Search PubMed⌕ Search

Biomedical subjects

S L Bernstein

Publications and source records attributed to S L Bernstein.

7 recordsLinked to original sources
PubMed2001

Mutations of the protocadherin gene PCDH15 cause Usher syndrome type 1F.

Human chromosome 10q21-22 harbors USH1F in a region of conserved synteny to mouse chromosome 10. This region of mouse chromosome 10 contains Pcdh15, encoding a protocadherin gene that is mutated in ames waltzer and causes deafness and vestibular dysfunction. Here we report two mutations of protocadherin 15 (PCDH15) found in two families segregating Usher syndrome type 1F. A Northern blot probed with the PCDH15 cytoplasmic domain showed expression in the retina, consistent with its pathogenetic role in the retinitis pigmentosa associated with USH1F.

Aged↗
PubMed2000

Usher syndrome 1D and nonsyndromic autosomal recessive deafness DFNB12 are caused by allelic mutations of the novel cadherin-like gene CDH23.

Genes causing nonsyndromic autosomal recessive deafness (DFNB12) and deafness associated with retinitis pigmentosa and vestibular dysfunction (USH1D) were previously mapped to overlapping regions of chromosome 10q21-q22. Seven highly consanguineous families segregating nonsyndromic autosomal recessive deafness were analyzed to refine the DFNB12 locus. In a single family, a critical region was defined between D10S1694 and D10S1737, approximately 0.55 cM apart. Eighteen candidate genes in the region were sequenced. Mutations in a novel cadherin-like gene, CDH23, were found both in families with DFNB12 and in families with USH1D. Six missense mutations were found in five families with DFNB12, and two nonsense and two frameshift mutations were found in four families with USH1D. A northern blot analysis of CDH23 showed a 9.5-kb transcript expressed primarily in the retina. CDH23 is also expressed in the cochlea, as is demonstrated by polymerase chain reaction amplification from cochlear cDNA.

Alleles↗
PubMed1990

Biochemical purification and crystallographic characterization of the fiber-forming protein pilin from Neisseria gonorrhoeae.

Pilus fibers are long protein filaments on many pathogenic bacteria that participate in attachment to host cells. Although the self-assembling protein pilin is the major structural component of the Neisseria gonorrhoeae pilus fiber, several other proteins co-purified with pilin through the repeated solubilization-reassociation steps of the biochemical purification. Pilin solubilized in the nondenaturing detergent n-octyl-beta-D-glucopyranoside remained an aggregate of about 100 kDa at pH 9.5, but was reduced to a 40-kDa dimer at pH 10.5, suggesting that assembly involves electrostatic interactions of lysine, tyrosine, or other side chains with high pKa values. Pilin dimers and aggregates of higher molecular mass were partially stable even in the presence of sodium dodecyl sulfate and beta-mercaptoethanol. Removal of pilus-associated proteins and stabilization of pilin multimers permitted the reproducible crystallization of pilin. Three-dimensional needle- and plate-shaped crystals of purified N. gonorrhoeae pilin (strain MS11 variant C30) grew from 36 to 40% polyethylene glycol 400, pH 8.0-9.0, in space group C222, with cell dimensions a = 126.4, b = 121.2, c = 26.7 A and Vm = 2.84 A3/dalton for one molecule per asymmetric unit. The best crystals diffracted to 2.4 A resolution using synchrotron radiation, were stable to x-ray damage, and appear suitable for determination of the atomic structure. This approach of stabilizing and crystallizing an intermediate assembly state may be useful for other fiber-forming proteins, which have previously not been successfully crystallized in forms that diffract to atomic resolution.

Bacterial Outer Membrane Proteins↗
PubMed1987

Three dimensional structure of bacterial pili.

Crystallographic and associated biochemical and structural studies are in progress on the fiber-forming pilin proteins of the gonococcal pilus. Preparative scale purification procedures have been developed for the gonococcal pilin protein, which appear generally applicable to bacterial pilins. For three gonococcal pilin protein strains, we have obtained both reassembled pilus fibers and three-dimensional crystals. One needle-shaped crystal form of gonococcal C30 pilin diffracts beyond 3 A resolution using synchrotron x-ray radiation. A diffraction data set to 3.5 A resolution has been collected on these needle-shaped crystals (lattice spacings a = 125.4(3) b = 120.4(3), c = 26.61(4) A) in which the packing arrangement of the pilin subunits appears to resemble that seen in the pilus fibers using electron microscopy. X-ray diffraction data confirm our proposed model for the overall polypeptide fold of a pilin subunit, which is an antiparallel 4-alpha helix bundle similar to tobacco mosaic virus coat protein and myohemerythrin.

Bacterial Outer Membrane Proteins↗
PubMed1979

An improved method for the rapid isolation of brain ribonucleic acid.

An improved one-step method for the extraction of RNA from rat brain is described. Fresh or frozen tissue is disrupted in the powerful protein denaturant guanidine thiocyanate, and RNA isolated by ultracentrifugation through CsCl. The procedure is advantageous in that it is relatively simple, is rapid and does not expose the sample to enzyme treatments or repeated organic extractions.

Animals↗