PubMed Health⌕ Search

Biomedical subjects

B L Pasloske

Publications and source records attributed to B L Pasloske.

29 records · Page 2Linked to original sources
PubMed1990

Surface molecules on Plasmodium falciparum-infected erythrocytes involved in adherence.

The identity of cell surface receptor molecules on Plasmodium falciparum-infected erythrocytes is of great interest since the functional sites involved in attachment to endothelial cells may be structurally conserved in wild isolates. Such conserved sites may represent suitable antigenic targets for a vaccine-induced immune response that would block or reverse infected cell sequestration in vivo. Identification of the infected cell receptor sites may also lead to novel methods for treatment of acute cerebral malaria. We review the likely roles, either direct or indirect, for the participation of knob protrusions, malarial proteins expressed at the cell surface, and modified host membrane proteins in the specific receptor properties acquired by infected erythrocytes.

Animals↗
PubMed1989

The activity of the Pseudomonas aeruginosa pilin promoter is enhanced by an upstream regulatory site.

Recently, a comparison of the nucleotide sequences upstream of the structural pilin genes (pil) from five different isolates of Pseudomonas aeruginosa identified a sequence homologous to a NifA-binding site, a positive regulatory sequence in Klebsiella pneumoniae which controls the expression of the genes which fix nitrogen [Pasloske et al., J. Bacteriol. 170 (1988) 3738-3741]. This sequence was located between -98 and -114 bp relative to the transcription start point. To establish whether this putative recognition sequence exerted any regulatory effect on pil gene expression, we assayed for the expression of pilin and pili, and assessed the strength of the pilin promoter with and without this upstream sequence. A 48-bp deletion, which removed the putative recognition sequence, decreased the levels of pilin and pilus expression. Also, the equivalent deletion reduced pilin promoter activity by 90% when it was measured using a promoter probe vector. These results provide evidence that a nucleotide sequence upstream of the pilin promoter positively regulates the transcription of the P. aeruginosa pil gene.

Bacterial Outer Membrane Proteins↗
PubMed1989

Pseudomonas aeruginosa pili as ligands for nonopsonic phagocytosis by fibronectin-stimulated macrophages.

Fibronectin is capable of activating macrophages for enhanced nonopsonic phagocytosis of Pseudomonas aeruginosa grown in vivo in rats or mice or in vitro on nutrient agar plates. In this study it was determined that while fibronectin was able to significantly increase phagocytosis of organisms grown in static broth, uptake of agitated bacteria could not be promoted. Agitated P. aeruginosa cultures were proven to lack surface pili expression, as assessed by electron microscopic studies. A pilus-deficient pilA::Tn501 mutant of P. aeruginosa PAO was constructed by gene replacement techniques. Phagocytosis of this mutant could not be enhanced by fibronectin regardless of growth conditions. Furthermore, 60 micrograms of exogenously added Pseudomonas pili per ml was capable of abrogating the enhanced phagocytosis of the wild-type strain observed with fibronectin-stimulated macrophages. It is concluded that Pseudomonas pili were the bacterial ligands required for attachment to fibronectin-stimulated macrophages in the initial stages of nonopsonic phagocytosis.

Animals↗
PubMed1989

Assembly of mutant pilins in Pseudomonas aeruginosa: formation of pili composed of heterologous subunits.

Recently, we reported the degree of N-terminal processing within the cytoplasmic membranes of three mutant pilins from Pseudomonas aeruginosa PAK with respect to leader peptide removal and the methylation of the N-terminal phenylalanine (B. L. Pasloske and W. Paranchych, Mol. Microbiol. 2:489-495, 1988). The results of those experiments showed that the deletion of 4 or 8 amino acids within the highly conserved N terminus greatly inhibited leader peptide removal. On the other hand, the mutation of the glutamate at position 5 to a lysine permitted leader peptide cleavage but inhibited transmethylase activity. In this report, we have examined the effects of these mutant pilins upon pilus assembly in a P. aeruginosa PAO host with or without the chromosomally encoded pilin gene present. Pilins with deletions of 4 or 8 amino acids in the N-terminal region were not incorporated into pili. Interestingly, pilin subunits containing the glutamate-to-lysine mutation were incorporated into compound pili together with PAO wild-type subunits. However, the mutant pilins were unable to polymerize as a homopolymer. When wild-type PAK and PAO pilin subunits were expressed in the same bacterial strain, the pilin subunits assembled into homopolymeric pili containing one or the other type of subunit.

Bacterial Outer Membrane Proteins↗
PubMed1988

The expression of Pseudomonas aeruginosa PAK pilin gene mutants in Escherichia coli.

Previous work has demonstrated the expression of the cloned pilin gene of Pseudomonas aeruginosa PAK within Escherichia coli and has pinpointed this protein's localization exclusively to the cytoplasmic membrane (Finlay et al., 1986). To define regions of the pilin subunit necessary for its stability and transport within E. coli, we constructed six mutants of the pilin gene and studied their expression and localization using a T7 promoter system. Two of the mutants have either a 4- or 8-amino-acid deletion at the N-terminus and both were stably expressed and transported primarily to the cytoplasmic membrane of E. coli. The other four mutants are C-terminal truncations having between 36 and 56 amino acids of the N-terminal region of the unprocessed pilin. Studies with these truncated mutants revealed that only the first 36 residues of the unprocessed pilin subunit were required for insertion into the E. coli membrane.

Amino Acid Sequence↗
PubMed1988

The expression of mutant pilins in Pseudomonas aeruginosa: fifth position glutamate affects pilin methylation.

The expression within Pseudomonas aeruginosa PAO1 of three mutant pilin genes from P. aeruginosa PAK was studied to determine their effects on pilin stability, translocation into the membrane, leader peptide removal, and methylation of the mature N-terminal phenylalanine. The results revealed that a deletion of 4 or 8 amino acids within the immediate N-terminus of pilin had deleterious effects upon leader peptide cleavage. In addition, while the 4-amino-acid deletion did not affect pilin partitioning into the membrane, the 8-amino-acid deletion decreased the amount of pilin found within the membrane fraction. Of considerable interest was the finding that the mutation within the mature pilin of the glutamate at position 5 to a lysine did not prevent leader peptide removal but did inhibit the methylation of the N-terminal phenylalanine.

Amino Acid Sequence↗
PubMed1988

Serial isolates of Pseudomonas aeruginosa from a cystic fibrosis patient have identical pilin sequences.

Five isolates of Pseudomonas aeruginosa (CD2, CD3, CD4, CD5, and CD10) from a patient with cystic fibrosis were examined with regard to several genotypic and phenotypic characteristics to determine whether the patient was colonized with one or several distinct strains. Isolates CD2, CD3, and CD4 were obtained from a single sputum sample, and CD5 and CD10 were obtained 1 and 2 years later, respectively. On the basis of colonial morphology, serotyping, and antibiograms, the five isolates appeared to be different strains. However, Southern blot analysis with a 1.2-kilobase DNA probe containing the P. aeruginosa PAK pilin gene indicated that all five strains were identical at that genetic locus. The pilin genes of the five isolates were cloned and sequenced at the nucleotide level and found to be identical. Southern blot analysis with a probe from a separate region of the P. aeruginosa chromosome, a 741-base-pair PstI-NruI DNA fragment adjacent to the exotoxin A gene, also revealed genetic identity among these five clinical isolates. On this basis, it was concluded that this patient was colonized with a single strain of P. aeruginosa and that the strain had remained genetically stable over a period of 2 years. The predicted pilin sequence of the CD isolates was almost identical to that of strain PA103 (97% homology) and serologically related to PAO pilin, with which it shared 80% homology. No immunological cross-reactivity was detected between the CD and PAK pilins, which shared the least homology (62%) among the four pilins considered in this study. Although all five CD isolates contained identical pilin genes, three had acquired mutations which prevented normal expression of the pilus system. CD3 was a putative regulatory mutant which was unable to produce normal amounts of pilin, and CD4 and CD10 were putative assembly mutants which produced normal amounts of pilin but were unable to assemble the pilin subunit into intact pili.

Amino Acid Sequence↗
PubMed1986

Expression of the Pseudomonas aeruginosa PAK pilin gene in Escherichia coli.

Pseudomonas aeruginosa is a piliated opportunistic pathogen. We have recently reported the cloning of the structural gene for the pilus protein, pilin, from P. aeruginosa PAK (B. L. Pasloske, B. B. Finlay, and W. Paranchych, FEBS Lett. 183:408-412, 1985), and in this paper we present evidence that this chimera (pBP001) expresses P. aeruginosa PAK pilin in Escherichia coli independent of a vector promoter. The strength of the promoter for the PAK pilin gene was assayed, and the cellular location of the pilin protein within E. coli was examined. This protein was present mainly in the inner membrane fraction both with and without its six-amino-acid leader sequence, but it was not assembled into pili.

Bacterial Outer Membrane Proteins↗
PubMed1985

Cloning and sequencing of the Pseudomonas aeruginosa PAK pilin gene.

A 1.2-kilobase (kb) HindIII restriction fragment containing the pilin gene from Pseudomonas aeruginosa PAK has been cloned and sequenced. The pilin protein is 144 amino acids in length with a positively charged leader sequence of 6 amino acids. There is probably only one copy of the gene per chromosome.

Amino Acid Sequence↗
PubMed1985

Comparative studies of the amino acid and nucleotide sequences of pilin derived from Pseudomonas aeruginosa PAK and PAO.

The entire amino acid sequence for Pseudomonas aeruginosa PAO pilin was determined through peptide sequencing and from the complete nucleotide sequence encoding the pilin gene. The precursor PAO pilin is 149 amino acids in length which includes a 6-amino-acid positively charged leader sequence. Comparison of the amino acid sequences of pilin produced by P. aeruginosa PAO and PAK reveals a region of high homology corresponding to the leader peptide and residues 1 to 54 of the mature pilin. The amino acid sequence of the peptide encompassing the major antigenic determinant of PAK differs greatly from that of the equivalent region in PAO. The C-terminal regions of these proteins are semiconserved. Few major differences were found when the predicted secondary structures for PAO and PAK pilins were compared. Major nucleotide sequence variation between the equivalent restriction fragments from PAO and PAK occurred within the areas coding for the peptides containing the immunodominant site for PAK pilin and the C termini.

Amino Acid Sequence↗