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Articles 1 - 14 of 14

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Direct Visualization Of Hiv-1 Replication Intermediates Shows That Capsid And Cpsf6 Modulate Hiv-1 Intra-Nuclear Invasion And Integration, Christopher R. Chin, Jill Perreira, George Savidis, Jocelyn M. Portmann, Aaron M. Aker, Eric M. Feeley, Miles C. Smith, Abraham L. Brass Nov 2015

Direct Visualization Of Hiv-1 Replication Intermediates Shows That Capsid And Cpsf6 Modulate Hiv-1 Intra-Nuclear Invasion And Integration, Christopher R. Chin, Jill Perreira, George Savidis, Jocelyn M. Portmann, Aaron M. Aker, Eric M. Feeley, Miles C. Smith, Abraham L. Brass

Microbiology and Physiological Systems Publications and Presentations

Direct visualization of HIV-1 replication would improve our understanding of the viral life cycle. We adapted established technology and reagents to develop an imaging approach, ViewHIV, which allows evaluation of early HIV-1 replication intermediates, from reverse transcription to integration. These methods permit the simultaneous evaluation of both the capsid protein (CA) and viral DNA genome (vDNA) components of HIV-1 in both the cytosol and nuclei of single cells. ViewHIV is relatively rapid, uses readily available reagents in combination with standard confocal microscopy, and can be done with virtually any HIV-1 strain and permissive cell lines or primary cells. Using ViewHIV ...


Transmembrane Protein Insertion Orientation In Yeast Depends On The Charge Difference Across Transmembrane Segments, Their Total Hydrophobicity, And Its Distribution, Carol A. Harley, Jonathan A. Holt, Rhiannon Turner, Donald J. Tipper Sep 1998

Transmembrane Protein Insertion Orientation In Yeast Depends On The Charge Difference Across Transmembrane Segments, Their Total Hydrophobicity, And Its Distribution, Carol A. Harley, Jonathan A. Holt, Rhiannon Turner, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

The determinants of transmembrane protein insertion orientation at the endoplasmic reticulum have been investigated in Saccharomyces cerevisiae using variants of a Type III (naturally exofacial N terminus (Nexo)) transmembrane fusion protein derived from the N terminus of Ste2p, the alpha-factor receptor. Small positive and negative charges adjacent to the transmembrane segment had equal and opposite effects on orientation, and this effect was independent of N- or C-terminal location, consistent with a purely electrostatic interaction with response mechanisms. A 3:1 bias toward Nexo insertion, observed in the absence of a charge difference, was shown to reflect the Nexo bias conferred ...


Double-Stranded Ribonucleic Acid Killer Systems In Yeasts, Donald J. Tipper, Kieth A. Bostian Jun 1984

Double-Stranded Ribonucleic Acid Killer Systems In Yeasts, Donald J. Tipper, Kieth A. Bostian

Microbiology and Physiological Systems Publications and Presentations

Killer yeasts secrete polypeptide toxins which kill sensitive cells of their own species and frequently those of other species and genera of yeast. In this review we will focus on the molecular biology of the most intensively investigated killer system, the M1- dsRNA-determined Kl killer system of S. cerevisiae. We hope to demonstrate the relevance of this system to many of the vital issues in yeast and general eucaryotic molecular biology.


Secretion Of Saccharomyces Cerevisiae Killer Toxin: Processing Of The Glycosylated Precursor, H. Bussey, D. Saville, D. Greene, Donald J. Tipper, Keith A. Bostian Aug 1983

Secretion Of Saccharomyces Cerevisiae Killer Toxin: Processing Of The Glycosylated Precursor, H. Bussey, D. Saville, D. Greene, Donald J. Tipper, Keith A. Bostian

Microbiology and Physiological Systems Publications and Presentations

Killer toxin secretion was blocked at the restrictive temperature in Saccharomyces cerevisiae sec mutants with conditional defects in the S. cerevisiae secretory pathway leading to accumulation of endoplasmic reticulum (sec18), Golgi (sec7), or secretory vesicles (sec1). A 43,000-molecular-weight (43K) glycosylated protoxin was found by pulse-labeling in all sec mutants at the restrictive temperature. In sec18 the protoxin was stable after a chase; but in sec7 and sec1 the protoxin was unstable, and in sec1 11K toxin was detected in cell lysates. The chymotrypsin inhibitor tosyl-l-phenylalanyl chloromethyl ketone (TPCK) blocked toxin secretion in vivo in wild-type cells by inhibiting protoxin ...


Coat Protein Synthesis During Sporulation Of Bacillus Subtilis: Immunological Detection Of Soluble Precursors To The 12,200-Dalton Spore Coat Protein, Robert C. Goldman, Donald J. Tipper Sep 1981

Coat Protein Synthesis During Sporulation Of Bacillus Subtilis: Immunological Detection Of Soluble Precursors To The 12,200-Dalton Spore Coat Protein, Robert C. Goldman, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Antibody specific to the 12,200-dalton spore coat protein of Bacillus subtilis was used to detect the synthesis of cross-reacting material during sporulation. Cross-reacting protein was first detected by immunoprecipitation after 4 h of development and represented at least 1 to 2% of the total soluble protein synthesis at 5.5 h. A polypeptide of 21,000 daltons was detected in immunoprecipitates by gel electrophoresis. This polypeptide did not accumulate in sporulating cells and was rapidly turned over at the time of coat deposition. In contrast, a 32,000-dalton polypeptide reacted with antibody when unlabeled cell protein was denatured with ...


Comparison Of Various Properties Of Low-Molecular-Weight Proteins From Dormant Spores Of Several Bacillus Species, Katherine Yuan, W. Charles Johnson, Donald J. Tipper, Peter Setlow Jun 1981

Comparison Of Various Properties Of Low-Molecular-Weight Proteins From Dormant Spores Of Several Bacillus Species, Katherine Yuan, W. Charles Johnson, Donald J. Tipper, Peter Setlow

Microbiology and Physiological Systems Publications and Presentations

Several properties of the major proteins degraded during germination of spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis have been compared. All of the proteins had low molecular weights (6,000 to 13,000) and lacked cysteine, cystine, and tryptophan. The proteins could be subdivided into two groups: group I (B. megaterium A and C proteins, B. cereus A protein, and B. subtilis alpha and beta proteins) and group II (B. cereus and B. megaterium B proteins and B. subtilis gamma protein). Species in group II had lower levels of (or lacked) the amino acids isoleucine, leucine, methionine, and ...


Acid-Soluble Spore Proteins Of Bacillus Subtilis, W. C. Johnson, Donald J. Tipper Jun 1981

Acid-Soluble Spore Proteins Of Bacillus Subtilis, W. C. Johnson, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Acid-soluble spore proteins (ASSPs) comprise about 5% of the total protein of mature spores of different Bacillus subtilis strains. They consist of three abundant species, alpha, beta, and gamma, four less abundant species, and several minor species, alpha, beta, and gamma make up about 18, 18 and 36%, respectively, of the total ASSPs of strain 168, have molecular weights of 5,900, 5,9000, and 11,000, respectively, and resemble the major (A, C, and B) components of Bacillus megaterium ASSPs in several respects, including sensitivity to a specific B. megaterium spore endopeptidase. However, they have pI's of 6 ...


Encapsidation Of Yeast Killer Double-Stranded Ribonucleic Acids: Dependence Of M On L, Keith A. Bostian, Joyce A. Sturgeon, Donald J. Tipper Jul 1980

Encapsidation Of Yeast Killer Double-Stranded Ribonucleic Acids: Dependence Of M On L, Keith A. Bostian, Joyce A. Sturgeon, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Virus-like particles containing either L or M double-stranded ribonucleic acid (dsRNA) were isolated from a killer toxin-producing strains of Saccharomyces cerevisiae (K+ R+). At least 95% of M- and 87% of L-dsRNA were recovered in virus-like particle-containing fractions. The major capsid polypeptides (ScV-P1) of both L and M virus-like particles were shown to be identical, and 95% of the cellular ScV-P1 was found in the virus-like particle-containing fractions. Since L-dsRNA encodes ScV-P1, provision of this protein for encapsidation of M-dsRNA defines at least one functional relationship between these dsRNA genomes and associates the L-dsRNA with the killer character. If encapsidation ...


Morphology And Patterns Of Protein Synthesis During Sporulation Of Bacillus Subtilis Eryr Spo(Ts) Mutants, Robert C. Goldman, Donald J. Tipper May 1979

Morphology And Patterns Of Protein Synthesis During Sporulation Of Bacillus Subtilis Eryr Spo(Ts) Mutants, Robert C. Goldman, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Erythromycin-resistant (Eryr) mutants of Bacillus subtilis 168 fail to sporulate at high temperature (47 degrees C) but sporulate normally at 30 to 35 degrees C. They also fail to sporulate at any temperature in the presence of 2.5 micrograms of erythromycin per ml. Neither of these nonpermissive conditions appears to affect vegetative growth, and the periods of sensitivity to both conditions extend from 40 to 90% of the sporulation period. At 47 degrees C, net incorporation of methionine and phenylalanine in postexponential Eryr and 168 cells was similar, and fractionation of the labeled products by polyacrylamide gel electrophoresis gave ...


Location Of Peptidoglycan Lytic Enzymes In Bacillus Sphaericus, M. Guinand, M. J. Vacheron, G. Michel, Donald J. Tipper Apr 1979

Location Of Peptidoglycan Lytic Enzymes In Bacillus Sphaericus, M. Guinand, M. J. Vacheron, G. Michel, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

The level of three peptidoglycan hydrolases was determined in the mother cell compartment and forespores of Bacillus sphaericus. Vegetative and sporulating cells contained in LD-carboxypeptidase active only on the vegetative cell wall peptidoglycan, and we have previously shown that sporulation is accompanied by the production of two new enzymes active only on the spore cortex peptidoglycan. These gamma-D-glutamyl-meso-diaminopimelate endopeptidase and a meso-diaminopimelate-D-alanine dipeptidase. The LD-carboxypeptidase activity appeared to be located in the membranes of both the mother cells and forespores. Endopeptidase activity was located in the integument fraction of the forespores, and the dipeptidase activity was only found in the ...


Morphology Of An Escherichia Coli Mutant With A Temperature-Dependent Round Cell Shape, Makoto Iwaya, Robert Goldman, Donald J. Tipper, B. Feingold, Jack L. Strominger Dec 1978

Morphology Of An Escherichia Coli Mutant With A Temperature-Dependent Round Cell Shape, Makoto Iwaya, Robert Goldman, Donald J. Tipper, B. Feingold, Jack L. Strominger

Microbiology and Physiological Systems Publications and Presentations

Mutants of Escherichia coli capable of growing in the presence of 10 microgram of mecillinam per ml were selected after intensive mutagenesis. Of these mutants, 1.4% formed normal, rod-shaped cells at 30 degrees C but grew as spherical cells at 42 degrees C. The phenotype of one of these rod(Ts) mutants was 88% cotransducible with lip (14.3 min), and all lip+ rod(Ts) transductants of a lip recipient had the following characteristics: (i) growth was relatively sensitive to mecillinam at 30 degrees C but relatively resistant to mecillinam at 42 degrees C; (ii) penicillin-binding protein 2 was ...


Bacillus Subtilis Spore Coats: Complexity And Purification Of A Unique Polypeptide Component, Robert C. Goldman, Donald J. Tipper Sep 1978

Bacillus Subtilis Spore Coats: Complexity And Purification Of A Unique Polypeptide Component, Robert C. Goldman, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Extensively washed, dormant spores of Bacillus subtilis were disrupted with glass beads in buffer at pH 7 in the presence of protease inhibitors. Approximately 31% of the total spore protein was soluble, and another 14% was removed from the insoluble fraction by hydrolysis with lysozyme and washing with 1 M KCl and 0.1% sodium dodecyl sulfate. The residual spore integuments comprised 55% of the total spore proteins and consisted of coats and residual membrane components. Treatment of integuments with sodium dodecyl sulfate and reducing agents at pH 10 solubilized 40% of the total spore protein. Seven low-molecular-weight polypeptide components ...


Translation Of The L-Species Dsrna Genome Of The Killer-Associated Virus-Like Particles Of Saccharomyces Cerevisiae, James E. Hopper, Keith A. Bostian, Lucy B. Rowe, Donald J. Tipper Dec 1977

Translation Of The L-Species Dsrna Genome Of The Killer-Associated Virus-Like Particles Of Saccharomyces Cerevisiae, James E. Hopper, Keith A. Bostian, Lucy B. Rowe, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Virus-like particles containing the L (P1)-species of double-stranded RNA (dsRNA) were isolated from Saccharomyces cerevisiae, and the translational activity of the virus-like particle-derived dsRNA was analyzed in the wheat germ cell-free system. Denaturation of the dsRNA immediately prior to in vitro translation resulted in the synthesis of one major and at least three minor polypeptides, whereas undenatured dsRNA, as expected, did not stimulate [35S]methionine incorporation into polypeptides, but actually slightly inhibited endogenous activity. The major in vitro translation product of the denatured L-dsRNA was shown to be identical with the major L-dsRNA containing virus-like particle capsid polypeptide on ...


A Polypeptide Bacteriophage Receptor: Modified Cell Wall Protein Subunits In Bacteriophage-Resistant Mutants Of Bacillus Sphaericus Strain P-1, Lawrence Howard, Donald J. Tipper Mar 1973

A Polypeptide Bacteriophage Receptor: Modified Cell Wall Protein Subunits In Bacteriophage-Resistant Mutants Of Bacillus Sphaericus Strain P-1, Lawrence Howard, Donald J. Tipper

Microbiology and Physiological Systems Publications and Presentations

Bacillus sphaericus strain P-1 has previously been shown to have a tetragonally arrayed (T layer) protein which forms the outer layer of the cell wall. The T layer was quantitatively extracted from whole cells by 6 M urea, and the T layer subunits were purified by electrophoresis of the extracts on acrylamide gels containing 0.1% sodium dodecyl sulfate or 6 M urea. Using ethylene diacrylate cross-linked gels, the T layer was found to make up 16% of the total cellular protein. A virulent bacteriophage which is inactivated by purified T layer was isolated from soil. Twenty-four phage-resistant mutants were ...