scholarly journals AimB is a small protein regulator of cell size and MreB assembly

2019 ◽  
Author(s):  
John N. Werner ◽  
Handuo Shi ◽  
Jen Hsin ◽  
Kerwyn Casey Huang ◽  
Zemer Gitai ◽  
...  
Keyword(s):  
Unnatural Amino Acids ◽  
Cell Shape ◽  
Caulobacter Crescentus ◽  
Specific Activity ◽  
Interacting Proteins ◽  
Cell Width ◽  
Site Specific ◽  
Small Protein ◽  
Dynamics Simulations ◽  
Species Specific

AbstractThe MreB actin-like cytoskeleton assembles into dynamic polymers that coordinate cell shape in many bacteria. In contrast to most other cytoskeletons, few MreB interacting proteins have been well characterized. Here we identify a small protein fromCaulobacter crescentus, AimB, as anAssemblyInhibitor ofMreB. AimB overexpression mimics inhibition of MreB polymerization, leading to increased cell width and MreB delocalization. Molecular dynamics simulations suggest that AimB binds MreB at its monomer-monomer protofilament interaction cleft. We validate this model through functional analysis of point mutants in both AimB and MreB, photo-crosslinking studies with site-specific unnatural amino acids, and species-specific activity of AimB. Together, our findings indicate that AimB promotes MreB dynamics by inhibiting monomer-monomer assembly interactions, representing a new mechanism for regulating actin-like polymers and the first identification of a non-toxin MreB assembly inhibitor.

scholarly journals RodZ modulates geometric localization of the bacterial actin MreB to regulate cell shape

2017 ◽  
Author(s):  
Alexandre Colavin ◽  
Handuo Shi ◽  
Kerwyn Casey Huang
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Spatial Organization ◽  
Dependent Manner ◽  
Cell Width ◽  
E Coli ◽  
Wall Growth ◽  
The Rich ◽  
Dynamics Simulations ◽  
Geometric Localization

AbstractIn the rod-shaped bacteriumEscherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape across changing environments, although the molecular mechanism by which cell width is regulated remains unknown. Here, we demonstrate that the bitopic membrane protein RodZ regulates the biophysical properties of MreB and alters the spatial organization ofE. colicell-wall growth. The relative expression levels of MreB and RodZ changed in a manner commensurate with variations in growth rate and cell width. We carried out single-cell analyses to determine that RodZ systematically alters the curvature-based localization of MreB and cell width in a manner dependent on the concentration of RodZ. Finally, we identified MreB mutants that we predict using molecular dynamics simulations to alter the bending properties of MreB filaments at the molecular scale similar to RodZ binding, and showed that these mutants rescued rod-like shape in the absence of RodZ alone or in combination with wild-type MreB. Together, our results show thatE. colicontrols its shape and dimensions by differentially regulating RodZ and MreB to alter the patterning of cell-wall insertion, highlighting the rich regulatory landscape of cytoskeletal molecular biophysics.

Novel Toxin-antitoxin System Xn-mazEF from Xenorhabdus nematophi-la: Identification, Characterization and Functional Exploration

2020 ◽  
Vol 16 ◽  
Author(s):  
Jogendra Singh Nim ◽  
Mohit Yadav ◽  
Lalit Kumar Gautam ◽  
Chaitali Ghosh ◽  
Shakti Sahi ◽  
...  
Keyword(s):  
Interaction Analysis ◽  
Functional Characterization ◽  
Host Cells ◽  
System Control ◽  
Xenorhabdus Nematophila ◽  
Functional Features ◽  
Dynamics Simulations ◽  
Species Specific ◽  
Rna Interaction

Background: Xenorhabdus nematophila maintains species-specific mutual interaction with nematodes of Steinernema genus. Type II Toxin Antitoxin (TA) systems, the mazEF TA system controls stress and programmed cell death in bacteria. Objective: This study elucidates the functional characterization of Xn-mazEF, a mazEF homolog in X. nematophila by computational and in vitro approaches. Methods: 3 D- structural models for Xn-MazE toxin and Xn-MazF antitoxin were generated, validated and characterized for protein - RNA interaction analysis. Further biological and cellular functions of Xn-MazF toxin were also predicted. Molecular dynamics simulations of 50ns for Xn-MazF toxin complexed with nucleic acid units (DU, RU, RC, and RU) were performed. The MazF toxin and complete MazEF operon were endogenously expressed and monitored for the killing of Escherichia coli host cells under arabinose induced tightly regulated system. Results: Upon induction, E. coli expressing toxin showed rapid killing within four hours and attained up to 65% growth inhibition, while the expression of the entire operon did not show significant killing. The observation suggests that the Xn-mazEF TA system control transcriptional regulation in X. nematophila and helps to manage stress or cause toxicity leading to programmed death of cells. Conclusion: The study provides insights into structural and functional features of novel toxin, XnMazF and provides an initial inference on control of X. nematophila growth regulated by TA systems.

Site-specific mutagenesis with unnatural amino acids

1989 ◽  
Vol 14 (10) ◽  
pp. 400-403 ◽  
Author(s):  
Spencer J. Anthony-Cahill ◽  
Michael C. Griffith ◽  
Christopher J. Noren ◽  
Daniel J. Suich ◽  
Peter G. Schultz
Keyword(s):  
Amino Acids ◽  
Unnatural Amino Acids ◽  
Site Specific

Species-Specific Activity of Glycolipid Ligands for Invariant NKT Cells

ChemBioChem ◽  
2012 ◽  
Vol 13 (9) ◽  
pp. 1349-1356 ◽  
Author(s):  
Emma M. Dangerfield ◽  
Janice M. H. Cheng ◽  
Deborah A. Knight ◽  
Robert Weinkove ◽  
P. Rod Dunbar ◽  
...  
Keyword(s):  
Specific Activity ◽  
Nkt Cells ◽  
Invariant Nkt Cells ◽  
Species Specific

scholarly journals The small protein MbiA interacts with MreB and modulates cell shape inCaulobacter crescentus

2012 ◽  
Vol 85 (6) ◽  
pp. 1090-1104 ◽  
Author(s):  
Anastasiya A. Yakhnina ◽  
Zemer Gitai
Keyword(s):  
Cell Shape ◽  
Small Protein

scholarly journals FtsZ-Dependent Elongation of a Coccoid Bacterium

mBio ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
Ana R. Pereira ◽  
Jen Hsin ◽  
Ewa Król ◽  
Andreia C. Tavares ◽  
Pierre Flores ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Shape ◽  
Single Point ◽  
Spherical Shape ◽  
Single Point Mutation ◽  
Wild Type ◽  
Dead End ◽  
Dynamics Simulations

ABSTRACT A mechanistic understanding of the determination and maintenance of the simplest bacterial cell shape, a sphere, remains elusive compared with that of more complex shapes. Cocci seem to lack a dedicated elongation machinery, and a spherical shape has been considered an evolutionary dead-end morphology, as a transition from a spherical to a rod-like shape has never been observed in bacteria. Here we show that a Staphylococcus aureus mutant (M5) expressing the ftsZ G193D allele exhibits elongated cells. Molecular dynamics simulations and in vitro studies indicate that FtsZ G193D filaments are more twisted and shorter than wild-type filaments. In vivo , M5 cell wall deposition is initiated asymmetrically, only on one side of the cell, and progresses into a helical pattern rather than into a constricting ring as in wild-type cells. This helical pattern of wall insertion leads to elongation, as in rod-shaped cells. Thus, structural flexibility of FtsZ filaments can result in an FtsZ-dependent mechanism for generating elongated cells from cocci. IMPORTANCE The mechanisms by which bacteria generate and maintain even the simplest cell shape remain an elusive but fundamental question in microbiology. In the absence of examples of coccus-to-rod transitions, the spherical shape has been suggested to be an evolutionary dead end in morphogenesis. We describe the first observation of the generation of elongated cells from truly spherical cocci, occurring in a Staphylococcus aureus mutant containing a single point mutation in its genome, in the gene encoding the bacterial tubulin homologue FtsZ. We demonstrate that FtsZ-dependent cell elongation is possible, even in the absence of dedicated elongation machinery.

scholarly journals Species-Specific Activity of SIV Nef and HIV-1 Vpu in Overcoming Restriction by Tetherin/BST2

2009 ◽  
Vol 5 (5) ◽  
pp. e1000429 ◽  
Author(s):  
Bin Jia ◽  
Ruth Serra-Moreno ◽  
William Neidermyer ◽  
Andrew Rahmberg ◽  
John Mackey ◽  
...  
Keyword(s):  
Specific Activity ◽  
Species Specific ◽  
Hiv 1

Structure and Function Studies of GPCRs by Site-Specific Incorporation of Unnatural Amino Acids

2017 ◽  
pp. 195-215
Author(s):  
Meilin Tian ◽  
Qian Wang ◽  
Chonggang Yuan ◽  
Shixin Ye
Keyword(s):  
Amino Acids ◽  
Unnatural Amino Acids ◽  
Structure And Function ◽  
Site Specific ◽  
And Function
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