<Emphasis Type="Italic">Burkholderia</Emphasis> Hep_Hag autotransporter (BuHA) proteins elicit a strong antibody response during experimental glanders but not human melioidosis

Background  

The bacterial biothreat agents Burkholderia mallei and Burkholderia pseudomallei are the cause of glanders and melioidosis, respectively. Genomic and epidemiological studies have shown that B. mallei is a recently emerged, host restricted clone of B. pseudomallei.     

Identification of a mutation in the structural alpha-L-fucosidase gene in fucosidosis.

Fucosidosis is an autosomal recessive lysosomal storage disorder characterized by progressive neurological deterioration and mental retardation. The disease results from deficient activity of alpha-L-fucosidase (E.C.3.2.1.51), a lysosomal enzyme that hydrolyzes fucose from fucoglycoconjugates. In an attempt to identify the mutation(s) that result(s) in fucosidosis, we performed Southern blot analysis of the structural gene encoding alpha-L-fucosidase (FUCA 1) in 23 patients affected with fucosidosis. In five patients Southern blot analysis showed obliteration of an EcoRI restriction site in the open reading frame of FUCA 1 encoding mature alpha-L-fucosidase. This abnormality was not observed in 80 controls, and it may be the basic defect responsible for fucosidosis in these patients. Both patients with the severe type I form of fucosidosis and patients with the less severe type II were shown to be homozygous for this presumed mutation. In the remaining 18 patients the EcoRI site obliteration, major-gene deletions, or insertions were not detected. This suggests that at least two different mutations are involved in fucosidosis. The heterogeneity found at the DNA level was not present at the protein level, as all fucosidosis patients investigated had low fucosidase protein (less than 6% of normal) and negligible fucosidase activity in fibroblasts and lymphoblastoid cell lines.     

Pip92: a short-lived, growth factor-inducible protein in BALB/c 3T3 and PC12 cells.

pip92 is a cellular immediate-early gene inducible by serum growth factors in fibroblasts. It is also induced in the rat pheochromocytoma cell line PC12 by agents that cause proliferation, neuronal differentiation, and membrane depolarization. We show that the pip92-encoded polypeptide is a proline-rich protein of 221 amino acids, has an extremely short half-life, and is localized in the cytoplasm. We hypothesize that Pip92 plays a role in mediating the cellular responses to a variety of extracellular signals.     

p-Aminobenzoate-p-aminobenzoate.

p-Aminobenzoate (PABA) synthase from Bacillus subtilis is an aggregate composed of two nonidentical subunits and has the following properties. (i) In crude extracts this enzyme catalyzes the formation of PABA in the presence of chorismate and either glutamine (amidotransferase) or ammonia (aminase). The amidotransferase activity is about 5- to 10-fold higher than the aminase activity and is stable for at least 1 week when frozen at -70 C. (II) Although no divalent cation requirement could be demonstrated with crude extracts, 2 mM ethylene-diaminetetraacetic acid completely inhibits both activities. (iii) After ammonium sulfate fractionation both the aminase and amidotransferase activities require Mg2+ and guanosine in addition to the substrates indicated above for optimal activity. The guanosine requirement can be replaced by guanosine 5'-monophosphate, guanosine 5'-diphosphate, and guanosine 5'-triphosphate but not by guanine, adenosine 5'-triphosphate, uridine 5'-triphosphate, cytidine 5'-triphosphate, thymidine 5'-triphosphate, inorganic phosphate, and phosphoribosylpyrophosphate. Furthermore, at a pH above 7.4 or below 6.4 activity is rapidly lost a 4 C, or -60 C. (IV) The enzyme is composed of two non-identical subunits, designated subunit A and subunit X. Subunit A has an estimated molecular weight of 31,000, whereas subunit X has an estimated molecular weight of 19,000. Subunit A has aminase activity but no amidotransferase activity; a mutation at the pabA locus results in the loss of PABA synthase activity. Subunit X, which is also a component of the anthranilate synthase complex, has no PABA synthase activity itself but complexes with subunit A to give an AX aggregate that can use glutamine as a substrate. (v) The molecular weight of the AX complex has been estimated at 50,000, suggesting a 1:1 ratio of subunits. (vi) The enzyme is readily associated and dissociated.     

Linkage of DNA markers to cystic fibrosis in 26 families.

Two DNA markers, the met oncogene and the anonymous probe, pJ3.11, previously reported to be tightly linked to cystic fibrosis (CF), were used for linkage analysis in 26 families with two or more individuals affected with CF. A new high frequency polymorphism was identified using BanI and the pmetD probe. The results of linkage analysis were as follows: between met and CF, lod score of 18.2 at theta of .009; between pJ3.11 and CF, lod score of 12.1 at theta of 0; and between met and pJ3.11, lod score of 16.7 at theta of 0. These data indicate that most or all of CF is due to an abnormality at a single locus and that the DNA markers are useful for prenatal diagnosis and heterozygote detection within affected families.     

Identification of human immunodeficiency virus envelope gene sequences influencing viral entry into CD4-positive HeLa cells, T-leukemia cells, and macrophages.

Infectious recombinant viruses were constructed from three molecularly cloned human immunodeficiency virus (HIV) strains varying in cell tropism. All recombinants showed a high infectivity titer on phytohemagglutinin-stimulated normal T lymphocytes. However, a 120-bp region of the envelope gene including the area of the V3 hypervariable loop was found to influence infectivity titer on both clone 1022 CD4-positive HeLa cells and CD4-positive CEM leukemia cells. Infectivity for macrophages was more complex. All viruses replicated in macrophages to a low level, but viral sequences both inside and outside the V3 loop region influenced the efficiency of replication. Two experiments showed that the mechanism of restriction of infection of 1022 cells by HIV strain JR-CSF was related to lack of virus entry. First, productive virus infection occurred after transfection of 1022 cells with viral plasmid DNA. Second, the nonpermissive HIV strain JR-CSF could infect 1022 cells when pseudotyped with the envelope of other retroviruses, including human T-cell leukemia virus type I (HTLV-I), HTLV-II, and amphotropic murine leukemia virus. These results demonstrate the possibility that unexpected cell types might be infected with HIV in human patients coinfected with HIV and HTLV-I or HTLV-II.