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Metal Homeostasis and Resistance in Microbes

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Microbiology".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 11628

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Prof. Dr. Cheol-Won Yun

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Guest Editor

School of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea
Interests: metal biology; biotechnology; fungal genetics

Special Issue Information

Dear Colleagues,

Virtually all living organisms require essential trace metal elements, which are required to carry out diverse physiological functions in numerous living organisms including microorganisms. However, the acquisition and utilization of trace metals is strictly regulated because of their toxicity. Microorganisms live in diverse environments ranging from mild to harsh conditions, and their fast adaptation to harsh conditions is an advantage of microorganisms. Hence, microorganisms have developed various mechanisms to maintain cellular metal homeostasis under various conditions and to survive against to metal stresses. The regulatory mechanisms of metal homeostasis, as well as simultaneous stress responses and resistance mechanisms against metal toxicity, have been studied extensively in various microbial model systems. Furthermore, the interaction between different metals in microorganisms also has an important function in maintaining metal homeostasis. However, the detailed mechanisms of cellular metal homeostasis and resistance against metal toxicity at the molecular level remained unsolved. This Special Issue is aimed at identifying the exact mechanisms of metal homeostasis and mechanisms of resistance against metal toxicity in microorganisms at the molecular level.

Prof. Dr. Cheol-Won Yun
Guest Editor

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Keywords

iron
copper
zinc
manganese
nickel
pathogens
microorganism
homeostasis
resistance
toxicity

Published Papers (4 papers)

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Research

14 pages, 2311 KiB

Open AccessArticle

Characterization of Two Highly Arsenic-Resistant Caulobacteraceae Strains of Brevundimonas nasdae: Discovery of a New Arsenic Resistance Determinant

by Xiaojun Yang, Yuanping Li, Renwei Feng, Jian Chen, Hend A. Alwathnani, Weifeng Xu and Christopher Rensing

Int. J. Mol. Sci. 2022, 23(10), 5619; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23105619 - 17 May 2022

Cited by 6 | Viewed by 2049

Abstract

Arsenic (As), distributed widely in the natural environment, is a toxic substance which can severely impair the normal functions in living cells. Research on the genetic determinants conferring functions in arsenic resistance and metabolism is of great importance for remediating arsenic-contaminated environments. Many organisms, including bacteria, have developed various strategies to tolerate arsenic, by either detoxifying this harmful element or utilizing it for energy generation. More and more new arsenic resistance (ars) determinants have been identified to be conferring resistance to diverse arsenic compounds and encoded in ars operons. There is a hazard in mobilizing arsenic during gold-mining activities due to gold- and arsenic-bearing minerals coexisting. In this study, we isolated 8 gold enrichment strains from the Zijin gold and copper mine (Longyan, Fujian Province, China) wastewater treatment site soil, at an altitude of 192 m. We identified two Brevundimonas nasdae strains, Au-Bre29 and Au-Bre30, among these eight strains, having a high minimum inhibitory concentration (MIC) for As(III). These two strains contained the same ars operons but displayed differences regarding secretion of extra-polymeric substances (EPS) upon arsenite (As(III)) stress. B. nasdae Au-Bre29 contained one extra plasmid but without harboring any additional ars genes compared to B. nasdae Au-Bre30. We optimized the growth conditions for strains Au-Bre29 and Au-Bre30. Au-Bre30 was able to tolerate both a lower pH and slightly higher concentrations of NaCl. We also identified folE, a folate synthesis gene, in the ars operon of these two strains. In most organisms, folate synthesis begins with a FolE (GTP-Cyclohydrolase I)-type enzyme, and the corresponding gene is typically designated folE (in bacteria) or gch1 (in mammals). Heterologous expression of folE, cloned from B. nasdae Au-Bre30, in the arsenic-hypersensitive strain Escherichia coli AW3110, conferred resistance to As(III), arsenate (As(V)), trivalent roxarsone (Rox(III)), pentavalent roxarsone (Rox(V)), trivalent antimonite (Sb(III)), and pentavalent antimonate (Sb(V)), indicating that folate biosynthesis is a target of arsenite toxicity and increased production of folate confers increased resistance to oxyanions. Genes encoding Acr3 and ArsH were shown to confer resistance to As(III), Rox(III), Sb(III), and Sb(V), and ArsH also conferred resistance to As(V). Acr3 did not confer resistance to As(V) and Rox(V), while ArsH did not confer resistance to Rox(V). Full article

(This article belongs to the Special Issue Metal Homeostasis and Resistance in Microbes)

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25 pages, 5082 KiB

Open AccessArticle

Transcriptomics and Functional Analysis of Copper Stress Response in the Sulfate-Reducing Bacterium Desulfovibrio alaskensis G20

by Abhilash Kumar Tripathi, Priya Saxena, Payal Thakur, Shailabh Rauniyar, Dipayan Samanta, Vinoj Gopalakrishnan, Ram Nageena Singh and Rajesh Kumar Sani

Int. J. Mol. Sci. 2022, 23(3), 1396; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23031396 - 26 Jan 2022

Cited by 10 | Viewed by 3799

Abstract

Copper (Cu) is an essential micronutrient required as a co-factor in the catalytic center of many enzymes. However, excess Cu can generate pleiotropic effects in the microbial cell. In addition, leaching of Cu from pipelines results in elevated Cu concentration in the environment, which is of public health concern. Sulfate-reducing bacteria (SRB) have been demonstrated to grow in toxic levels of Cu. However, reports on Cu toxicity towards SRB have primarily focused on the degree of toxicity and subsequent elimination. Here, Cu(II) stress-related effects on a model SRB, Desulfovibrio alaskensis G20, is reported. Cu(II) stress effects were assessed as alterations in the transcriptome through RNA-Seq at varying Cu(II) concentrations (5 µM and 15 µM). In the pairwise comparison of control vs. 5 µM Cu(II), 61.43% of genes were downregulated, and 38.57% were upregulated. In control vs. 15 µM Cu(II), 49.51% of genes were downregulated, and 50.5% were upregulated. The results indicated that the expression of inorganic ion transporters and translation machinery was massively modulated. Moreover, changes in the expression of critical biological processes such as DNA transcription and signal transduction were observed at high Cu(II) concentrations. These results will help us better understand the Cu(II) stress-response mechanism and provide avenues for future research. Full article

(This article belongs to the Special Issue Metal Homeostasis and Resistance in Microbes)

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20 pages, 2064 KiB

Open AccessArticle

Cadmium Stress Reprograms ROS/RNS Homeostasis in Phytophthora infestans (Mont.) de Bary

by Joanna Gajewska, Nur Afifah Azzahra, Özgün Ali Bingöl, Karolina Izbiańska-Jankowska, Tomasz Jelonek, Joanna Deckert, Jolanta Floryszak-Wieczorek and Magdalena Arasimowicz-Jelonek

Int. J. Mol. Sci. 2020, 21(21), 8375; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21218375 - 08 Nov 2020

Cited by 8 | Viewed by 2852

Abstract

Heavy metal pollution causes many soils to become a toxic environment not only for plants, but also microorganisms; however, little is known how heavy metal contaminated environment affects metabolism of phytopathogens and their capability of infecting host plants. In this study the oomycete Phytophthora infestans (Mont.) de Bary, the most harmful pathogen of potato, growing under moderate cadmium stress (Cd, 5 mg/L) showed nitro-oxidative imbalance associated with an enhanced antioxidant response. Cadmium notably elevated the level of nitric oxide, superoxide and peroxynitrite that stimulated nitrative modifications within the RNA and DNA pools in the phytopathogen structures. In contrast, the protein pool undergoing nitration was diminished confirming that protein tyrosine nitration is a flexible element of the oomycete adaptive strategy to heavy metal stress. Finally, to verify whether Cd is able to modify P. infestans pathogenicity, a disease index and molecular assessment of disease progress were analysed indicating that Cd stress enhanced aggressiveness of vr P. infestans towards various potato cultivars. Taken together, Cd not only affected hyphal growth rate and caused biochemical changes in P. infestans structures, but accelerated the pathogenicity as well. The nitro-oxidative homeostasis imbalance underlies the phytopathogen adaptive strategy and survival in the heavy metal contaminated environment. Full article

(This article belongs to the Special Issue Metal Homeostasis and Resistance in Microbes)

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15 pages, 3268 KiB

Open AccessArticle

The Role of Zinc in Copper Homeostasis of Aspergillus fumigatus

by Suzie Kang, Hyewon Seo, Hee-Soo Moon, Joon-Ho Kwon, Yong-Sung Park and Cheol-Won Yun

Int. J. Mol. Sci. 2020, 21(20), 7665; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21207665 - 16 Oct 2020

Cited by 5 | Viewed by 2137

Abstract

Copper is an essential metal ion that performs many physiological functions in living organisms. Deletion of Afmac1, which is a copper-responsive transcriptional activator in A. fumigatus, results in a growth defect on aspergillus minimal medium (AMM). Interestingly, we found that zinc starvation suppressed the growth defect of the Δafmac1 strain on AMM. In addition, the growth defect of the Δafmac1 strain was recovered by copper supplementation or introduction of the CtrC gene into the Δafmac1 strain. However, chelation of copper by addition of BCS to AMM failed to recover the growth defect of the Δafmac1 strain. Through Northern blot analysis, we found that zinc starvation upregulated CtrC and CtrA2, which encode membrane copper transporters. Interestingly, we found that the conserved ZafA binding motif 5′-CAA(G)GGT-3′ was present in the upstream region of CtrC and CtrA2 and that mutation of the binding motif led to failure of ZafA binding to the upstream region of CtrC and upregulation of CtrC expression under zinc starvation. Furthermore, the binding activity of ZafA to the upstream region of CtrC was inversely proportional to the zinc concentration, and copper inhibited the binding of ZafA to the upstream region of CtrC under a low zinc concentration. Taken together, these results suggest that ZafA upregulates copper metabolism by binding to the ZafA binding motif in the CtrC promoter region under low zinc concentration, thus regulating copper homeostasis. Furthermore, we found that copper and zinc interact in cells to maintain metal homeostasis. Full article

(This article belongs to the Special Issue Metal Homeostasis and Resistance in Microbes)

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