Transfer and expression of the cryIVB and cryIVD genes of Bacillus thuringiensis subsp. israelensis in Bacillus sphaericus 2297

Abstract The genes encoding the CryIVB and CryIVD crystal polypeptides of B. thuringiensis subsp. israelensis were cloned indepently on a stable shuttle vector, and transfered into B. sphaericus 2297. Recombinant cells expressed the B. thuringiensis toxins during sporulation and were shown to be toxic to Aedes aegypti fourth instar larvae, whereas the parental strain was not.     

Complement genes C1r and C1s feature an intronless serine protease domain closely related to haptoglobin

The exon-intron structure of the human complement C1s gene displays a striking similarity with that of the gene encoding haptoglobin, a peculiar transport protein distantly related to the serine proteases. While the protease regions of the serine zymogens are typically encoded by multiple exons, the protease domains of C1s and of its genetically linked and functionally interacting homolog C1r are encoded as intronless domains, not unlike a region of haptoglobin, which in fact is devoid of proteolytic activity. The close similarity of the C1s gene with haptoglobin includes the precise conservation of exon-intron junctions and it extends to upstream exons encoding the short repeats typical of several complement components, but found also in other functionally unrelated proteins. Additional evidence of the common ancestry of C1r, C1s and haptoglobin is the presence, within the protease domain, of a set of sequence markers that distinguish these three proteins from all known serine proteases. The finding of vertebrate serine protease genes with an uninterrupted protease-encoding exon supports the definition of a novel evolutionary branch of this gene family and rules out the hypothesis that regards this unusual exon as an irrelevant byproduct of the extravagant functional divergence of haptoglobin.     

The major 45-kDa protein of the yeast mitochondrial outer membrane is not essential for cell growth or mitochondrial function

As part of an analysis of the function and assembly of the mitochondrial outer membrane, we have cloned and characterized the yeast gene encoding a 45-kDa polypeptide (OM45) which is a major constituent of this membrane. The nuclear gene was isolated by immunological screening of plaques of recombinant phage lambda gt11 containing fragments of yeast genomic DNA using an antibody against OM45. Determination of the nucleotide sequence of the DNA fragment isolated by this approach revealed a single open reading frame of 1179 base pairs which encodes a protein having a predicted molecular mass of 44.6-kDa. Disruption of the OM45 gene in haploid yeast cells eliminated the expression of OM45. The mutant strain showed no apparent defect in cell viability, growth, mitochondrial function, or mitochondrial protein import.     

Arg74 in HLA-DRBI and DRB3 controls a DR3-related epitope

TR81 is a specificity closely related to or identical with DR3. In Caucasoids two amino acids, Tyr at position 26 and Arg at position 74 of HLA class II DR chains, have been found to be associated with the presence of TR81. Recently, a variant of DRBI *03 identified in American Blacks has been shown to possess Arg at position 74 but Phe at position 26. This codon combination is found to be present in four other cell lines where it still specifies the TR81 determinant. This suggests that the TR81 specificity is uniquely dependent on the presence of Arg at position 74.     

Amino acid transport in the rat exocrine pancreas

Summary Amino acid transport and incorporation have been studied in vitro in rat pancreatic lobules after maximal and supramaximal hormonal stimulation with caerulein. Incorporation into proteins was increased already after 30 and 120 min of maximal stimulation, but was decreased after the infusion of a supramaximal dose. Uptake of neutral amino acids was monitored using labeled leucine and -aminoisobutyric acid (AIB). In the case of leucine the free pool was consistently reduced after maximal stimulation, while supramaximal doses led to an increase which could be potentiated by the addition of 2mM tetracaine. Using AIB, a significant increase in the intracellular pool was observed after maximal stimulation, conversely a decrease after supramaximal stimulation. Release of labeled leucine and AIB from preloaded lobules during incubation in the cold was significantly reduced after maximal secretory stimulation, but was found enhanced by 200 to 300 percent after supramaximal stimulation. No fine structural alterations at junctional complexes or at both the lateral and luminal plasma membranes were observed after maximal stimulation except an increased number of exocytotic figures at the luminal face. However, supramaximal stimulation led to progressive rarefaction of the tight junctional network and disintegration of the gap junctions. Concomitantly, an equal distribution of membrane particles on both faces of the plasma membrane together with a random occurrence of exocytotic figures were observed.Supported by a grant from the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (SFB 122, project C 5). Dedicated to Professor Dr. Gerhard Petry, Marburg, on the occasion of his 65th birthday