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E Beutler

Publications and source records attributed to E Beutler.

At least 235 records · Page 13Linked to original sources
PubMed1990

Red cell enzyme defects.

Erythrocytes are a readily available cell type that has proved to be extraordinarily useful in the diagnosis of enzyme abnormalities, both of genetic and nutritional origin. The metabolism of red cells is reviewed briefly, particularly with respect to the consequences of abnormalities in different types of enzymes. Erythrocyte enzyme abnormalities are classified into three broad, somewhat overlapping groups: (1) those that lead to abnormalities of red cell functions; (2) those that are reflected in the red cells but whose clinical consequences are primarily manifested in other tissues; and (3) those that have no known clinical consequences. Genetic variability of red cell enzymes is discussed, and advances in understanding red cell enzyme defects at the DNA level are highlighted.

Biological Transport, Active↗
PubMed1990

Molecular biology of G 6 PD variants.

Glucose-6-phosphate dehydrogenase (G6PD, E.C. 1.1.1.49) deficiency is probably the most common disease-producing enzyme deficiency of man. Originally described in the 1950's in Black Americans and regarded a single disorder, it soon became apparent that this enzyme defect occurred in many populations and that it was biochemically heterogeneous. By 1965 a considerable number of distinct variants had been described and a WHO Scientific Group was convened to standardize methods of characterization of variants, so as to allow meaningful interlaboratory comparisons to be made. In the succeeding quarter of a century nearly 400 variants believed to be unique have been characterized, most of them by the standard methods that had been adopted in 1967. Helpful as standardization proved to be, however, comparison of variants with one another proved to be difficult. Electrophoretic mobilities and kinetic constants vary with changes in reagents over which investigators have no control, and the lack of stability of enzymes and their kinetic characteristics makes side-by-side comparison a goal that can be achieved only rarely. It is not surprising, then, that in at least one instance variants that appeared to be quite different proved to have been obtained from two members of the same family, and were undoubtedly identical. It has thus been clear for many years that a true appreciation of the extent of G6PD mutations would require the acquisition of incontrovertible structural data.(ABSTRACT TRUNCATED AT 250 WORDS)

Africa↗
PubMed1990

Molecular genetics of the glucose-6-phosphate dehydrogenase (G6PD) Mediterranean variant and description of a new G6PD mutant, G6PD Andalus1361A.

Glucose-6-phosphate dehydrogenase (G6PD; E.C.1.1.1.49) deficiency is the most common human enzymopathy; more than 300 different biochemical variants of the enzyme have been described. In many parts of the world the Mediterranean type of G6PD deficiency is prevalent. However, G6PD Mediterranean has come to be regarded as a generic term applied to similar G6PD mutations thought, however, to represent a somewhat heterogeneous group. A C----T mutation at nucleotide 563 of G6PD Mediterranean has been identified by Vulliamy et al., and the same mutation has been found by De Vita et al. in G6PD Mediterranean, G6PD Sassari, and G6PD Cagliari. The latter subjects had an additional mutation, at nucleotide 1311, that did not produce a coding change. We have examined genomic DNA of five patients--four of Spanish origin and one of Jewish origin--having enzymatically documented G6PD Mediterranean. All had both the mutation at nucleotide 563 and that at nucleotide 1311. A sixth sample, resembling G6PD Mediterranean kinetically but with a slightly rapid electrophoretic mobility, was designated G6PD Andalus and was found to have a different mutation, a G----A transition at nucleotide 1361, producing an arginine-to-histidine substitution. These studies suggest that G6PD Mediterranean is, after all, relatively homogeneous.

Base Sequence↗
PubMed1989

Molecular heterogeneity of glucose-6-phosphate dehydrogenase A-.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is probably the most common disease-producing genetic polymorphism of humans. Virtually all G6PD-deficient Africans show the G6PD A- phenotype, an electrophoretically rapid, deficient enzyme. The recently acquired ability to identify the point mutations producing the different variants has given us new insights into the population genetics of G6PD variants. Twenty-nine males with the G6PD A- phenotype were studied. They were of African, Mexican, Spanish, and US white ethnic origin. All had the A---G transition at nucleotide 376 characteristic of G6PD A. In each case, one of three additional mutations was present, at nucleotides 202, 680, or 968. That in this population second mutations producing G6PD deficiency occurred only on the genetic background of G6PD A suggests that G6PD A was at one time the most common type of G6PD in Africa. However, the nucleotide sequence of the chimpanzee (Pan troglodytes) G6PD indicates that the primordial human type of G6PD was G6PD B.

Base Sequence↗
PubMed1989

Prediction of severity of Gaucher's disease by identification of mutations at DNA level.

The polymerase chain reaction was used to detect four mutations in the DNA of 47 unrelated patients with type I Gaucher's disease (94 Gaucher's disease alleles). Two of the mutations, 1226 and 1448, and a new mutation (XOVR) representing cross-over between the glucocerebrosidase gene and its closely linked pseudogene, were found. There were five genotypes--namely, 1226/1226, 1226/1448, 1226/XOVR, 1226/?, and ?/? (where "?" indicates that none of the four known mutations was present). Severity of the disease was assessed with a scoring index according to age at diagnosis and extent of organ involvement. Mutation 1226 was associated with a mild clinical phenotype, and mutation 1448 with a more severe phenotype. Mutation 1226 is the most common cause of Gaucher's disease in Jewish patients.

Adolescent↗
PubMed1989

Decay of hexokinase during reticulocyte maturation: is oxidative damage a signal for destruction?

Proteolysis of hexokinase in cell-free systems prepared from rabbit reticulocytes has been shown previously to be ATP-dependent and apparently mediated by the ubiquitin system (Magnani et al. J. Biol.Chem.261, 8327-8333). We have investigated this phenomenon, but found no substantial loss of hexokinase in cell-free systems prepared from fresh lysates. Storage of lysates at -20 degrees C or addition of a free radical generating system was required to demonstrate rapid ATP-dependent decay. It appears that initial oxidative damage to hexokinase does not abolish its activity but allows it to be recognized by an ATP-dependent proteolytic system. The relevance of this mechanism to in vivo degradation of hexokinase is discussed.

Adenosine Triphosphate↗
PubMed1989

The human glucocerebrosidase gene and pseudogene: structure and evolution.

We report the sequence of the entire human gene encoding beta-glucocerebrosidase and that of the associated pseudogene. The gene contains 11 exons extending from base pair 355 to base pair 7232 in the overall sequence. The gene promoter contains TATA- and CAT-like boxes upstream of the major 5' end of the glucocerebrosidase RNA. The two TATA boxes lie between nucleotides (-23)-(-27) and (-33)-(-39) and the two possible CAT boxes reside between nucleotides (-90)-(-94) and (-96)-(-99) in relation to the major 5' end of the mRNA. The functionality of the promoter region was monitored by coupling it to the bacterial gene coding for chloramphenicol acetyltransferase (CAT) and assaying the expression of the enzyme in cells transfected with this vector. The glucocerebrosidase promoter not only directs synthesis of the bacterial enzyme but also exhibits the same pattern of tissue-specific expression as that of the endogenous gene. An apparently tightly linked pseudogene is approximately 96% homologous to the functional gene. However, introns 2, 4, 6, and 7 have large "deletions" consisting of Alu sequences 313, 626, 320, and 277 bp in length, respectively. It is entirely possible that the ancestral gene lacks these sequences and that they have been inserted into the introns of the functioning gene. There is also a 55-bp deletion from a part of exon 9 flanked by a short inverted repeat. The sequence data should facilitate development of methods for diagnosis of Gaucher disease at the molecular level.

Base Sequence↗
PubMed1989

Evolution of the genome and the genetic code: selection at the dinucleotide level by methylation and polyribonucleotide cleavage.

Noting the scarcity of CpG dinucleotide in total genomic DNA derived from higher organisms and the scarcity of TpA dinucleotide in total genomic DNA derived from most life forms, we examined the distribution of these dinucleotides in sequences derived from functionally distinct types of human DNA, including mitochondrial DNA, intergenic DNA, intron DNA, and DNA destined to be represented in the cytoplasm as mRNA, tRNA, or rRNA. While CpG frequency has fallen to its lowest levels in DNA that is transcriptionally silent, TpA is most stringently excluded in DNA destined to be expressed as mRNA in the cytosol. This observation suggests that the selective pressures leading to the removal of CpG and TpA operate at different levels. With respect to TpA, dinucleotide scarcity may reflect a requirement for mRNA stability and may indicate the action of UpA-selective ribonucleases. We propose that, by reason of its instability, UpA must have been very rare in primordial RNA. Therefore, tRNA with the anticodon for this dinucleotide may have failed to evolve, making UpA the primordial doublet "stop" codon. The modern triplet code has faithfully conserved this arrangement in the two universal stop codons, UAA and UAG.

Base Sequence↗
PubMed1989

Identification of the binding domain for NADP+ of human glucose-6-phosphate dehydrogenase by sequence analysis of mutants.

Human erythrocyte glucose-6-phosphate dehydrogenase is normally quite stable in the presence of 10 microM NADP+. Certain glucose-6-phosphate dehydrogenase variants lose virtually all their activity at this concentration of NADP+ but are reactivated by 200 microM NADP+. Such variants presumably have a defect in their NADP+-binding site. We analyzed the sequence of cDNA or genomic DNA from seven unrelated patients with hemolytic anemia due to the inheritance of variants that are reactivated by NADP+. Six patients had substitutions of one of three adjacent amino acids, and the seventh patient had another amino acid substitution 23 residues downstream. These amino acids are highly conserved, all being present in rat and all but one being found also in Drosophila. The anomalous electrophoretic behavior of some of the variants can be explained by their loss of ability to bind NADP+. We conclude that the region in which these mutations occur defines the binding domain for NADP+ and that binding NADP+ that has been designated as "structural" and as "catalytic" probably occurs at the same site.

Amino Acid Sequence↗
PubMed1989

Alternative splicing of human glucose-6-phosphate dehydrogenase messenger RNA in different tissues.

Different forms of glucose-6-phosphate dehydrogenase (G-6-PD) have been described in different tissues. Moreover, the directly determined amino acid sequence amino end of the red cell enzyme does not exactly match the sequence deduced from cDNA isolated from HeLa cells or lymphoblasts. We have therefore investigated the sequence of cDNA from sperm, granulocytes, reticulocytes, brain, placenta, liver, lymphoblastoid cells, and cultured fibroblasts. A novel human cDNA, which has extra 138 bases coding 46 amino acids, was isolated from a lymphoblastoid cell library. Sequencing of genomic DNA amplified by the polymerase chain reaction (PCR) revealed that the extra sequence was derived from the 3'-end of intron 7 by alternative splicing. This longer form of mRNA was also detected in sperm and granulocytes. Sequence analysis using PCR-amplified cDNA revealed that the 5'-end of the coding sequence of G6PD mRNA in reticulocytes is identical to those in other tissues.

Amino Acid Sequence↗
PubMed1989

The molecular biology of variation in glucose-6-phosphate dehydrogenase.

The complete cDNA sequence of G-6-PD is now known, and the application of modern technology has made it possible to rapidly accumulate sequence data regarding G-6-PD variants. The information that has become available demonstrates that there are several different types of G-6-PD A(-) but all have in common the mutation that is characteristic of G-6-PD A(+), viz. a substitution of G for A at nucleotide 376. Moreover, the same nucleotide substitutions have been found in Spanish and Italian subjects, indicating that the G-6-PD A(-) mutation is much more common in non-African populations than had been thought. G-6-PD Mediterranean, on the other hand, seems to be more uniform than had been thought previously. A wealth of information regarding structure/function relationship of enzymes is potentially available through the study of G-6-PD variants.

Amino Acid Sequence↗