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B Rautenstrauss

Publications and source records attributed to B Rautenstrauss.

46 records · Page 3Linked to original sources
PubMed1996

Mosaicism for the Charcot-Marie-Tooth disease type 1A duplication suggests somatic reversion.

A female patient with clinical signs and symptoms of a demyelinating neuropathy was shown to have a duplication of the 1.5-Mb region on chromosome 17p11.2, typical of the great majority of cases of Charcot-Marie-Tooth disease type 1A (CMT1A). However, analysis of DNA extracted from peripheral blood revealed a 2:2.4 instead of the usual 2:3 ratio between the 7.8- and 6.0-kb EcoRI fragments in the proximal and distal repetitive extragenic palindromic (REP) elements of CMT1A. Detection of a 3.2-kb EcoRI/SacI kb junction fragment with probe pLR7.8 confirmed the CMT1A duplication. The dosage of this junction fragment, compared with a 2.8-kb EcoRI/SacI fragment of the proximal REP elements of CMT1A, was 2:0.58 instead of the expected 2:1 dosage for heterozygous CMT1A duplications. We hypothesized that the lower dosages of these restriction fragments specific for the CMT1A duplication were due to mosaicism; this was confirmed by fluorescence in situ hybridization analysis with the D17S122-specific probe pVAW409R1. In peripheral blood lymphocytes the percentage of interphase nuclei with a duplication in 17p11.2 was 49%. In interphase nuclei extracted from buccal mucosa, hair-root cells or paraffin-embedded nervous tissue the duplication was detectable in 51%, 66% and 74%, respectively. This is the first report of mosaicism in a patient with a CMT1A duplication identified by three different and independent techniques.

Adult↗
PubMed1995

Widespread expression of the peripheral myelin protein-22 gene (PMP22) in neural and non-neural tissues during murine development.

The gene encoding the peripheral myelin protein PMP22 is affected by various mutations in the hereditary peripheral neuropathies Charcot-Marie-Tooth disease type 1A (CMT1A), Déjérine-Sottas syndrome (DSS) and hereditary neuropathy with liability to pressure palsies (HNPP). In contrast to the recent remarkable progress in the genetics of the PMP22 gene, the biological function of PMP22 remains largely unknown. In this report, we have confirmed by using in situ hybridization techniques that high levels of PMP22 mRNA are present in maturing peripheral nerves of the 2-week-old mouse, a finding consistent with the PNS-specific defect observed in hereditary peripheral neuropathies. However, high levels of PMP22 transcripts were also found in the villi of the adult gut, and PMP22 expression was detected in various non-neural tissues during embryonic mouse development. In early embryogenesis (9.5 days postconception, dpc), PMP22 RNA expression appears restricted to the epithelial ectodermal layer. During early organogenesis (11.5 dpc), particularly high levels of expression are present in the capsule surrounding the liver and in the forming gut, while low levels of PMP22 mRNA can be found in precartilagous condensations forming the vertebrae and the ventricular layer of the myelencephalon. During midgestation development (14.5 dpc to 16.5 dpc), the number of PMP22-positive tissues increases, and high expression is detected in several mesoderm-derived tissues, in particular connective tissues of the face region, bones including the vertebrae, the lung mesenchym, and in muscles. In addition, high expression is also found in ectoderm-derived tissues, especially the epithelia of the lens and the skin. These findings strongly suggest that PMP22 serves not only a PNS-specific function but is also of broader biological significance in cell proliferation and/or differentiation.

Age Factors↗
PubMed1995

Substrate and product binding sites of yeast fatty acid synthase. Stoichiometry and binding kinetics of wild-type and in vitro mutated enzymes.

The four known substrate binding sites of yeast fatty acid synthase (FAS), Ser819 (acetyltransferase, OHAC) and Ser5421 (malonyl/palmitoyl transferase, OHMa1) of subunit beta and Ser180 (pantetheine binding site, SHc) and Cys1305 (3-oxoacyl synthase, SHp) of subunit alpha were replaced, by targeted in vitro mutagenesis, by the non-acylatable amino acids glutamine, glycine or alanine. The four mutated FAS proteins together with two pairs of double mutants (OHAc/OHMa1 and SHc/SHp) were episomally expressed in appropriate delta fas1 or delta fas2 deletion strains. The purified enzymes isolated from these transformants were used for comparative acyl binding studies with the substrates [1-14C]acetyl-CoA and [2-14C]malonyl-CoA. Malonate was found to be transacylated to enzyme-bound pantetheine (SHc) exclusively by the Ser5421 hydroxyl group of malonyltransferase (OHMa1) while acetate could use both the acetyl (Ser819) and the malonyl (Ser5421) transferase active sites on its way to the SHc and SHp binding sites. Acylation of SHc with either substrate was unaffected by the absence of the 'peripheral' SH group (SHp) while binding of acetate to SHp was dependent on enzyme-bound pantetheine (SHc). These genetic data support a revised model regarding the intra-molecular channeling of acetate and malonate within yeast fatty acid synthase. Quantitative acyl binding studies revealed a maximum of 2-3 mol rather than the expected 12 mol of malonate and of 6-7 mol rather than 24 mol of acetate bound/mol hexameric yeast FAS. Only 20-30% of the malonyl-enzyme and 35-50% of the acetyl enzyme represented performic-acid-labile thioester bonds. The binding characteristics of both substrates, exhibiting Hill coefficients distinctly lower than 1, as well as their non-linear Lineweaver-Burk and Scatchard plots, point to a marked negative cooperativity among the 12 yeast FAS subunits. The observed sub-stoichiometric substrate binding characteristics of the enzyme are ascribed to this effect. An a priori asymmetry of the complex appears unlikely since the coenzyme-A:FAS transacylation equilibrium may be shifted towards the fully acetylated enzyme in the presence of N-ethylmaleimide. In contrast to the limited acylation capacity of the 'resting' enzyme, complete acylation of yeast FAS at all of its 12 SHc and SHp sites is observed under steady-state conditions of fatty acid biosynthesis. Under these conditions, the enzyme exhibits full-site reactivity at its SHp, SHc and OHAc sites, but a concomitant 18-fold increase in Km of the coenzyme-A:OHAc transacylation reaction keeps the acyl-O-ester content of the acylated enzyme at less than 5% of the total.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1992

Differential proteolytic sensitivity of yeast fatty acid synthetase subunits alpha and beta contributing to a balanced ratio of both fatty acid synthetase components.

The Saccharomyces cerevisiae genes FAS1 and FAS2 encoding the beta and alpha subunit of yeast fatty acid synthetase (FAS), respectively, were individually deleted by one-step gene disruption. Northern blot analysis of RNA from the resulting fas null allele mutants indicated that deletion of FAS2 did not influence the transcription of FAS1, while FAS2 transcription was significantly reduced in the delta fas1 strain. These data suggest an activating role of subunit beta on FAS2 gene expression or, alternatively, a repression of FAS2 by an excess of its own gene product. Compared to the intact alpha 6 beta 6 complex, the individual FAS subunits synthesized in the delta fas1 or delta fas2 strains exhibit a considerably increased sensitivity towards the proteinases present in the yeast cell homogenate. Using yeast mutants specifically defective in the vacuolar proteinases yscA (PRA1/ PEP4 gene product) and/or yscB (PRB1 gene product), it was shown that in vitro, subunit alpha is efficiently degraded by proteinase yscA while for degradation of subunit beta, the combined action of proteinases yscA and yscB is necessary. In vivo, besides the vacuolar proteinases, an additional proteolytic activity specifically affecting free FAS subunit alpha becomes increasingly apparent in cells entering the stationary growth phase. In contrast, under similar conditions uncomplexed FAS subunit beta is stable in strains lacking the vacuolar proteinases yscA and yscB. The reduced FAS subunit levels, at the stationary phase, were independent of the corresponding FAS transcript concentrations. Thus, differential degradation pathways are obviously removing an excess of either FAS subunit, at least under starvation conditions. A combination of both regulation of FAS gene expression and proteolysis of free FAS polypeptides may therefore explain the equimolar amounts of both FAS subunits observed in yeast wild-type cells.

Blotting, Northern↗