Novel Role of Phosphorylation-Dependent Interaction between FtsZ and FipA in Mycobacterial Cell Division

The bacterial divisome is a multiprotein complex. Specific protein-protein interactions specify whether cell division occurs optimally, or whether division is arrested. Little is known about these protein-protein interactions and their regulation in mycobacteria. We have investigated the interrelationship between the products of the Mycobacterium tuberculosis gene cluster Rv0014c-Rv0019c, namely PknA (encoded by Rv0014c) and FtsZ-interacting protein A, FipA (encoded by Rv0019c) and the products of the division cell wall (dcw) cluster, namely FtsZ and FtsQ. M. smegmatis strains depleted in components of the two gene clusters have been complemented with orthologs of the respective genes of M. tuberculosis. Here we identify FipA as an interacting partner of FtsZ and FtsQ and establish that PknA-dependent phosphorylation of FipA on T77 and FtsZ on T343 is required for cell division under oxidative stress. A fipA knockout strain of M. smegmatis is less capable of withstanding oxidative stress than the wild type and showed elongation of cells due to a defect in septum formation. Localization of FtsQ, FtsZ and FipA at mid-cell was also compromised. Growth and survival defects under oxidative stress could be functionally complemented by fipA of M. tuberculosis but not its T77A mutant. Merodiploid strains of M. smegmatis expressing the FtsZ(T343A) showed inhibition of FtsZ-FipA interaction and Z ring formation under oxidative stress. Knockdown of FipA led to elongation of M. tuberculosis cells grown in macrophages and reduced intramacrophage growth. These data reveal a novel role of phosphorylation-dependent protein-protein interactions involving FipA, in the sustenance of mycobacterial cell division under oxidative stress

Characterization and exploration of an As(III)-oxidizing bacterium TMKU1 for plant growth promotion under arsenic stress

Arsenic (As) pollution has been recognized as a serious global environmental problem. Though various remediation strategies are being explored to cope up with the As-toxicity, currently microbe-assisted detoxification of As is found to be the most promising technique for restoring As-contaminated rhizosphere soil for its eco-friendly nature. As(III)-oxidizing bacteria were reported to most suitable in this regard. In this study, an As(III)-oxidizing bacterium, TMKU1 was isolated from As-contaminated rhizospheric soil that could withstand up to 20 mM As(III) and 95 mM As(V). The strain was closely related to the genus Acinetobacter, according to 16 S rDNA analysis. The strain could transform ∼70% of As(III) to As(V) under aerobic culture condition. The transformation of As(III) was found to be catalyzed by arsenite oxidase, which is constitutive nature in this strain. The As(III)-oxidase was found to be encoded by the functional gene aioA harbored on the genomic DNA. The enzyme was localized mostly in the periplasm, and the partially purified enzyme showed the Km = 95.76667 μM and Vmax = 0.356341 M min−1g−1 protein. The novelty of this strain is that it could express plant growth promoting features like phosphate solubilization, siderophore production, IAA production and N2-fixation, both under stress-free and As-stress conditions. Seed bacterization with TMKU1 not only significantly increased the germination of chickpea seeds, but also shielded the seedlings from the As toxicity and accumulation. Overall, the results suggest that this bacterial candidate would be of potential use in agricultural practices for detoxification of As in crop field

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

CdO Nanoparticle Toxicity on Growth, Morphology, and Cell Division in Escherichia coli

This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli. Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, <i>ftsZ</i> and <i>ftsQ</i>, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli

Characterization of As(III)-oxidizing bacteria <i>Acinetobacter</i> sp. TMKU7 having plant growth promoting features for possible application in arsenic-contaminated crop field

Arsenic pollution is considered as one of the global environmental threats. Arsenic is found in nature mostly in two different valence states, namely arsenite [As(III)] and arsenate [As(V)], the former is more toxic due to its solubility and reactivity. Certain microbial communities inhabiting in the As-rich environment contribute a lot in the geochemical cycling of As. This study focuses on the isolation and identification of As(III) oxidizing bacteria from soil sample, and furthermore assessment of its As(III) transforming potential. The study was also aimed to hunt its plant growth promoting features for possible application to promote crop yield As-contaminated soil. Among the 28 bacterial isolates, a strain designated as TMKU7 could transform ∼80% As(III) to As(V) under culture condition. Based on morphological, biochemical, and molecular characterization, the strain was identified as Acinetobacter sp. Arsenite oxidase, the key player for As(III) to As(V) conversion was found to be constitutive in this strain, and the enzymatic activity was mostly found in the periplasmic fraction. The Km and Vmax of the partially purified As(III) oxidase were determined to be 41.43 μM and 0.19 μM min−1 μg−1 protein, respectively. The presence of As(III) oxidase gene (aioA) in the genomic DNA was further confirmed by PCR amplification. Agarose entrapped partially purified enzyme showed a potential for As(III) removal from water as well. The expression of various plant growth promoting traits have added additional importance to this As-resistant strain, which could be utilized as a prospective As-detoxification candidate in the As-contaminated crop field for sustainable agriculture.</p