proteins, PS1 and PS2, were detected in the culture medium of Corynebacterium glutamicum and are the major proteins secreted by this bacterium. No enzymatic activity was identified for either of the two proteins. Immunologically cross-reacting proteins were found in a variety of C. glutamicum strains but not in the coryneform Arthrobacter aureus. The gene encoding PS1, csp1, was cloned in lambda gt11 using polyclonal antibodies raised against PS1 to screen for producing clones. The csp1 gene was expressed in Escherichia coli, presumably from its own promoter, and directed the synthesis of two proteins recognized by anti-PS1 antibodies. The major protein band, of lower M(r), was detected in the periplasmic fraction. It had the same M(r) as the PS1 protein band detected in the supernatant of C. glutamicum cultures and presumably corresponds to the mature form of PS1. The minor protein band appears to be the precursor form of PS1. The nucleotide sequence of the csp1 gene was determined and contained an open reading frame encoding a polypeptide with a calculated molecular weight of 70,874, with a putative signal peptide with a molecular weight of 4411. This is consistent with the M(r) determined for PS1 from C. glutamicum culture supernatant and E. coli whole-cell extracts. The NH2-half of the deduced amino acid is similar (about 33% identical residues and 52% including similar residues) to the secreted antigen 85 protein complex of Mycobacterium. The csp1 gene in C. glutamicum was disrupted without any apparent effect on growth or viability.     

Inducible Secretion of a Cellulase from Clostridium thermocellum in Bacillus subtilis

A host-vector system for inducible secretion during the logarithmic growth phase in Bacillus subtilis has been developed. The B. subtilis levansucrase gene promoter and the region encoding its signal sequence have been used. The endoglucanase A of Clostridium thermocellum was used as a model protein to test the efficiency of the system. Effective inducible secretion of the endoglucanase A was observed when either the levansucrase signal sequence or its own signal sequence was used. Expression of the endoglucanase A in different genetic backgrounds of B. subtilis showed that its regulation was similar to that of levansucrase, and high enzyme activity was recovered from the culture supernatant of a hyperproducing B. subtilis sacU(Hy) strain. The molecular weight of 46,000 estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the secreted endoglucanase A is compatible with the calculated molecular weight of the mature polypeptide.     

Characterization of the cspB gene encoding PS2, an ordered surface-layer protein in Corynebacterium glutamicum

PS2 is one of two major proteins detected in the culture media of various Corynebacterium glutamicum strains. The coding and promoter regions of the cspB gene encoding PS2 were cloned in lambda gt11 using polyclonal antibodies raised against PS2 for screening. Expression of the cspB gene in Escherichia coli led to the production of a major anti-PS2 labelled peptide of 63 000 Da, corresponding presumably to the mature form of PS2. It was detected in the cytoplasm, periplasm and surrounding medium of E. coli. Three other slower migrating bands of 65000, 68 000 and 72 000 Da were detected. The largest one probably corresponds to the precursor form of PS2 in E. coli. Analysis of the nucleotide sequence revealed an open reading frame (ORF) of 1533 nucleotides. The deduced 510-amino-acid polypeptide had a calculated molecular mass of 55 426 Da. According to the predicted amino acid sequence, PS2 is synthesized with a W-terminal segment of 30-amino-acid residues reminiscent of eukaryotic and prokaryotic signal pep-tides, and a hydrophobic domain of 21 residues near the C-terminus. Although no significant homologies were found with other proteins, it appears that some characteristics and the amino acid composition of PS2 share several common features with surface-layer proteins. The cspB gene was then disrupted in C. glutamicum by gene replacement. Freeze-etching electron microscopy performed on the wild-type strain indicated that the cell wall of C. glutamicum is covered with an ordered surface of proteins (surface layer, S-layer) which is in very close contact with other cell-wall components. These structures are absent from the cspB-disrupted strain but are present after reintroduction of the cspB gene on a plasmid into this mutant. Thus we demonstrate that the Slayer protein is the product of the cspB gene.     

Secretion of an active recombinant dog gastric lipase from baculovirus-infected insect cells

An active dog gastric lipase (DGL) belonging to the acid-stable mammalian lipase family, was produced and secreted from baculovirus-infected insect cells using the honeybee melittin and the DGL signal sequences. Both sequences drove the secretion of an active 47 kDa recombinant DGL (rDGL). rDGL was secreted at about 35 mg/L of culture medium. A one step purification using a cation exchange chromatography was used to recover an active electrophoretically pure rDGL from 2 days post-infection supernatant. There were not significant differences between the enzymatic properties of native and recombinant proteins. © Rapid Science Ltd. 1998