The stability of outer-membrane protein and antigen profiles of a strain of Bacteroides intermedius grown in continuous culture at different pH and growth rates

1991 ◽  
Vol 37 (5) ◽  
pp. 368-376 ◽  
Author(s):  
G. H. Bowden ◽  
N. Nolette ◽  
A. S. McKee ◽  
I. R. Hamilton
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Growth Rates ◽  
Chemostat Culture ◽  
Outer Membrane Proteins ◽  
High Growth ◽  
Novel Proteins ◽  
Membrane Antigens ◽  
The Stability ◽  
Genotype Ii

The stability of the outer-membrane proteins and antigens of a strain of Bacteroides intermedius (VP1 8944 group genotype II) grown in contious culture at varying pH and growth rates (D = 0.025–0.2 h−1, pH 6.0–7.3) has been measured. The membranes showed nine major proteins (> 67–19.55 kilodaltons) and six major antigens (65–28 kilodaltons). Membrane proteins and antigens were stable under the conditions tested; the major proteins were detected in all membranes, and the antigen profiles tested with different antisera showed maximum similarities of 82–95%. Differences did occur in the amounts of membrane proteins synthesized; cells at high growth rates and those growing on the surfaces in the chemostat showed increased amounts of two proteins (40 and 32 kilodaltons) and possibly novel proteins of 24 and 25 kilodaltons. In addition, these membranes reflected increased synthesis or a change to increased reactivity of antigens between 20.5 and 24 kilodaltons. The results indicate stability of the expression of outer-membrane proteins and antigens in environments of differing pH and under different growth rates. However, the amount of these molecules synthesized can vary, and increases in certain proteins and antigens occur as the growth rate increases and the organisms grow on surfaces. Key words: Bacteroides intermedius, outer-membrane antigens, antigenic stability, chemostat culture, outer-membrane profiles.

scholarly journals Role of Phosphatidylethanolamine in the Biogenesis of Mitochondrial Outer Membrane Proteins

2013 ◽  
Vol 288 (23) ◽  
pp. 16451-16459 ◽  
Author(s):  
Thomas Becker ◽  
Susanne E. Horvath ◽  
Lena Böttinger ◽  
Natalia Gebert ◽  
Günther Daum ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Proper Function ◽  
Mitochondrial Outer Membrane ◽  
Tom Complex ◽  
Precursor Proteins ◽  
Helical Proteins ◽  
The Stability

The mitochondrial outer membrane contains proteinaceous machineries for the import and assembly of proteins, including TOM (translocase of the outer membrane) and SAM (sorting and assembly machinery). It has been shown that the dimeric phospholipid cardiolipin is required for the stability of TOM and SAM complexes and thus for the efficient import and assembly of β-barrel proteins and some α-helical proteins of the outer membrane. Here, we report that mitochondria deficient in phosphatidylethanolamine (PE), the second non-bilayer-forming phospholipid, are impaired in the biogenesis of β-barrel proteins, but not of α-helical outer membrane proteins. The stability of TOM and SAM complexes is not disturbed by the lack of PE. By dissecting the import steps of β-barrel proteins, we show that an early import stage involving translocation through the TOM complex is affected. In PE-depleted mitochondria, the TOM complex binds precursor proteins with reduced efficiency. We conclude that PE is required for the proper function of the TOM complex.

scholarly journals Mutations in genes encoding the mitochondrial outer membrane proteins Tom70 and Mdm10 of Podospora anserina modify the spectrum of mitochondrial DNA rearrangements associated with cellular death.

1997 ◽  
Vol 17 (11) ◽  
pp. 6359-6366 ◽  
Author(s):  
C Jamet-Vierny ◽  
V Contamine ◽  
J Boulay ◽  
D Zickler ◽  
M Picard
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Podospora Anserina ◽  
Mitochondrial Outer Membrane ◽  
Phenotypic Properties ◽  
Giant Mitochondria ◽  
Genes Encoding ◽  
Obligate Aerobe ◽  
The Stability

Tom70 and Mdm10 are mitochondrial outer membrane proteins. Tom70 is implicated in the import of proteins from the cytosol into the mitochondria in Saccharomyces cerevisiae and Neurospora crassa. Mdm10 is involved in the morphology and distribution of mitochondria in S. cerevisiae. Here we report on the characterization of the genes encoding these proteins in the filamentous fungus Podospora anserina. The two genes were previously genetically identified through a systematic search for nuclear suppressors of a degenerative process displayed by the AS1-4 mutant. The PaTom70 protein shows 80% identity with its N. crassa homolog. The PaMdm10 protein displays 35.9% identity with its S. cerevisiae homolog, and cytological analyses show that the PaMDM10-1 mutant exhibits giant mitochondria, as does the S. cerevisiae mdm10-1 mutant. Mutations in PaTOM70 and PaMDM10 result in the accumulation of specific deleted mitochondrial genomes during the senescence process of the fungus. The phenotypic properties of the single- and double-mutant strains suggest a functional relationship between the Tom70 and Mdm10 proteins. These data emphasize the role of the mitochondrial outer membrane in the stability of the mitochondrial genome in an obligate aerobe, probably through the import process.

scholarly journals Two novel proteins in the mitochondrial outer membrane mediate β-barrel protein assembly

2004 ◽  
Vol 166 (5) ◽  
pp. 621-627 ◽  
Author(s):  
Daigo Ishikawa ◽  
Hayashi Yamamoto ◽  
Yasushi Tamura ◽  
Kaori Moritoh ◽  
Toshiya Endo
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Protein Translocation ◽  
Outer Membrane Proteins ◽  
Protein Assembly ◽  
Mitochondrial Outer Membrane ◽  
Complex Assembly ◽  
Novel Proteins ◽  
Assembly Pathways

Mitochondrial outer and inner membranes contain translocators that achieve protein translocation across and/or insertion into the membranes. Recent evidence has shown that mitochondrial β-barrel protein assembly in the outer membrane requires specific translocator proteins in addition to the components of the general translocator complex in the outer membrane, the TOM40 complex. Here we report two novel mitochondrial outer membrane proteins in yeast, Tom13 and Tom38/Sam35, that mediate assembly of mitochondrial β-barrel proteins, Tom40, and/or porin in the outer membrane. Depletion of Tom13 or Tom38/Sam35 affects assembly pathways of the β-barrel proteins differently, suggesting that they mediate different steps of the complex assembly processes of β-barrel proteins in the outer membrane.

Antigenic variability of the outer membrane antigens of Legionella pneumophila serogroups 1 to 8

1987 ◽  
Vol 33 (7) ◽  
pp. 607-613 ◽  
Author(s):  
Maurice Boissinot ◽  
Danielle Ramsay ◽  
Christine Barthe ◽  
Jean R. Joly
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Legionella Pneumophila ◽  
Outer Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Strong Association ◽  
Sodium Dodecyl ◽  
Antigenic Determinants ◽  
Live Bacteria ◽  
Membrane Antigens

The outer membrane proteins of Legionella pneumophila serogroups 1 to 8 were prepared from broken cells by selective solubilization using sodium lauryl sarcosinate. The isolated proteins were separated by sodium dodecyl sulfate – polyacrylamide gel electrophoresis and transferred to nitrocellulose sheets. Rabbit antisera against each of the eight serogroups of L. pneumophila were obtained by immunizing each animal with live bacteria. The transferred proteins were revealed using these antisera and peroxidase-labeled swine anti-rabbit immunoglobulins. Antigenic determinants common to all eight serogroups were found in at least three outer membrane antigens (19, 29, and 45 kilodaltons (kDa)). However, cross-absorption experiments revealed that these three antigens were immunologically related, but not identical among serogroups. The antigenic relationships observed with two of these three antigens correlated well with cross-reactions observed in immunofluorescence. When a monoclonal antibody directed against L. pneumophila serogroup 1 lipopolysaccharide was used to reveal a blot of serogroup 1 outer membrane antigens, the 29- and 45-kDa bands appeared. This demonstrates a strong association between lipopolysaccharide and outer membrane proteins.

scholarly journals The Conservation of Low Complexity Regions in Bacterial Proteins Depends on the Pathogenicity of the Strain and Subcellular Location of the Protein

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 451
Author(s):  
Pablo Mier ◽  
Miguel A. Andrade-Navarro
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Bacterial Species ◽  
Outer Membrane Proteins ◽  
Subcellular Location ◽  
Low Complexity ◽  
Extracellular Proteins ◽  
Bacterial Strains ◽  
Bacterial Proteins ◽  
Protein Subcellular Location

Low complexity regions (LCRs) in proteins are characterized by amino acid frequencies that differ from the average. These regions evolve faster and tend to be less conserved between homologs than globular domains. They are not common in bacteria, as compared to their prevalence in eukaryotes. Studying their conservation could help provide hypotheses about their function. To obtain the appropriate evolutionary focus for this rapidly evolving feature, here we study the conservation of LCRs in bacterial strains and compare their high variability to the closeness of the strains. For this, we selected 20 taxonomically diverse bacterial species and obtained the completely sequenced proteomes of two strains per species. We calculated all orthologous pairs for each of the 20 strain pairs. Per orthologous pair, we computed the conservation of two types of LCRs: compositionally biased regions (CBRs) and homorepeats (polyX). Our results show that, in bacteria, Q-rich CBRs are the most conserved, while A-rich CBRs and polyA are the most variable. LCRs have generally higher conservation when comparing pathogenic strains. However, this result depends on protein subcellular location: LCRs accumulate in extracellular and outer membrane proteins, with conservation increased in the extracellular proteins of pathogens, and decreased for polyX in the outer membrane proteins of pathogens. We conclude that these dependencies support the functional importance of LCRs in host–pathogen interactions.

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