scholarly journals Temperature Regulation of the Hemin Storage (Hms+) Phenotype of Yersinia pestis Is Posttranscriptional

2004 ◽  
Vol 186 (6) ◽  
pp. 1638-1647 ◽  
Author(s):  
Robert D. Perry ◽  
Alexander G. Bobrov ◽  
Olga Kirillina ◽  
Heather A. Jones ◽  
Lisa Pedersen ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Yersinia Pestis ◽  
Growth Temperature ◽  
Temperature Regulation ◽  
Iron Status ◽  
Outer Membrane Proteins ◽  
Western Blots ◽  
Protein Levels ◽  
The Stability ◽  
In Cells

ABSTRACT In Yersinia pestis, the Congo red (and hemin) binding that is characteristic of the Hms+ phenotype occurs at temperatures up to 34°C but not at higher temperatures. Manifestation of the Hms+ phenotype requires at least five proteins (HmsH, -F, -R, -S, and -T) that are organized into two separate operons: hmsHFRS and hmsT. HmsH and HmsF are outer membrane proteins, while HmsR, HmsS, and HmsT are predicted to be inner membrane proteins. We have used transcriptional reporter constructs, RNA dot blots, and Western blots to examine the expression of hms operons and proteins. Our studies indicate that transcription from the hmsHFRS and hmsT promoters is not regulated by the iron status of the cells, growth temperature, or any of the Hms proteins. In addition, the level of mRNA for both operons is not significantly affected by growth temperature. However, protein levels of HmsH, HmsR, and HmsT in cells grown at 37°C are very low compared to those in cells grown at 26°C, while the amounts of HmsF and HmsS show only a moderate reduction at the higher growth temperature. Neither the Pla protease nor a putative endopeptidase (Y2360) encoded upstream of hmsH is essential for temperature regulation of the Hms+ phenotype. However, HmsT at 37°C is sensitive to degradation by Lon and/or ClpPX. Thus, the stability of HmsH, HmsR, and HmsT proteins likely plays a role in temperature regulation of the Hms+ phenotype of Y. pestis.

scholarly journals DBC1 (Deleted in Breast Cancer 1) modulates the stability and function of the nuclear receptor Rev-erbα

2013 ◽  
Vol 451 (3) ◽  
pp. 453-461 ◽  
Author(s):  
Claudia C. S. Chini ◽  
Carlos Escande ◽  
Veronica Nin ◽  
Eduardo N. Chini
Keyword(s):  
Breast Cancer ◽  
Nuclear Receptor ◽  
Clock Genes ◽  
Mrna Levels ◽  
Protein Levels ◽  
The Stability ◽  
And Function ◽  
Interfering Rna ◽  
In Cells

The nuclear receptor Rev-erbα has been implicated as a major regulator of the circadian clock and integrates circadian rhythm and metabolism. Rev-erbα controls circadian oscillations of several clock genes and Rev-erbα protein degradation is important for maintenance of the circadian oscillations and also for adipocyte differentiation. Elucidating the mechanisms that regulate Rev-erbα stability is essential for our understanding of these processes. In the present paper, we report that the protein DBC1 (Deleted in Breast Cancer 1) is a novel regulator of Rev-erbα. Rev-erbα and DBC1 interact in cells and in vivo, and DBC1 modulates the Rev-erbα repressor function. Depletion of DBC1 by siRNA (small interfering RNA) in cells or in DBC1-KO (knockout) mice produced a marked decrease in Rev-erbα protein levels, but not in mRNA levels. In contrast, DBC1 overexpression significantly enhanced Rev-erbα protein stability by preventing its ubiquitination and degradation. The regulation of Rev-erbα protein levels and function by DBC1 depends on both the N-terminal and C-terminal domains of DBC1. More importantly, in cells depleted of DBC1, there was a dramatic decrease in circadian oscillations of both Rev-erbα and BMAL1. In summary, our data identify DBC1 as an important regulator of the circadian receptor Rev-erbα and proposes that Rev-erbα could be involved in mediating some of the physiological effects of DBC1.

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 Outer Membrane Proteins Ail and OmpF of Yersinia pestis Are Involved in the Adsorption of T7-Related Bacteriophage Yep-phi

2013 ◽  
Vol 87 (22) ◽  
pp. 12260-12269 ◽  
Author(s):  
X. Zhao ◽  
Y. Cui ◽  
Y. Yan ◽  
Z. Du ◽  
Y. Tan ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Yersinia Pestis ◽  
Outer Membrane ◽  
Outer Membrane Proteins

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 Synthetic hydrophobic peptides derived from MgtR weaken Salmonella pathogenicity and work with a different mode of action than endogenously produced peptides

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mariana Rosas Olvera ◽  
Preeti Garai ◽  
Grégoire Mongin ◽  
Eric Vivès ◽  
Laila Gannoun-Zaki ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Synthetic Peptides ◽  
Outer Membrane Proteins ◽  
Helical Structure ◽  
Inner Membrane ◽  
Protein Levels ◽  
Hydrophobic Peptides ◽  
Small Proteins ◽  
Exogenous Addition ◽  
Novel Therapeutic Strategies

Abstract Due to the antibiotic resistance crisis, novel therapeutic strategies need to be developed against bacterial pathogens. Hydrophobic bacterial peptides (small proteins under 50 amino acids) have emerged as regulatory molecules that can interact with bacterial membrane proteins to modulate their activity and/or stability. Among them, the Salmonella MgtR peptide promotes the degradation of MgtC, a virulence factor involved in Salmonella intramacrophage replication, thus providing the basis for an antivirulence strategy. We demonstrate here that endogenous overproduction of MgtR reduced Salmonella replication inside macrophages and lowered MgtC protein level, whereas a peptide variant of MgtR (MgtR-S17I), which does not interact with MgtC, had no effect. We then used synthetic peptides to evaluate their action upon exogenous addition. Unexpectedly, upon addition of synthetic peptides, both MgtR and its variant MgtR-S17I reduced Salmonella intramacrophage replication and lowered MgtC and MgtB protein levels, suggesting a different mechanism of action of exogenously added peptides versus endogenously produced peptides. The synthetic peptides did not act by reducing bacterial viability. We next tested their effect on various recombinant proteins produced in Escherichia coli and showed that the level of several inner membrane proteins was strongly reduced upon addition of both peptides, whereas cytoplasmic or outer membrane proteins remained unaffected. Moreover, the α-helical structure of synthetic MgtR is important for its biological activity, whereas helix-helix interacting motif is dispensable. Cumulatively, these results provide perspectives for new antivirulence strategies with the use of peptides that act by reducing the level of inner membrane proteins, including virulence factors.

scholarly journals Deciphering the Roles of Yersinia pestis Outer Membrane Proteins in their Native Environment

2021 ◽  
Vol 120 (3) ◽  
pp. 26a-27a
Author(s):  
James E. Kent ◽  
Lynn M. Fujimoto ◽  
Kyungsoo Shin ◽  
Chandan Singh ◽  
Yong Yao ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Yersinia Pestis ◽  
Outer Membrane ◽  
Outer Membrane Proteins

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.

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