scholarly journals The division defect of a Bacillus subtilis minD noc double mutant can be suppressed by Spx-dependent and Spx-independent mechanisms

2021 ◽  
Author(s):  
Yuanchen Yu ◽  
Felix Dempwolff ◽  
reid T oshiro ◽  
Frederico J Gueiros-Filho ◽  
Stephen C Jacobson ◽  
...  
Keyword(s):  
High Temperature ◽  
Double Mutant ◽  
Temperature Growth ◽  
Cytoskeletal Structure ◽  
Microfluidic Analysis ◽  
Z Ring ◽  
The Mind ◽  
Polar Division ◽  
Dependent Pathway ◽  
Suppressor Analysis

During growth, bacteria increase in size and divide.  Division is initiated by the formation of the Z-ring, an intense ring-like cytoskeletal structure formed by treadmilling protofilaments of the tubulin homolog FtsZ. FtsZ localization is thought to be controlled by the Min and Noc systems, and here, we explore why cell division fails at high temperature when the Min and Noc systems are simultaneously mutated. Microfluidic analysis of a minD noc double mutant indicated that FtsZ formed proto-Z-rings at periodic inter-chromosome locations but that the rings failed to mature and become functional. Extragenic suppressor analysis indicated that a variety of mutations restored high temperature growth to the minD noc double mutant, and while many were likely pleiotropic, others implicated the proteolysis of the transcription factor Spx. Further analysis indicated that a Spx-dependent pathway activated the expression of ZapA, a protein that primarily compensates for the absence of Noc. Additionally, an Spx-independent pathway increased the activity of the divisome to reduce the length of the cytokinetic period. Finally, we provide evidence of an as-yet-unidentified protein that is activated by Spx and governs the frequency of polar division and minicell formation.

scholarly journals The division defect of a Bacillus subtilis minD noc double mutant can be suppressed by Spx-dependent and Spx-independent mechanisms

2021 ◽  
Author(s):  
Yuanchen Yu ◽  
Felix Dempwolff ◽  
Reid T. Oshiro ◽  
Frederico J. Gueiros-Filho ◽  
Stephen C. Jacobson ◽  
...  
Keyword(s):  
Cell Division ◽  
High Temperature ◽  
Double Mutant ◽  
Temperature Growth ◽  
Division Site ◽  
Suppressor Mutations ◽  
Stress Response Pathway ◽  
Microfluidic Analysis ◽  
Z Ring ◽  
Polar Division

During growth, bacteria increase in size and divide. Division is initiated by the formation of the Z-ring, a ring-like cytoskeletal structure formed by treadmilling protofilaments of the tubulin homolog FtsZ. FtsZ localization is thought to be controlled by the Min and Noc systems, and here, we explore why cell division fails at high temperature when the Min and Noc systems are simultaneously mutated. Microfluidic analysis of a minD noc double mutant indicated that FtsZ formed proto-Z-rings at periodic inter-chromosome locations but that the rings failed to mature and become functional. Extragenic suppressor analysis indicated that a variety of mutations restored high temperature growth to the minD noc double mutant, and while many were likely pleiotropic, others implicated the proteolysis of the transcription factor Spx. Further analysis indicated that a Spx-dependent pathway activated the expression of ZapA, a protein that primarily compensates for the absence of Noc. Additionally, an Spx-independent pathway increased the activity of the divisome to reduce the length of the cytokinetic period. Finally, we provide evidence of an as-yet-unidentified protein that is activated by Spx and governs the frequency of polar division and minicell formation. IMPORTANCE Bacteria must properly position the location of the cell division machinery in order to grow, divide, and ensure each daughter cell receives one copy of the chromosome. In B. subtilis , cell division site selection depends on the Min and Noc systems, and while neither is individually essential, cells fail to grow at high temperature when both are mutated. Here, we show that cell division fails in the absence of Min and Noc, not due to a defect in FtsZ localization, but rather a failure in the maturation of the cell division machinery. Suppressor mutations that restored growth were selected and while some activated the expression of ZapA via the Spx stress response pathway, others appeared to directly enhance divisome activity.

scholarly journals Genetic analysis of temperature-sensitive lethal mutants of Salmonella typhimurium.

Genetics ◽  
1989 ◽  
Vol 123 (4) ◽  
pp. 625-633 ◽  
Author(s):  
M B Schmid ◽  
N Kapur ◽  
D R Isaacson ◽  
P Lindroos ◽  
C Sharpe
Keyword(s):  
High Temperature ◽  
Genetic Analysis ◽  
Salmonella Typhimurium ◽  
Complex Medium ◽  
Temperature Sensitive ◽  
Nonpermissive Temperature ◽  
Anaerobic Conditions ◽  
Temperature Growth ◽  
Lethal Phenotype ◽  
Lethal Mutations

Abstract We have isolated 440 mutants of Salmonella typhimurium that show temperature-sensitive growth on complex medium at 44 degrees. Approximately 16% of the mutations in these strains have been mapped to 17 chromosomal locations; two of these chromosomal locations seem to include several essential genes. Genetic analysis of the mutations suggests that the collection saturates the genes readily mutable to a ts lethal phenotype in S. typhimurium. Physiological characteristics of the ts lethal mutants were tested: 6% of the mutants can grow at high temperature under anaerobic conditions, 17% can grow when the medium includes 0.5 M KCl, and 9% of the mutants die after a 2-hr incubation at the nonpermissive temperature. Most ts lethal mutations in this collection probably affect genes required for growth at all temperatures (not merely during high temperature growth) since Tn10 insertions that cause a temperature-sensitive lethal phenotype are rare.

scholarly journals Dynamic nanocrystal response and high temperature growth of carbon nanotube–ferroelectric hybrid nanostructure

Nanoscale ◽  
2014 ◽  
Vol 6 (2) ◽  
pp. 1064-1070 ◽  
Author(s):  
Ashok Kumar ◽  
J. F. Scott ◽  
R. S. Katiyar
Keyword(s):  
High Temperature ◽  
Carbon Nanotube ◽  
Hybrid Nanostructure ◽  
Temperature Growth

MinD directly interacting with FtsZ at the H10 helix suggests a model for robust activation of MinC to destabilize FtsZ polymers

2017 ◽  
Vol 474 (18) ◽  
pp. 3189-3205 ◽  
Author(s):  
Ashoka Chary Taviti ◽  
Tushar Kant Beuria
Keyword(s):  
Cell Division ◽  
Single Point ◽  
Point Mutations ◽  
Direct Interaction ◽  
Ring Formation ◽  
Z Ring ◽  
Single Point Mutations ◽  
Biochemical Analyses ◽  
Ftsz Assembly ◽  
The Mind

Cell division in bacteria is a highly controlled and regulated process. FtsZ, a bacterial cytoskeletal protein, forms a ring-like structure known as the Z-ring and recruits more than a dozen other cell division proteins. The Min system oscillates between the poles and inhibits the Z-ring formation at the poles by perturbing FtsZ assembly. This leads to an increase in the FtsZ concentration at the mid-cell and helps in Z-ring positioning. MinC, the effector protein, interferes with Z-ring formation through two different mechanisms mediated by its two domains with the help of MinD. However, the mechanism by which MinD triggers MinC activity is not yet known. We showed that MinD directly interacts with FtsZ with an affinity stronger than the reported MinC–FtsZ interaction. We determined the MinD-binding site of FtsZ using computational, mutational and biochemical analyses. Our study showed that MinD binds to the H10 helix of FtsZ. Single-point mutations at the charged residues in the H10 helix resulted in a decrease in the FtsZ affinity towards MinD. Based on our findings, we propose a novel model for MinCD–FtsZ interaction, where MinD through its direct interaction with FtsZ would trigger MinC activity to inhibit FtsZ functions.

High temperature growth rate in MOCVD growth of AlGaAs

1984 ◽  
Vol 68 (1) ◽  
pp. 169-175 ◽  
Author(s):  
Tetsuo Soga ◽  
Yasuhito Takahashi ◽  
Shiro Sakai ◽  
Masayoshi Umeno
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Temperature Growth ◽  
Mocvd Growth

The Influence of Growth Temperature on Oxygen Concentration in GaN Buffer Layer

2008 ◽  
Vol 1068 ◽  
Author(s):  
Ewa Dumiszewska ◽  
Wlodek Strupinski ◽  
Piotr Caban ◽  
Marek Wesolowski ◽  
Dariusz Lenkiewicz ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Oxygen Concentration ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Temperature Growth ◽  
Gan Buffer Layer

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

High-temperature growth of thick AlN layers on sapphire (0001) substrates by solid source halide vapor-phase epitaxy

2008 ◽  
Vol 310 (17) ◽  
pp. 4016-4019 ◽  
Author(s):  
Ken-ichi Eriguchi ◽  
Takako Hiratsuka ◽  
Hisashi Murakami ◽  
Yoshinao Kumagai ◽  
Akinori Koukitu
Keyword(s):  
High Temperature ◽  
Vapor Phase ◽  
Vapor Phase Epitaxy ◽  
Temperature Growth

scholarly journals Calcium- and Calcineurin-Independent Roles for Calmodulin in Cryptococcus neoformans Morphogenesis and High-Temperature Growth

2005 ◽  
Vol 4 (6) ◽  
pp. 1079-1087 ◽  
Author(s):  
Peter R. Kraus ◽  
Connie B. Nichols ◽  
Joseph Heitman
Keyword(s):  
High Temperature ◽  
Cryptococcus Neoformans ◽  
Insertional Mutagenesis ◽  
Pathogenic Fungus ◽  
Critical Factor ◽  
Growth Defect ◽  
Insertion Mutant ◽  
Gene Encoding ◽  
Temperature Growth ◽  
New Genes

ABSTRACT The function of calcium as a signaling molecule is conserved in eukaryotes from fungi to humans. Previous studies have identified the calcium-activated phosphatase calcineurin as a critical factor in governing growth of the human pathogenic fungus Cryptococcus neoformans at mammalian body temperature. Here, we employed insertional mutagenesis to identify new genes required for growth at 37°C. One insertion mutant, cam1-ts, that displayed a growth defect at 37°C and hypersensitivity to the calcineurin inhibitor FK506 at 25°C was isolated. Both phenotypes were linked to the dominant marker in genetic crosses, and molecular analysis revealed that the insertion occurred in the 3′ untranslated region of the gene encoding the calcineurin activator calmodulin (CAM1) and impairs growth at 37°C by significantly reducing calmodulin mRNA abundance. The CAM1 gene was demonstrated to be essential using genetic analysis of a CAM1/cam1Δ diploid strain. In the absence of calcineurin function, the cam1-ts mutant displayed a severe morphological defect with impaired bud formation. Expression of a calmodulin-independent calcineurin mutant did not suppress the growth defect of the cam1-ts mutant at 37°C, indicating that calmodulin promotes growth at high temperature via calcineurin-dependent and -independent pathways. In addition, a Ca2+-binding-defective allele of CAM1 complemented the 37°C growth defect, FK506 hypersensitivity, and morphogenesis defect of the cam1-ts mutant. Our findings reveal that calmodulin performs Ca2+- and calcineurin-independent and -dependent roles in controlling C. neoformans morphogenesis and high-temperature growth.

High-temperature growth and spectroscopic characterization of Er,Yb:YAl3(BO3)4 epitaxial thin layers

2010 ◽  
Vol 32 (10) ◽  
pp. 1377-1379 ◽  
Author(s):  
N. Tolstik ◽  
S. Heinrich ◽  
A. Kahn ◽  
E. Volkova ◽  
V. Maltsev ◽  
...  
Keyword(s):  
High Temperature ◽  
Spectroscopic Characterization ◽  
Thin Layers ◽  
Temperature Growth
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