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Tong W, Yang D, Qiu S, Tian S, Ye Z, Yang S, Yan L, Li W, Li N, Pei X, Sun Z, Liu C, Peng S, Li Y, Wang Q, Peng Z. Relevance of genetic causes and environmental adaptation of Cronobacter spp. isolated from infant and follow-up formula production factories and retailed products in China: A 7-year period of continuous surveillance based on genome-wide analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174368. [PMID: 38955273 DOI: 10.1016/j.scitotenv.2024.174368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 06/25/2024] [Accepted: 06/27/2024] [Indexed: 07/04/2024]
Abstract
The possible contamination routes, environmental adaptation, and genetic basis of Cronobacter spp. in infant and follow-up formula production factories and retailed products in mainland China have been determined by laboratory studies and whole-genome comparative analysis in a 7-year nationwide continuous surveillance spanning from 2012 to 2018. The 2-year continuous multicenter surveillance of the production process (conducted in 2013 and 2014) revealed that the source of Cronobacter spp. in the dry-blending process was the raw dry ingredients and manufacturing environment (particularly in the vibro sieve and vacuum cleaner), while in the combined process, the main contamination source was identified as the packing room. It is important to note that, according to the contamination control knowledge obtained from the production process surveillance, the contamination rate of retail powdered infant formula (PIF) and follow-up formula (FUF) products in China decreased significantly from 2016 onward, after improving the hygiene management practices in factories. The prevalence of Cronobacter spp. in retailed PIF and FUF in China in 2018 was dramatically reduced from 1.55 % (61/3925, in 2012) to an average as low as 0.17 % (13/7655 in 2018). Phenotype determination and genomic analysis were performed on a total of 90 Cronobacter spp. isolates obtained from the surveillance. Of the 90 isolates, only two showed resistance to either cefazolin or cefoxitin. The multilocus sequence typing results revealed that C. sakazakii sequence type 1 (ST1), ST37, and C. malonaticus ST7 were the dominant sequence types (STs) collected from the production factories, while C. sakazakii ST1, ST4, ST64, and ST8 were the main STs detected in the retailed PIF and FUF nationwide. One C. sakazakii ST4 isolate (1.1 %, 1/90) had strong biofilm-forming ability and 13 isolates (14.4 %, 13/90) had weak biofilm-forming ability. Genomic analysis revealed that Cronobacter spp. have a relatively stable core-genome and an increasing pan-genome size. Plasmid IncFIB (pCTU3) was prevalent in this genus and some contained 14 antibacterial biocide- and metal-resistance genes (BMRGs) including copper, silver, and arsenic resistant genes. Plasmid IncN_1 was predicted to contain 6 ARGs. This is the first time that a multi-drug resistance IncN_1 type plasmid has been reported in Cronobacter spp. Genomic variations with respect to BMRGs, virulence genes, antimicrobial resistance genes (ARGs), and genes involved in biofilm formation were observed among strains of this genus. There were apparent differences in copies of bcsG and flgJ between the biofilm-forming group and non-biofilm-forming group, indicating that these two genes play key roles in biofilm formation. The findings of this study have improved our understanding of the contamination characteristics and genetic basis of Cronobacter spp. in PIF and FUF and their production environment in China and provide important guidance to reduce contamination with this pathogen during the production of PIF and FUF.
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Affiliation(s)
- Wei Tong
- Jiangxi Provincial Key Laboratory of Diagnosis and Traceability of Foodborne Diseases, Jiangxi Provincial Center for Disease Control and Prevention, Nanchang City, Jiangxi Province, PR China
| | - Dajin Yang
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China
| | - Shaofu Qiu
- Chinese PLA Center for Disease Control and Prevention, Beijing City, PR China
| | - Sai Tian
- Chinese PLA Center for Disease Control and Prevention, Beijing City, PR China
| | - Zehong Ye
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China; School of Public Health, Shandong Second Medical University, Weifang City, Shandong Province, PR China
| | - Shuran Yang
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China
| | - Lin Yan
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China
| | - Weiwei Li
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China
| | - Ning Li
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China
| | - Xiaoyan Pei
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China
| | - Zhongqing Sun
- Qingdao Municipal Center for Disease Control and Prevention, Qingdao City, Shandong Province, PR China
| | - Chengwei Liu
- Jiangxi Provincial Key Laboratory of Diagnosis and Traceability of Foodborne Diseases, Jiangxi Provincial Center for Disease Control and Prevention, Nanchang City, Jiangxi Province, PR China
| | - Silu Peng
- Jiangxi Provincial Key Laboratory of Diagnosis and Traceability of Foodborne Diseases, Jiangxi Provincial Center for Disease Control and Prevention, Nanchang City, Jiangxi Province, PR China
| | - Ying Li
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China.
| | - Qi Wang
- Chinese PLA Center for Disease Control and Prevention, Beijing City, PR China.
| | - Zixin Peng
- NHC Key Laboratory of Food Safety Risk Assessment, Chinese Academy of Medical Science Research Unit (2019RU014), China National Center for Food Safety Risk Assessment, Beijing City, PR China; Department of Nutrition and Food Safety, Peking Union Medical College; Research Unit of Food Safety, Chinese Academy of Medical Sciences, PR China.
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Jin Y, Liu Y, Liu S, Wang E, Chen W. Convergent gene pair dSH3 and irr regulate Pi and Fe homeostasis in Bradyrhizobium diazoefficiens USDA110 and symbiotic nitrogen fixation efficiency. Microbiol Res 2024; 280:127571. [PMID: 38134513 DOI: 10.1016/j.micres.2023.127571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023]
Abstract
The nitrogen-fixing bacteroids inhabit inside legume root nodules must manage finely the utilization of P and Fe, the two most critical elements, due to their antagonistic interactions. While the balance mechanism for them remains unclear. A double SH3 domain-containing protein (dSH3) in the Bradyrhizobium diazoefficiens USDA110 was found to inhibit the alkaline phosphatase activity, thereby reducing P supply from organophosphates. The dSH3 gene is adjacent to the irr gene, which encodes the iron response repressor and regulates Fe homeostasis under Fe-limited conditions. Their transcription directions converge to a common intergenic sequence (IGS) region, forming a convergent transcription. Extending the IGS region through Tn5 transposon or pVO155 plasmid insertion significantly down-regulated expression of this gene pair, leading to a remarkable accumulation of P and an inability to grow under Fe-limited conditions. Inoculation of soybean with either of the insertion mutants resulted in N2-fixing failure. However, the IGS-deleted mutant showed no visible changes in N2-fixing efficiency on soybean compared to that inoculated with wild type. These findings reveal a novel regulative strategy in the IGS region and its flanking convergent gene pair for antagonistic utilization of P and Fe in rhizobia and coordination of N2-fixing efficiency.
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Affiliation(s)
- Yuhao Jin
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, PR China
| | - Yuanhui Liu
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, PR China
| | - Sheng Liu
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, PR China
| | - Entao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
| | - Wenfeng Chen
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, PR China.
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Baek S, Lee EJ. PhoU: a multifaceted regulator in microbial signaling and homeostasis. Curr Opin Microbiol 2024; 77:102401. [PMID: 37988810 DOI: 10.1016/j.mib.2023.102401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/18/2023] [Accepted: 10/24/2023] [Indexed: 11/23/2023]
Abstract
Inorganic phosphate (Pi) is a fundamental molecule crucial for numerous biological processes, such as ATP synthesis and phospholipid formation. To prevent cellular toxicity, Pi transport is often linked to counterion transport within the bacterium. This review discusses the multifaceted functions of the PhoU protein in bacterial regulation, focusing on its role in coordinating Pi transport with counterions, controlling polyphosphate accumulation, and regulating secondary metabolite biosynthesis and DNA repair. We also explore recent findings that challenge the conventional view of PhoU simply as a negative regulator in phosphate signaling, suggesting its broader impact on bacterial physiology and stress response. Understanding the diverse functions of PhoU provides new insight into bacterial biology and offers potential therapeutic implications.
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Affiliation(s)
- Seungwoo Baek
- Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, South Korea
| | - Eun-Jin Lee
- Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, South Korea.
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Li J, Liu H, Liu Z, Zhang X, Blake RE, Huang Z, Cai M, Wang F, Yu C. Transformation mechanism of methylphosphonate to methane by Burkholderia sp: Insight from multi-labeled water isotope probing and transcriptomic. ENVIRONMENTAL RESEARCH 2023; 218:114970. [PMID: 36470350 DOI: 10.1016/j.envres.2022.114970] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/25/2022] [Accepted: 11/27/2022] [Indexed: 06/17/2023]
Abstract
Methylphosphonate (MPn), has been identified as a likely source of methane in aerobic ocean and may be responsible for the "ocean methane paradox", that is oversaturation of dissolved methane in oxic sea waters. However, the mechanism underlying the cleavage of C-P bonds during microbial degradation is not well understood. Using multi-labeled water isotope probing (MLWIP) and transcriptome analysis, we investigated the phosphate oxygen isotope systematics and mechanisms of microbial-mediated degradation of MPn in this study. In the aerobic culture containing MPn as the only phosphorus source, there was a significant release of inorganic phosphate (149.4 μmol/L) and free methane (268.3 mg/L). The oxygen isotopic composition of inorganic phosphorus (δ18OP) of accumulated released phosphate was 4.50‰, 23.96‰, and 40.88‰, respectively, in the corresponding 18O-labeled waters of -10.3‰, 9.9‰, and 30.6‰, and the slope obtained in plots of δ18OP versus the oxygen isotopic composition of water (δ18OW) was 0.89. Consequently, 89% of the oxygen atoms (Os) in phosphate (PO4) were exchanged with 18O-labeled waters in the medium, while the rest were exchanged with intracellular metabolic water. It has been confirmed that the C-P bond cleavage of MPn occurs in the cell with both ambient and metabolic water participation. Moreover, phn gene clusters play significant roles to cleave the C-P bond of MPn for Burkholderia sp. HQL1813, in which phnJ, phnM and phnI genes are significantly up-regulated during MPn decomposition to methane. In conclusion, the aerobic biotransformation of MPn to free methane by Burkholderia sp. HQL1813 has been elucidated, providing new insights into the mechanism that bio-cleaves C-P bonds to produce methane aerobically in aqueous environments for representative phosphonates.
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Affiliation(s)
- Junhong Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China
| | - Houquan Liu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China
| | - Zeqin Liu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China
| | - Xianhua Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China
| | - Ruth Elaine Blake
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, 06520-8109, USA
| | - Zhiyong Huang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, National Technology Innovation Center of Synthetic Biology, 300308, Tianjin, China
| | - Minmin Cai
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, National Engineering Research Centre of Microbial Pesticides, Huazhong Agricultural University, 430070, Wuhan, China
| | - Fei Wang
- School of Environment, Beijing Normal University, 19 Xinjiekouwai, Haidian District, 100875, Beijing, China.
| | - Chan Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China.
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Li J, Yu C, Liu Z, Wang Y, Wang F. Microplastic accelerate the phosphorus-related metabolism of bacteria to promote the decomposition of methylphosphonate to methane. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:160020. [PMID: 36356736 DOI: 10.1016/j.scitotenv.2022.160020] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/08/2022] [Accepted: 11/03/2022] [Indexed: 06/16/2023]
Abstract
Microplastic (MP) contaminants in marine water have become a global public health concern because of their persistence and potentially adverse effects on organisms. MP can affect the growth and metabolism of marine microorganisms and further impact the microbial environmental functions. The molecular impact mechanisms of MP on specific functional microbes with the capability of decomposing methylphosphonate (MPn) to release methane (CH4) in oxygenated water have rarely been reported upon. Herein, we investigated the effects of MP on microbes and concomitant methanogenesis via the microbial degradation of MPn. Furthermore, the specific perturbation was revealed at the molecular level combined with transcriptomics and metabolomics. The results showed that intracellular phosphorus utilization by MPn-degrading strain Burkholderia sp. HQL1813 was enhanced by accelerating the catabolism of MPn. Phosphorus transport-related genes (phnG-M, pstSCAB, phnCDE) were upregulated in the MP exposure groups. Amino acid metabolism, the phosphotransferase system and nucleotide metabolism were also perturbed after MP exposure. Notably, released CH4 increased by 24 %, 29 % and 14 % in the exposure group. In addition, the responses of the strain were dose-independent with increasing MP doses. These findings are beneficial for clarifying the effect of MP on specific functional microbes at the molecular level and their degradation of CH4 by MPn.
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Affiliation(s)
- Junhong Li
- School of Energy & Environmental Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, 100083 Beijing, China; School of Environment, Beijing Normal University, 19 Xinjiekouwai Street, 100875 Beijing, China
| | - Chan Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062 Wuhan, China
| | - Zeqin Liu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062 Wuhan, China
| | - Yan Wang
- School of Energy & Environmental Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, 100083 Beijing, China
| | - Fei Wang
- School of Environment, Beijing Normal University, 19 Xinjiekouwai Street, 100875 Beijing, China.
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Coordination of Phosphate and Magnesium Metabolism in Bacteria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1362:135-150. [PMID: 35288878 DOI: 10.1007/978-3-030-91623-7_12] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The majority of cellular phosphate (PO4-3; Pi) exists as nucleoside triphosphates, mainly adenosine triphosphate (ATP), and ribosomal RNA (rRNA). ATP and rRNA are also the largest cytoplasmic reservoirs of magnesium (Mg2+), the most abundant divalent cation in living cells. The co-occurrence of these ionic species in the cytoplasm is not coincidental. Decades of work in the Pi and Mg2+ starvation responses of two model enteric bacteria, Escherichia coli and Salmonella enterica, have led to the realization that the metabolisms of Pi and Mg2+ are interconnected. Bacteria must acquire these nutrients in a coordinated manner to achieve balanced growth and avoid loss of viability. In this chapter, we will review how bacteria sense and respond to fluctuations in environmental and intracellular Pi and Mg2+ levels. We will also discuss how these two compounds are functionally linked, and how cells elicit physiological responses to maintain their homeostasis.
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Genome-Driven Discovery of Enzymes with Industrial Implications from the Genus Aneurinibacillus. Microorganisms 2021; 9:microorganisms9030499. [PMID: 33652876 PMCID: PMC7996765 DOI: 10.3390/microorganisms9030499] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/19/2021] [Accepted: 02/23/2021] [Indexed: 01/27/2023] Open
Abstract
Bacteria belonging to the genus Aneurinibacillus within the family Paenibacillaceae are Gram-positive, endospore-forming, and rod-shaped bacteria inhabiting diverse environments. Currently, there are eight validly described species of Aneurinibacillus; however, several unclassified species have also been reported. Aneurinibacillus spp. have shown the potential for producing secondary metabolites (SMs) and demonstrated diverse types of enzyme activities. These features make them promising candidates with industrial implications. At present, genomes of 9 unique species from the genus Aneurinibacillus are available, which can be utilized to decipher invaluable information on their biosynthetic potential as well as enzyme activities. In this work, we performed the comparative genome analyses of nine Aneurinibacillus species representing the first such comprehensive study of this genus at the genome level. We focused on discovering the biosynthetic, biodegradation, and heavy metal resistance potential of this under-investigated genus. The results indicate that the genomes of Aneurinibacillus contain SM-producing regions with diverse bioactivities, including antimicrobial and antiviral activities. Several carbohydrate-active enzymes (CAZymes) and genes involved in heavy metal resistance were also identified. Additionally, a broad range of enzyme classes were also identified in the Aneurinibacillus pan-genomes, making this group of bacteria potential candidates for future investigations with industrial applications.
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Stargardt P, Striedner G, Mairhofer J. Tunable expression rate control of a growth-decoupled T7 expression system by L-arabinose only. Microb Cell Fact 2021; 20:27. [PMID: 33522916 PMCID: PMC7852362 DOI: 10.1186/s12934-021-01512-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 01/07/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Precise regulation of gene expression is of utmost importance for the production of complex membrane proteins (MP), enzymes or other proteins toxic to the host cell. In this article we show that genes under control of a normally Isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible PT7-lacO promoter can be induced solely with L-arabinose in a newly constructed Escherichia coli expression host BL21-AI<gp2>, a strain based on the recently published approach of bacteriophage inspired growth-decoupled recombinant protein production. RESULTS Here, we show that BL21-AI<gp2> is able to precisely regulate protein production rates on a cellular level in an L-arabinose concentration-dependent manner and simultaneously allows for reallocation of metabolic resources due to L-arabinose induced growth decoupling by the phage derived inhibitor peptide Gp2. We have successfully characterized the system under relevant fed-batch like conditions in microscale cultivation (800 µL) and generated data proofing a relevant increase in specific yields for 6 different Escherichia coli derived MP-GFP fusion proteins by using online-GFP signals, FACS analysis, SDS-PAGE and western blotting. CONCLUSIONS In all cases tested, BL21-AI<gp2> outperformed the parental strain BL21-AI, operated in growth-associated production mode. Specific MP-GFP fusion proteins yields have been improved up to 2.7-fold. Therefore, this approach allows for fine tuning of MP production or expression of multi-enzyme pathways where e.g. particular stoichiometries have to be met to optimize product flux.
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Affiliation(s)
| | - Gerald Striedner
- Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190, Vienna, Austria
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Molecular Mechanisms of Phosphate Sensing, Transport and Signalling in Streptomyces and Related Actinobacteria. Int J Mol Sci 2021; 22:ijms22031129. [PMID: 33498785 PMCID: PMC7866108 DOI: 10.3390/ijms22031129] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/13/2022] Open
Abstract
Phosphorous, in the form of phosphate, is a key element in the nutrition of all living beings. In nature, it is present in the form of phosphate salts, organophosphates, and phosphonates. Bacteria transport inorganic phosphate by the high affinity phosphate transport system PstSCAB, and the low affinity PitH transporters. The PstSCAB system consists of four components. PstS is the phosphate binding protein and discriminates between arsenate and phosphate. In the Streptomyces species, the PstS protein, attached to the outer side of the cell membrane, is glycosylated and released as a soluble protein that lacks its phosphate binding ability. Transport of phosphate by the PstSCAB system is drastically regulated by the inorganic phosphate concentration and mediated by binding of phosphorylated PhoP to the promoter of the PstSCAB operon. In Mycobacterium smegmatis, an additional high affinity transport system, PhnCDE, is also under PhoP regulation. Additionally, Streptomyces have a duplicated low affinity phosphate transport system encoded by the pitH1–pitH2 genes. In this system phosphate is transported as a metal-phosphate complex in simport with protons. Expression of pitH2, but not that of pitH1 in Streptomyces coelicolor, is regulated by PhoP. Interestingly, in many Streptomyces species, three gene clusters pitH1–pstSCAB–ppk (for a polyphosphate kinase), are linked in a supercluster formed by nine genes related to phosphate metabolism. Glycerol-3-phosphate may be transported by the actinobacteria Corynebacterium glutamicum that contains a ugp gene cluster for glycerol-3-P uptake, but the ugp cluster is not present in Streptomyces genomes. Sugar phosphates and nucleotides are used as phosphate source by the Streptomyces species, but there is no evidence of the uhp gene involved in the transport of sugar phosphates. Sugar phosphates and nucleotides are dephosphorylated by extracellular phosphatases and nucleotidases. An isolated uhpT gene for a hexose phosphate antiporter is present in several pathogenic corynebacteria, such as Corynebacterium diphtheriae, but not in non-pathogenic ones. Phosphonates are molecules that contains phosphate linked covalently to a carbon atom through a very stable C–P bond. Their utilization requires the phnCDE genes for phosphonates/phosphate transport and genes for degradation, including those for the subunits of the C–P lyase. Strains of the Arthrobacter and Streptomyces genera were reported to degrade simple phosphonates, but bioinformatic analysis reveals that whole sets of genes for putative phosphonate degradation are present only in three Arthrobacter species and a few Streptomyces species. Genes encoding the C–P lyase subunits occur in several Streptomyces species associated with plant roots or with mangroves, but not in the laboratory model Streptomyces species; however, the phnCDE genes that encode phosphonates/phosphate transport systems are frequent in Streptomyces species, suggesting that these genes, in the absence of C–P lyase genes, might be used as surrogate phosphate transporters. In summary, Streptomyces and related actinobacteria seem to be less versatile in phosphate transport systems than Enterobacteria.
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Choudhary KS, Kleinmanns JA, Decker K, Sastry AV, Gao Y, Szubin R, Seif Y, Palsson BO. Elucidation of Regulatory Modes for Five Two-Component Systems in Escherichia coli Reveals Novel Relationships. mSystems 2020; 5:e00980-20. [PMID: 33172971 PMCID: PMC7657598 DOI: 10.1128/msystems.00980-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 10/20/2020] [Indexed: 11/27/2022] Open
Abstract
Escherichia coli uses two-component systems (TCSs) to respond to environmental signals. TCSs affect gene expression and are parts of E. coli's global transcriptional regulatory network (TRN). Here, we identified the regulons of five TCSs in E. coli MG1655: BaeSR and CpxAR, which were stimulated by ethanol stress; KdpDE and PhoRB, induced by limiting potassium and phosphate, respectively; and ZraSR, stimulated by zinc. We analyzed RNA-seq data using independent component analysis (ICA). ChIP-exo data were used to validate condition-specific target gene binding sites. Based on these data, we do the following: (i) identify the target genes for each TCS; (ii) show how the target genes are transcribed in response to stimulus; and (iii) reveal novel relationships between TCSs, which indicate noncognate inducers for various response regulators, such as BaeR to iron starvation, CpxR to phosphate limitation, and PhoB and ZraR to cell envelope stress. Our understanding of the TRN in E. coli is thus notably expanded.IMPORTANCE E. coli is a common commensal microbe found in the human gut microenvironment; however, some strains cause diseases like diarrhea, urinary tract infections, and meningitis. E. coli's two-component systems (TCSs) modulate target gene expression, especially related to virulence, pathogenesis, and antimicrobial peptides, in response to environmental stimuli. Thus, it is of utmost importance to understand the transcriptional regulation of TCSs to infer bacterial environmental adaptation and disease pathogenicity. Utilizing a combinatorial approach integrating RNA sequencing (RNA-seq), independent component analysis, chromatin immunoprecipitation coupled with exonuclease treatment (ChIP-exo), and data mining, we suggest five different modes of TCS transcriptional regulation. Our data further highlight noncognate inducers of TCSs, which emphasizes the cross-regulatory nature of TCSs in E. coli and suggests that TCSs may have a role beyond their cognate functionalities. In summary, these results can lead to an understanding of the metabolic capabilities of bacteria and correctly predict complex phenotype under diverse conditions, especially when further incorporated with genome-scale metabolic models.
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Affiliation(s)
- Kumari Sonal Choudhary
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Julia A Kleinmanns
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Katherine Decker
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Anand V Sastry
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Ye Gao
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Richard Szubin
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Yara Seif
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, San Diego, California, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
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Stosiek N, Talma M, Klimek-Ochab M. Carbon-Phosphorus Lyase-the State of the Art. Appl Biochem Biotechnol 2020; 190:1525-1552. [PMID: 31792787 DOI: 10.1007/s12010-019-03161-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 10/23/2019] [Indexed: 11/27/2022]
Abstract
Organophosphonates are molecules that contain a very chemically stable carbon-phosphorus (C-P) bond. Microorganisms can utilize phosphonates as potential source of crucial elements for their growth, as developed several pathways to metabolize these compounds. One among these pathways is catalyzed by C-P lyase complex, which has a broad substrate specifity; therefore, it has a wide application in degradation of herbicides deposited in the environment, such as glyphosate. This multi-enzyme system accurately recognized in Escherichia coli and genetic studies have demonstrated that it is encoded by phn operon containing 14 genes (phnC-phnP). The phn operon is a member of the Pho regulon induced by phosphate starvation. Ability to degradation of phosphonates is also found in other microorganisms, especially soil and marine bacteria, that have homologous genes to those in E. coli. Despite the existence of differences in structure and composition of phn gene cluster, each of these strains contains phnGHIJKLM genes necessary in the C-P bond cleavage mechanism. The review provides a detailed description and summary of achievements on the C-P lyase enzymatic pathway over the last 50 years.
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Affiliation(s)
- Natalia Stosiek
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland.
| | - Michał Talma
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
| | - Magdalena Klimek-Ochab
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
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Mastrorilli E, Petrin S, Orsini M, Longo A, Cozza D, Luzzi I, Ricci A, Barco L, Losasso C. Comparative genomic analysis reveals high intra-serovar plasticity within Salmonella Napoli isolated in 2005-2017. BMC Genomics 2020; 21:202. [PMID: 32131727 PMCID: PMC7057659 DOI: 10.1186/s12864-020-6588-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 02/18/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Salmonella enterica subsp. enterica serovar Napoli (S. Napoli) is among the top serovars causing human infections in Italy, although it is relatively uncommon in other European countries; it is mainly isolated from humans and the environment, but neither the reservoir nor its route of infection are clearly defined. This serovar is characterized by high genomic diversity, and molecular evidences revealed important similarities with typhoidal serovars. RESULTS 179 S. Napoli genomes as well as 239 genomes of typhoidal and non-typhoidal serovars were analyzed in a comparative genomic study. Phylogenetic analysis and draft genome characterization in terms of Multi Locus Sequence Typing (MLST), plasmid replicons, Salmonella Pathogenicity Islands (SPIs), antimicrobial resistance genes (ARGs), phages, biocide and metal-tolerance genes confirm the high genetic variability of S. Napoli, also revealing a within-serovar phylogenetic structure more complex than previously known. Our work also confirms genomic similarity of S. Napoli to typhoidal serovars (S. Typhi and S. Paratyphi A), with S. Napoli samples clustering primarily according to ST, each being characterized by specific genomic traits. Moreover, two major subclades of S. Napoli can be clearly identified, with ST-474 being biphyletic. All STs span among isolation sources and years of isolation, highlighting the challenge this serovar poses to define its epidemiology and evolution. Altogether, S. Napoli strains carry less SPIs and less ARGs than other non-typhoidal serovars and seldom acquire plasmids. However, we here report the second case of an extended-spectrum β-lactamases (ESBLs) producing S. Napoli strain and the first cases of multidrug resistant (MDR) S. Napoli strains, all isolated from humans. CONCLUSIONS Our results provide evidence of genomic plasticity of S. Napoli, highlighting genomic similarity with typhoidal serovars and genomic features typical of non-typhoidal serovars, supporting the possibility of survival in different niches, both enteric and non-enteric. Presence of horizontally acquired ARGs and MDR profiles rises concerns regarding possible selective pressure exerted by human environment on this pathogen.
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Affiliation(s)
- Eleonora Mastrorilli
- Istituto Zooprofilattico Sperimentale delle Venezie, Microbial Ecology Unit, Legnaro, Italy
- Present address: European Molecular Biology Laboratory, Structural and Computational Biology Unit, Heidelberg, Germany
| | - Sara Petrin
- Istituto Zooprofilattico Sperimentale delle Venezie, Microbial Ecology Unit, Legnaro, Italy
| | - Massimiliano Orsini
- Istituto Zooprofilattico Sperimentale delle Venezie, Microbial Ecology Unit, Legnaro, Italy.
| | - Alessandra Longo
- Istituto Zooprofilattico Sperimentale delle Venezie, Microbial Ecology Unit, Legnaro, Italy
| | - Debora Cozza
- Istituto Zooprofilattico Sperimentale del Mezzogiorno, Portici, Italy
| | - Ida Luzzi
- Istituto Superiore di Sanità, Rome, Italy
| | - Antonia Ricci
- Istituto Zooprofilattico Sperimentale delle Venezie, Food Safety Department, Legnaro, Italy
| | - Lisa Barco
- Istituto Zooprofilattico Sperimentale delle Venezie, Food Safety Department, Legnaro, Italy
| | - Carmen Losasso
- Istituto Zooprofilattico Sperimentale delle Venezie, Microbial Ecology Unit, Legnaro, Italy
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Abstract
Phosphorus is required for many biological molecules and essential functions, including DNA replication, transcription of RNA, protein translation, posttranslational modifications, and numerous facets of metabolism. In order to maintain the proper level of phosphate for these processes, many bacteria adapt to changes in environmental phosphate levels. The mechanisms for sensing phosphate levels and adapting to changes have been extensively studied for multiple organisms. The phosphate response of Escherichia coli alters the expression of numerous genes, many of which are involved in the acquisition and scavenging of phosphate more efficiently. This review shares findings on the mechanisms by which E. coli cells sense and respond to changes in environmental inorganic phosphate concentrations by reviewing the genes and proteins that regulate this response. The PhoR/PhoB two-component signal transduction system is central to this process and works in association with the high-affinity phosphate transporter encoded by the pstSCAB genes and the PhoU protein. Multiple models to explain how this process is regulated are discussed.
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Murota C, Fujiwara S, Tsujishita M, Urabe K, Takayanagi S, Aoki M, Umemura T, Eaton-Rye JJ, Pitt FD, Tsuzuki M. Hyper-resistance to arsenate in the cyanobacterium Synechocystis sp. PCC 6803 is influenced by the differential kinetics of its pst-ABC transporters and external phosphate concentration exposure. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Zeng Q, Xie J, Li Y, Gao T, Xu C, Wang Q. Comparative genomic and functional analyses of four sequenced Bacillus cereus genomes reveal conservation of genes relevant to plant-growth-promoting traits. Sci Rep 2018; 8:17009. [PMID: 30451927 PMCID: PMC6242881 DOI: 10.1038/s41598-018-35300-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022] Open
Abstract
Some Bacillus strains function as predominant plant-growth-promoting rhizobacteria. Bacillus cereus 905 is a rod-shaped Gram-positive bacterium isolated from wheat rhizosphere and is a rhizobacterium that exhibits significant plant-growth-promoting effects. Species belonging to the genus Bacillus are observed in numerous different habitats. Several papers on B. cereus are related to pathogens that causes food-borne illness and industrial applications. However, genomic analysis of plant-associated B. cereus has yet to be reported. Here, we conducted a genomic analysis comparing strain 905 with three other B. cereus strains and investigate the genomic characteristics and evolution traits of the species in different niches. The genome sizes of four B. cereus strains range from 5.38 M to 6.40 M, and the number of protein-coding genes varies in the four strains. Comparisons of the four B. cereus strains reveal 3,998 core genes. The function of strain-specific genes are related to carbohydrate, amino acid and coenzyme metabolism and transcription. Analysis of single nucleotide polymorphisms (SNPs) indicates local diversification of the four strains. SNPs are unevenly distributed throughout the four genomes, and function interpretation of regions with high SNP density coincides with the function of strain-specific genes. Detailed analysis indicates that certain SNPs contribute to the formation of strain-specific genes. By contrast, genes related to plant-growth-promoting traits are highly conserved. This study shows the genomic differences between four strains from different niches and provides an in-depth understanding of the genome architecture of these species, thus facilitating genetic engineering and agricultural applications in the future.
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Affiliation(s)
- Qingchao Zeng
- Key Laboratory of Plant Pathology, Ministry of Agriculture, College of Plant Protection, China Agricultural University, Beijing, 100193, P. R. China
| | - Jianbo Xie
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, P. R. China
| | - Yan Li
- Key Laboratory of Plant Pathology, Ministry of Agriculture, College of Plant Protection, China Agricultural University, Beijing, 100193, P. R. China
| | - Tantan Gao
- Key Laboratory of Plant Pathology, Ministry of Agriculture, College of Plant Protection, China Agricultural University, Beijing, 100193, P. R. China
| | - Cheng Xu
- Key Laboratory of Plant Pathology, Ministry of Agriculture, College of Plant Protection, China Agricultural University, Beijing, 100193, P. R. China
| | - Qi Wang
- Key Laboratory of Plant Pathology, Ministry of Agriculture, College of Plant Protection, China Agricultural University, Beijing, 100193, P. R. China.
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Kamravamanesh D, Kovacs T, Pflügl S, Druzhinina I, Kroll P, Lackner M, Herwig C. Increased poly-β-hydroxybutyrate production from carbon dioxide in randomly mutated cells of cyanobacterial strain Synechocystis sp. PCC 6714: Mutant generation and characterization. BIORESOURCE TECHNOLOGY 2018; 266:34-44. [PMID: 29957289 DOI: 10.1016/j.biortech.2018.06.057] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 06/08/2023]
Abstract
Photosynthetic Poly-β-hydroxybutyrate (PHB) productivity in cyanobacteria needs to be increased to make cyanobacterial derived bioplastics economically feasible and competitive with petroleum-based plastics. In this study, high PHB yielding mutants of Synechocystis sp. PCC 6714 have been generated by random mutagenesis, using UV light as a mutagen. The selection of strains was based on PHB content induced by nitrogen and phosphorus starvation. The fast growing mutant MT_a24 exhibited more than 2.5-fold higher PHB productivity than that of the wild-type, attaining values of 37 ± 4% dry cell weight PHB. The MT_a24 was characterized for phenotypes, CO2 uptake rate and gene expression levels using quantitative PCR. Genome sequencing showed that UV mutagenesis treatment resulted in a point mutation in the ABC-transport complex, phosphate-specific transport system integral membrane protein A (PstA). The MT_a24 shows potential for industrial production of PHB and also for carbon capture from the atmosphere or point sources.
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Affiliation(s)
- Donya Kamravamanesh
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, 1060 Vienna, Austria; Lackner Ventures & Consulting GmbH, Hofherr Schrantz Gasse 2, 1210 Vienna, Austria
| | - Tamas Kovacs
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, 1060 Vienna, Austria
| | - Stefan Pflügl
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, 1060 Vienna, Austria.
| | - Irina Druzhinina
- Institute of Chemical, Environmental and Bioscience Engineering, Research Group for Microbiology and Applied Genomics, Technische Universität Wien, 1060 Vienna, Austria
| | - Paul Kroll
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, 1060 Vienna, Austria; CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses, Technische Universität Wien, 1060 Vienna, Austria
| | - Maximilian Lackner
- Lackner Ventures & Consulting GmbH, Hofherr Schrantz Gasse 2, 1210 Vienna, Austria; University of Applied Sciences FH Technikum Wien, 1200 Vienna, Austria
| | - Christoph Herwig
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, 1060 Vienna, Austria; CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses, Technische Universität Wien, 1060 Vienna, Austria
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17
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Zhang Y, Zhang Y, Li P, Wang Y, Wang J, Shao Z, Zhao G. GlnR positive transcriptional regulation of the phosphate-specific transport system pstSCAB in Amycolatopsis mediterranei U32. Acta Biochim Biophys Sin (Shanghai) 2018; 50:757-765. [PMID: 30007316 DOI: 10.1093/abbs/gmy073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Indexed: 11/14/2022] Open
Abstract
Amycolatopsis mediterranei U32 is an important industrial strain for the production of rifamycin SV. Rifampicin, a derivative of rifamycin SV, is commonly used to treat mycobacterial infections. Although phosphate has long been known to affect rifamycin biosynthesis, phosphate transport, metabolism, and regulation are poorly understood in A. mediterranei. In this study, the functional phosphate transport system pstSCAB was isolated by RNA sequencing and inactivated by insertion mutation in A. mediterranei U32. The mycelium morphology changed from a filamentous shape in the wild-type and pstS1+ strains to irregular swollen shape at the end of filamentous in the ΔpstS1 strain. RT-PCR assay revealed that pstSCAB genes are co-transcribed as a polycistronic messenger. The pstSCAB transcription was significantly activated by nitrate supplementation and positively regulated by GlnR which is a global regulator of nitrogen metabolism in actinomycetes. At the same time, the yield of rifamycin SV decreased after mutation (ΔpstS1) compared with wild-type U32, which indicated a strong connection among phosphate metabolism, nitrogen metabolism, and rifamycin production in actinomycetes.
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Affiliation(s)
- Yuhui Zhang
- School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, China
- Department of Life Sciences, Henan Institute of Science and Technology, Xinxiang, China
| | - Yixuan Zhang
- School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, China
| | - Peng Li
- Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ying Wang
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Jin Wang
- Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhihui Shao
- Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guoping Zhao
- School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, China
- Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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18
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PhoU2 but Not PhoU1 as an Important Regulator of Biofilm Formation and Tolerance to Multiple Stresses by Participating in Various Fundamental Metabolic Processes in Staphylococcus epidermidis. J Bacteriol 2017; 199:JB.00219-17. [PMID: 28947672 PMCID: PMC5686610 DOI: 10.1128/jb.00219-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/18/2017] [Indexed: 12/17/2022] Open
Abstract
PhoU, a conserved protein that has been proposed to coordinate phosphate import, is a negative regulator of drug tolerance in most bacteria. In Staphylococcus epidermidis, the role of PhoU in biofilm formation and drug tolerance has not yet been investigated. Two PhoU homologs in the genome of S. epidermidis have been identified by the presence of the conserved motif E(D)XXXD of PhoU. We separately constructed ΔphoU1 and ΔphoU2 mutants of S. epidermidis strain 1457. The ΔphoU2 mutant displayed growth retardation, a weakened biofilm formation capacity, a higher sensitivity to H2O2, and reduced tolerance to multiple antibiotics. However, deletion of phoU1 had no effect on those. We compared the transcriptome profiles of the ΔphoU2 and ΔphoU1 mutants with that of the parent strain. In the ΔphoU2 mutant, expression of genes related to inorganic phosphate uptake was significantly upregulated (pst operon) and the levels of intracellular inorganic polyphosphate (polyP) were increased. In the ΔphoU2 mutant, expression of enzymes in the pentose phosphate pathway (PPP) was downregulated and less NADP (NADPH) was detected, consistent with the high sensitivity to H2O2 and the growth retardation of the ΔphoU2 mutant. The upregulated expression of ATP synthase was consistent with the high intracellular ATP content in the ΔphoU2 mutant, which may have been related to the lower drug tolerance of the ΔphoU2 mutant. This study demonstrates that PhoU2, but not PhoU1, in S. epidermidis regulates bacterial growth, biofilm formation, oxidative stress, and drug tolerance in association with alterations to inorganic phosphate metabolism, the pentose phosphate pathway, galactose metabolism, the tricarboxylic acid (TCA) or citric cycle, glycolysis and gluconeogenesis, and respiratory reactions. IMPORTANCE PhoU is widely conserved throughout the bacterial kingdom and plays an important role in response to stress and metabolic maintenance. In our study, two PhoU homologs were found in S. epidermidis. The function of phoU2, but not phoU1, in S. epidermidis is related to growth, drug tolerance, the oxidative stress response, polyP levels, and ATP accumulation. In addition, phoU2 regulates biofilm formation. Hence, phoU2 is a regulator of both drug tolerance and biofilm formation, which are two bacterial properties that present major challenges to the clinical treatment of infections. Analysis of differential gene expression revealed that phoU2 is involved in fundamental metabolic processes, such as the PPP pathway. These findings indicate that phoU2 is a crucial regulator in S. epidermidis.
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da Costa Vasconcelos FN, Padilla G, Spira B. Chromobacterium violaceum adaptation to low-phosphate conditions. Arch Microbiol 2016; 198:269-77. [PMID: 26793969 DOI: 10.1007/s00203-016-1188-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/21/2015] [Accepted: 01/08/2016] [Indexed: 01/18/2023]
Abstract
Chromobacterium violaceum is a free-living bacterium that inhabits low-nutrient environments such as the Amazon basin. Bacteria respond to phosphate (Pi) shortage by expressing a range of genes involved in Pi uptake and assimilation, known as the PHO regulon. Several PHO regulon genes have been annotated in the genome of C. violaceum. Here we show that C. violaceum is extremely well adapted to low-Pi conditions. Remarkably, this bacterium is able to grow in media containing only traces of Pi. The PHO regulon genes are induced upon Pi depletion, but the bacteria continued to grow under these conditions. Unlike other Proteobacteria hitherto analyzed, neither PstS nor PhoU play a role in the repression of the PHO regulon under Pi excess.
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Affiliation(s)
- Fernanda Nogales da Costa Vasconcelos
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, São Paulo, SP, CEP:05508-900, Brazil
| | - Gabriel Padilla
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, São Paulo, SP, CEP:05508-900, Brazil
| | - Beny Spira
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, São Paulo, SP, CEP:05508-900, Brazil.
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20
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phoU inactivation in Pseudomonas aeruginosa enhances accumulation of ppGpp and polyphosphate. Appl Environ Microbiol 2015; 81:3006-15. [PMID: 25710363 DOI: 10.1128/aem.04168-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/13/2015] [Indexed: 12/28/2022] Open
Abstract
Inorganic polyphosphate (polyP) is a linear polymer composed of several molecules of orthophosphate (Pi) linked by energy-rich phosphoanhydride bonds. In Pseudomonas aeruginosa, Pi is taken up by the ABC transporter Pst, encoded by an operon consisting of five genes. The first four genes encode proteins involved in the transport of Pi and the last gene of the operon, phoU, codes for a protein which exact function is unknown. We show here that the inactivation of phoU in P. aeruginosa enhanced Pi removal from the medium and polyP accumulation. The phoU mutant also accumulated high levels of the alarmone guanosine tetraphosphate (ppGpp), which in turn increased the buildup of polyP. In addition, phoU inactivation had several pleiotropic effects, such as reduced growth rate and yield and increased sensitivity to antibiotics and stresses. However, biofilm formation was not affected by the phoU mutation.
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21
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Chhabra S, Brazil D, Morrissey J, Burke JI, O'Gara F, N Dowling D. Characterization of mineral phosphate solubilization traits from a barley rhizosphere soil functional metagenome. Microbiologyopen 2013; 2:717-24. [PMID: 23894099 PMCID: PMC3831634 DOI: 10.1002/mbo3.110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/12/2013] [Accepted: 06/17/2013] [Indexed: 11/11/2022] Open
Abstract
Mineral phosphate solubilization (MPS) microorganisms are important for their provision of orthophosphate anions for plant growth promotion activity in soil. In this study, we applied a functional metagenomic approach to identify this trait directly from the microbiome in barley rhizosphere soil that had not received P fertilizer over a 15-year period. A fosmid system was used to clone the metagenome of which 18,000 clones (~666 Mb of DNA) was screened for MPS. Functional assays and High Performance Liquid Chromatography analysis recognized gluconic acid production and MPS activity in the range 24.8-77.1 mmol/L and 27.6-38.16 μg/mL, respectively, when screened in an Escherichia coli host (at frequency of one MPS-positive clone hit per 114 Mb DNA tested). The MPS clones (with average insert size of ~37 kb) were analysed by 454 Roche sequencing and annotated. A number of genes/operons with homology to Phosphorous (P) uptake, regulatory and solubilization mechanisms were identified, linking the MPS function to the uncultivated microbiome present in barley rhizosphere soil.
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Affiliation(s)
- Sagar Chhabra
- Department of Science and Health, Institute of Technology Carlow, Carlow, Ireland
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22
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Analysis of conformational motions and residue fluctuations for Escherichia coli ribose-binding protein revealed with elastic network models. Int J Mol Sci 2013; 14:10552-69. [PMID: 23698778 PMCID: PMC3676853 DOI: 10.3390/ijms140510552] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/24/2013] [Accepted: 04/25/2013] [Indexed: 12/19/2022] Open
Abstract
The ribose-binding protein (RBP) is a sugar-binding bacterial periplasmic protein whose function is associated with a large allosteric conformational change from an open to a closed conformation upon binding to ribose. The open (ligand-free) and closed (ligand-bound) forms of RBP have been found. Here we investigate the conformational motions and residue fluctuations of the RBP by analyzing the modes of motion with two coarse-grained elastic network models, the Gaussian Network Model (GNM) and Anisotropic Network Model (ANM). The calculated B-factors in both the calculated models are in good agreement with the experimentally determined B-factors in X-ray crystal structures. The slowest mode analysis by GNM shows that both forms have the same motion hinge axes around residues Ser103, Gln235, Asp264 and the two domains of both structures have similar fluctuation range. The superposition of the first three dominant modes of ANM, consisting of the rotating, bending and twisting motions of the two forms, accounts for large rearrangement of domains from the ligand-free (open) to ligand-bound (closed) conformation and thus constitutes a critical component of the RBP's functions. By analyzing cross-correlations between residue fluctuation and the difference-distance plot, it is revealed that the conformational change can be described as a rigid rotation of the two domains with respect to each other, whereas the internal structure of the two domains remains largely intact. The results directly indicate that the dominant dynamic characteristics of protein structures can be captured from their static native state using coarse-grained models.
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Biological Removal of Phosphate at Low Concentrations Using Recombinant Escherichia coli Expressing Phosphate-Binding Protein in Periplasmic Space. Appl Biochem Biotechnol 2013; 171:1170-7. [DOI: 10.1007/s12010-013-0187-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 03/05/2013] [Indexed: 11/26/2022]
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Cosentino-Gomes D, Meyer-Fernandes JR. Ecto-phosphatases in protozoan parasites: possible roles in nutrition, growth and ROS sensing. J Bioenerg Biomembr 2011; 43:89-92. [PMID: 21253843 DOI: 10.1007/s10863-011-9334-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cellular plasma membrane contains enzymes whose active sites face the external medium rather than the cytoplasm. The activities of these enzymes, referred to as ecto-enzymes, can be measured using living cells. Ecto-phosphatases are ecto-enzymes that presumably hydrolyze extracellular phosphorylated substrates, releasing free inorganic phosphate. Although, several alternative functions have been suggested for these enzymes, such as participation in proliferation, differentiation, adhesion, virulence, and infection, little is known about the physiological roles of these enzymes in protozoa parasites. In this review, we discuss the principal features of ecto-phosphatases in protozoan parasites that are causative agents of important diseases such as Chagas' disease, leishmaniasis, amoebiasis, giardiasis, trichomoniasis and, sleeping sickness.
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Affiliation(s)
- Daniela Cosentino-Gomes
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Hove-Jensen B, McSorley FR, Zechel DL. Physiological role of phnP-specified phosphoribosyl cyclic phosphodiesterase in catabolism of organophosphonic acids by the carbon-phosphorus lyase pathway. J Am Chem Soc 2011; 133:3617-24. [PMID: 21341651 DOI: 10.1021/ja1102713] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In Escherichia coli , internalization and catabolism of organophosphonicacids are governed by the 14-cistron phnCDEFGHIJKLMNOP operon. The phnP gene product was previously shown to encode a phosphodiesterase with unusual specificity toward ribonucleoside 2',3'-cyclic phosphates. Furthermore, phnP displays shared synteny with phnN across bacterial phn operons. Here the role of PhnP was examined by (31)P NMR spectrometry on the culture supernatants of E. coli phn mutants grown in the presence of alkylphosphonic acid or phosphite. The addition of any of these alkylphosphonic acids or phosphite resulted in the accumulation of α-D-ribosyl 1,2-cyclic phosphate and α-D-ribosyl 1-alkylphosphonate in a phnP mutant strain. Additionally, α-D-ribosyl 1-ethylphosphonate was observed to accumulate in a phnJ mutant strain when it was fed ethylphosphonic acid. Purified PhnP was shown to regiospecifically convert α-D-ribosyl 1,2-cyclic phosphate to α-D-ribosyl 1-phosphate. Radiolabeling studies revealed that 5-phospho-α-D-ribosyl 1,2-cyclic phosphate also accumulates in a phnP mutant. This compound was synthesized and shown to be regiospecifically converted by PhnP to α-D-ribosyl 1,5-bisphosphate. It is also shown that organophosphonate catabolism is dependent on the synthesis of 5-phospho-α-D-ribosyl 1-diphosphate, suggesting that this phosphoribosyl donor is used to initiate the carbon-phosphorus (CP) lyase pathway. The results show that 5-phospho-α-D-ribosyl 1,2-cyclic phosphate is an intermediate of organophosphonic acid catabolism, and it is proposed that this compound derives from C-P bond cleavage of 5-phospho-α-D-ribosyl 1-alkylphosphonates by CP lyase.
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Affiliation(s)
- Bjarne Hove-Jensen
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6.
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Huang QY, Fang CW, Huang HQ. Alteration of heart tissue protein profiles in acute cadmium-treated scallops Patinopecten yessoensis. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2011; 60:90-98. [PMID: 20437039 DOI: 10.1007/s00244-010-9533-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2009] [Accepted: 04/12/2010] [Indexed: 05/29/2023]
Abstract
Cadmium (Cd) is an extremely toxic metal that induces a wide spectrum of toxic responses in organisms in the environment. In the present study, scallops (Patinopecten yessoensis), after acclimation for 1 week in the laboratory, were subjected to acute Cd chloride (CdCl₂) toxicity, and ultramorphological and proteomic changes in their heart tissues were analyzed and compared with those of the nonexposed control group. Electron microscopy showed that ultrastructures of the cytoplasm and mitochondria in scallop hearts were badly damaged, and two-dimensional gel electrophoresis showed 32 protein spots that were differentially expressed after exposure to 10 mg/l CdCl₂ for 24 h. Of these spots, 8 were upregulated, 16 were downregulated, and 8 showed low expression. Proteins from these spots were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry and database searching. The results indicated that these proteins are involved in the regulation of cell structure, transport, signal transduction, and metabolism. Among other things, four proteins-identified as amino acid adenosine triphosphate (ATP)-binding cassette transporter, glycerol-3-phosphate dehydrogenase (nicotinamide adenine dinucleotide phosphate), nicotinamide adenine dinucleotide oxidase, and ATPase-were demonstrated to be especially associated with Cd toxicity. Some of the other proteins observed in this work are of particular interest in terms of their responses to Cd, which have not been reported previously. These data may provide novel biomarkers for monitoring the Cd contamination level of flowing seawater as well as provide useful insights into the mechanisms of Cd toxicity.
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Affiliation(s)
- Qing-Yu Huang
- Department of Biochemistry and Biotechnology, Xiamen University, China
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Increased Pho regulon activation correlates with decreased virulence of an avian pathogenic Escherichia coli O78 strain. Infect Immun 2010; 78:5324-31. [PMID: 20921144 DOI: 10.1128/iai.00452-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) strains are associated with respiratory infections, septicemia, cellulitis, peritonitis, and other conditions, since colibacillosis manifests in many ways. The Pho regulon is jointly controlled by the two-component regulatory system PhoBR and by the phosphate-specific transport (Pst) system. To determine the specific roles of the PhoBR regulon and the Pst system in the pathogenesis of the APEC O78 strain χ7122, different phoBR and pst mutant strains were tested in vivo in chickens and in vitro for virulence traits. Mutations resulting in constitutive activation of the Pho regulon rendered strains more sensitive than the wild type to hydrogen peroxide and to the bactericidal effects of rabbit serum. In addition, production of type 1 fimbriae was also impaired in these strains. Using a chicken competitive infection model, all PhoB constitutive mutants were outcompeted by the wild-type parent, including strains containing a functional Pst system. Cumulative inactivation of the Pst system and the PhoB regulator resulted in a restoration of virulence. In addition, loss of the PhoB regulator alone did not affect virulence in the chicken infection model. Interestingly, the level of attenuation of the mutant strains correlated directly with the level of activation of the Pho regulon. Overall, results indicate that activation of the Pho regulon rather than phosphate transport by the Pst system plays a major role in the attenuation of the APEC O78 strain χ7122.
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Critzer FJ, D'Souza DH, Saxton AM, Golden DA. Increased transcription of the phosphate-specific transport system of Escherichia coli O157:H7 after exposure to sodium benzoate. J Food Prot 2010; 73:819-24. [PMID: 20501031 DOI: 10.4315/0362-028x-73.5.819] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sodium benzoate is a widely used food antimicrobial in drinks and fruit juices. A microarray study was conducted to determine the transcriptional response of Escherichia coli O157:H7 to 0.5% (wt/vol) sodium benzoate. E. coli O157:H7 grown in 150 ml of Luria-Bertani broth was exposed to 0% (control) and 0.5% sodium benzoate. Each treatment was duplicated and sampled at 0 (immediately after exposure), 5, 15, 30, and 60 min. Total RNA was extracted and analyzed with E. coli 2.0 Gene Chips. Significant ontology categories affected by sodium benzoate exposure were determined with JProGO software. The phosphate-specific transport (Pst) system transports inorganic phosphate into bacterial cells, under phosphate-limited conditions. The Pst system was found to be highly upregulated. Increased expression of the Pst system was observed after the short 5 min of exposure to sodium benzoate; pstS, pstA, pstB, and pstC genes were upregulated more than twofold (linear scale) at 5, 15, 30, and 60 min. Increased expression of several other efflux systems, such as AcrAB-TolC, was also observed. The Pst system may act as an efflux pump under these stress-adapted conditions, as well as increase transport of phosphorus to aid in DNA, RNA, ATP, and phospholipid production. Understanding adaptations of Escherichia coli O157:H7 under antimicrobial exposure is essential to better understand and implement methods to inhibit or control its survival in foods.
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Affiliation(s)
- Faith J Critzer
- Department of Food Science and Technology, The University of Tennessee, Knoxville, Tennessee 37996-4591, USA
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29
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Functional characterization of Synechocystis sp. strain PCC 6803 pst1 and pst2 gene clusters reveals a novel strategy for phosphate uptake in a freshwater cyanobacterium. J Bacteriol 2010; 192:3512-23. [PMID: 20435726 DOI: 10.1128/jb.00258-10] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Synechocystis sp. strain PCC 6803 possesses two putative ABC-type inorganic phosphate (P(i)) transporters with three associated P(i)-binding proteins (PBPs), SphX (encoded by sll0679), PstS1 (encoded by sll0680), and PstS2 (encoded by slr1247), organized in two spatially discrete gene clusters, pst1 and pst2. We used a combination of mutagenesis, gene expression, and radiotracer uptake analyses to functionally characterize the role of these PBPs and associated gene clusters. Quantitative PCR (qPCR) demonstrated that pstS1 was expressed at a high level in P(i)-replete conditions compared to sphX or pstS2. However, a P(i) stress shift increased expression of pstS2 318-fold after 48 h, compared to 43-fold for pstS1 and 37-fold for sphX. A shift to high-light conditions caused a transient increase of all PBPs, whereas N stress primarily increased expression of sphX. Interposon mutagenesis of each PBP demonstrated that disruption of pstS1 alone caused constitutive expression of pho regulon genes, implicating PstS1 as a major component of the P(i) sensing machinery. The pstS1 mutant was also transformation incompetent. (32)P(i) radiotracer uptake experiments using pst1 and pst2 deletion mutants showed that Pst1 acts as a low-affinity, high-velocity transporter (K(s), 3.7 + or - 0.7 microM; V(max), 31.18 + or - 3.96 fmol cell(-1) min(-1)) and Pst2 acts as a high-affinity, low-velocity system (K(s), 0.07 + or - 0.01 microM; V(max), 0.88 + or - 0.11 fmol cell(-1) min(-1)). These P(i) ABC transporters thus exhibit differences in both kinetic and regulatory properties, the former trait potentially dramatically increasing the dynamic range of P(i) transport into the cell, which has potential implications for our understanding of the ecological success of this key microbial group.
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Trypanosoma rangeli: Differential expression of ecto-phosphatase activities in response to inorganic phosphate starvation. Exp Parasitol 2010; 124:386-93. [DOI: 10.1016/j.exppara.2009.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 11/16/2009] [Accepted: 12/12/2009] [Indexed: 01/25/2023]
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Abstract
The urinary tract is among the most common sites of bacterial infection, and Escherichia coli is by far the most common species infecting this site. Individuals at high risk for symptomatic urinary tract infection (UTI) include neonates, preschool girls, sexually active women, and elderly women and men. E. coli that cause the majority of UTIs are thought to represent only a subset of the strains that colonize the colon. E. coli strains that cause UTIs are termed uropathogenic E. coli (UPEC). In general, UPEC strains differ from commensal E. coli strains in that the former possess extragenetic material, often on pathogenicity-associated islands (PAIs), which code for gene products that may contribute to bacterial pathogenesis. Some of these genes allow UPEC to express determinants that are proposed to play roles in disease. These factors include hemolysins, secreted proteins, specific lipopolysaccharide and capsule types, iron acquisition systems, and fimbrial adhesions. The current dogma of bacterial pathogenesis identifies adherence, colonization, avoidance of host defenses, and damage to host tissues as events vital for achieving bacterial virulence. These considerations, along with analysis of the E. coli CFT073, UTI89, and 536 genomes and efforts to identify novel virulence genes should advance the field significantly and allow for the development of a comprehensive model of pathogenesis for uropathogenic E. coli.Further study of the adaptive immune response to UTI will be especially critical to refine our understanding and treatment of recurrent infections and to develop vaccines.
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32
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Trypanosoma rangeli: A possible role for ecto-phosphatase activity on cell proliferation. Exp Parasitol 2009; 122:242-6. [DOI: 10.1016/j.exppara.2009.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 01/06/2009] [Accepted: 03/06/2009] [Indexed: 12/16/2022]
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Borrok MJ, Zhu Y, Forest KT, Kiessling LL. Structure-based design of a periplasmic binding protein antagonist that prevents domain closure. ACS Chem Biol 2009; 4:447-56. [PMID: 19348466 DOI: 10.1021/cb900021q] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Many receptors undergo ligand-induced conformational changes to initiate signal transduction. Periplasmic binding proteins (PBPs) are bacterial receptors that exhibit dramatic conformational changes upon ligand binding. These proteins mediate a wide variety of fundamental processes including transport, chemotaxis, and quorum sensing. Despite the importance of these receptors, no PBP antagonists have been identified and characterized. In this study, we identify 3-O-methyl-d-glucose as an antagonist of glucose/galactose-binding protein and demonstrate that it inhibits glucose chemotaxis in E. coli. Using small-angle X-ray scattering and X-ray crystallography, we show that this antagonist acts as a wedge. It prevents the large-scale domain closure that gives rise to the active signaling state. Guided by these results and the structures of open and closed glucose/galactose-binding protein, we designed and synthesized an antagonist composed of two linked glucose residues. These findings provide a blueprint for the design of new bacterial PBP inhibitors. Given the key role of PBPs in microbial physiology, we anticipate that PBP antagonists will have widespread uses as probes and antimicrobial agents.
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Gristwood T, Fineran PC, Everson L, Williamson NR, Salmond GP. The PhoBR two-component system regulates antibiotic biosynthesis in Serratia in response to phosphate. BMC Microbiol 2009; 9:112. [PMID: 19476633 PMCID: PMC2695467 DOI: 10.1186/1471-2180-9-112] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 05/28/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Secondary metabolism in Serratia sp. ATCC 39006 (Serratia 39006) is controlled via a complex network of regulators, including a LuxIR-type (SmaIR) quorum sensing (QS) system. Here we investigate the molecular mechanism by which phosphate limitation controls biosynthesis of two antibiotic secondary metabolites, prodigiosin and carbapenem, in Serratia 39006. RESULTS We demonstrate that a mutation in the high affinity phosphate transporter pstSCAB-phoU, believed to mimic low phosphate conditions, causes upregulation of secondary metabolism and QS in Serratia 39006, via the PhoBR two-component system. Phosphate limitation also activated secondary metabolism and QS in Serratia 39006. In addition, a pstS mutation resulted in upregulation of rap. Rap, a putative SlyA/MarR-family transcriptional regulator, shares similarity with the global regulator RovA (regulator of virulence) from Yersina spp. and is an activator of secondary metabolism in Serratia 39006. We demonstrate that expression of rap, pigA-O (encoding the prodigiosin biosynthetic operon) and smaI are controlled via PhoBR in Serratia 39006. CONCLUSION Phosphate limitation regulates secondary metabolism in Serratia 39006 via multiple inter-linked pathways, incorporating transcriptional control mediated by three important global regulators, PhoB, SmaR and Rap.
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Affiliation(s)
- Tamzin Gristwood
- Department of Microbiology & Immunology, University of Otago, Dunedin, New Zealand.
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35
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Employment of a promoter-swapping technique shows that PhoU modulates the activity of the PstSCAB2 ABC transporter in Escherichia coli. Appl Environ Microbiol 2008; 75:573-82. [PMID: 19047379 DOI: 10.1128/aem.01046-08] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Expression of the Pho regulon in Escherichia coli is induced in response to low levels of environmental phosphate (P(i)). Under these conditions, the high-affinity PstSCAB(2) protein (i.e., with two PstB proteins) is the primary P(i) transporter. Expression from the pstSCAB-phoU operon is regulated by the PhoB/PhoR two-component regulatory system. PhoU is a negative regulator of the Pho regulon; however, the mechanism by which PhoU accomplishes this is currently unknown. Genetic studies of phoU have proven to be difficult because deletion of the phoU gene leads to a severe growth defect and creates strong selection for compensatory mutations resulting in confounding data. To overcome the instability of phoU deletions, we employed a promoter-swapping technique that places expression of the phoBR two-component system under control of the P(tac) promoter and the lacO(ID) regulatory module. This technique may be generally applicable for controlling expression of other chromosomal genes in E. coli. Here we utilized P(phoB)::P(tac) and P(pstS)::P(tac) strains to characterize phenotypes resulting from various DeltaphoU mutations. Our results indicate that PhoU controls the activity of the PstSCAB(2) transporter, as well as its abundance within the cell. In addition, we used the P(phoB)::P(tac) DeltaphoU strain as a platform to begin characterizing new phoU mutations in plasmids.
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36
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Bellenger JP, Wichard T, Kraepiel AML. Vanadium requirements and uptake kinetics in the dinitrogen-fixing bacterium Azotobacter vinelandii. Appl Environ Microbiol 2008; 74:1478-84. [PMID: 18192412 PMCID: PMC2258613 DOI: 10.1128/aem.02236-07] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 01/01/2008] [Indexed: 11/20/2022] Open
Abstract
Vanadium is a cofactor in the alternative V-nitrogenase that is expressed by some N(2)-fixing bacteria when Mo is not available. We investigated the V requirements, the kinetics of V uptake, and the production of catechol compounds across a range of concentrations of vanadium in diazotrophic cultures of the soil bacterium Azotobacter vinelandii. In strain CA11.70, a mutant that expresses only the V-nitrogenase, V concentrations in the medium between 10(-8) and 10(-6) M sustain maximum growth rates; they are limiting below this range and toxic above. A. vinelandii excretes in its growth medium micromolar concentrations of the catechol siderophores azotochelin and protochelin, which bind the vanadate oxoanion. The production of catechols increases when V concentrations become toxic. Short-term uptake experiments with the radioactive isotope (49)V show that bacteria take up the V-catechol complexes through a regulated transport system(s), which shuts down at high V concentrations. The modulation of the excretion of catechols and of the uptake of the V-catechol complexes allows A. vinelandii to precisely manage its V homeostasis over a range of V concentrations, from limiting to toxic.
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Affiliation(s)
- J P Bellenger
- Chemistry Department, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
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37
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Lubelski J, Konings WN, Driessen AJM. Distribution and physiology of ABC-type transporters contributing to multidrug resistance in bacteria. Microbiol Mol Biol Rev 2007; 71:463-76. [PMID: 17804667 PMCID: PMC2168643 DOI: 10.1128/mmbr.00001-07] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Membrane proteins responsible for the active efflux of structurally and functionally unrelated drugs were first characterized in higher eukaryotes. To date, a vast number of transporters contributing to multidrug resistance (MDR transporters) have been reported for a large variety of organisms. Predictions about the functions of genes in the growing number of sequenced genomes indicate that MDR transporters are ubiquitous in nature. The majority of described MDR transporters in bacteria use ion motive force, while only a few systems have been shown to rely on ATP hydrolysis. However, recent reports on MDR proteins from gram-positive organisms, as well as genome analysis, indicate that the role of ABC-type MDR transporters in bacterial drug resistance might be underestimated. Detailed structural and mechanistic analyses of these proteins can help to understand their molecular mode of action and may eventually lead to the development of new strategies to counteract their actions, thereby increasing the effectiveness of drug-based therapies. This review focuses on recent advances in the analysis of ABC-type MDR transporters in bacteria.
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Affiliation(s)
- Jacek Lubelski
- Department of Molecular Microbiology, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands
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Affiliation(s)
- Andrea K. White
- Department of Biological Sciences, California State University, Chico, California 95928-0515;
| | - William W. Metcalf
- Department of Microbiology and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801;
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Rizk SS, Cuneo MJ, Hellinga HW. Identification of cognate ligands for the Escherichia coli phnD protein product and engineering of a reagentless fluorescent biosensor for phosphonates. Protein Sci 2006; 15:1745-51. [PMID: 16751609 PMCID: PMC2242554 DOI: 10.1110/ps.062135206] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The Escherichia coli phnD gene is hypothesized to code for the periplasmic binding component of a phosphonate uptake system. Here we report the characterization of the phosphonate-binding properties of the phnD protein product. We find that PhnD exhibits high affinity for 2-aminoethylphosphonate (5 nM), the most commonly occurring natural phosphonate produced by lower eukaryotes, but also binds several other phosphonates with micromolar affinities. A significant number of man-made phosphonates, such as insecticides and chemical warfare agents, are chemical threats and environmental pollutants. Consequently, there is an interest in developing methods for the detection and bioremediation of phosphonates. Bacterial periplasmic-binding proteins have been utilized for developing reagentless biosensors that report analytes by coupling ligand-binding events to changes in the emission properties of a covalently conjugated environmentally-sensitive fluorophore. Several PhnD conjugates described here show large changes in fluorescence upon binding to methylphosphonate (MP), with two conjugates exhibiting up to 50% decrease in emission intensity. Since MP is the final degradation product of many nerve agents, these PhnD conjugates can function as components in a biosensor system for chemical warfare agents.
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Affiliation(s)
- Shahir S Rizk
- Duke University Medical Center, Department of Biochemistry, Durham, NC 27710, USA
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40
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Buckles EL, Wang X, Lockatell CV, Johnson DE, Donnenberg MS. PhoU enhances the ability of extraintestinal pathogenic Escherichia coli strain CFT073 to colonize the murine urinary tract. MICROBIOLOGY-SGM 2006; 152:153-160. [PMID: 16385125 DOI: 10.1099/mic.0.28281-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The phoU gene is the last cistron in the pstSCAB-phoU operon and functions as a negative regulator of the Pho regulon. The authors previously identified a phoU mutant of extraintestinal pathogenic Escherichia coli strain CFT073 and demonstrated that this mutant was attenuated for survival in the murine model of ascending urinary tract infection. It is hypothesized that the PhoU protein might serve as a urovirulence factor by indirectly affecting the expression of virulence-related genes. In this study, the phoU mutant was further characterized and PhoU was confirmed as a virulence factor. Western blot analysis demonstrated that insertion of the transposon in the phoU gene disrupted the expression of PhoU. The phoU mutant had derepressed alkaline phosphatase activity under phosphate-excess and -limiting conditions. In single-challenge murine ascending urinary tract infection experiments, quantitative cultures of urine, bladder and kidney revealed no significant differences between the phoU mutant strain and the wild-type strain CFT073. However, in competitive colonization experiments, the phoU mutant strain was significantly out-competed by the wild-type strain in the kidneys and urine and recovered in lower amount in the bladder. Complementation of the phoU mutant with a plasmid containing the wild-type phoU gene restored the expression of PhoU and alkaline phosphate activity to wild-type levels and no significant difference in colonization was observed between the phoU mutant containing the complementing plasmid and wild-type in competitive colonization experiments. In human urine, the phoU mutant and wild-type grew comparably when inoculated independently, indicating that the attenuation observed was not due to a general growth defect. However, as observed in vivo, the wild-type out-competed the phoU mutant in competition growth experiments in human urine. These data indicate that PhoU contributes to efficient colonization of the murine urinary tract and add PhoU to a short list of confirmed urovirulence factors.
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Affiliation(s)
- Eric L Buckles
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, HSF II, 20 Penn Street, Baltimore, MD 21201, USA
| | - Xiaolin Wang
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, HSF II, 20 Penn Street, Baltimore, MD 21201, USA
| | - C Virginia Lockatell
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, HSF II, 20 Penn Street, Baltimore, MD 21201, USA
| | - David E Johnson
- Department of Veterans Affairs, Baltimore, MD 21201, USA
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, HSF II, 20 Penn Street, Baltimore, MD 21201, USA
| | - Michael S Donnenberg
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, HSF II, 20 Penn Street, Baltimore, MD 21201, USA
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Wu H, Kosaka H, Kato J, Kuroda A, Ikeda T, Takiguchi N, Ohtake H. Cloning and characterization of Pseudomonas putida genes encoding the phosphate-specific transport system. J Biosci Bioeng 2005; 87:273-9. [PMID: 16232467 DOI: 10.1016/s1389-1723(99)80031-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/1998] [Accepted: 11/27/1998] [Indexed: 11/20/2022]
Abstract
The pstSCAB genes of Pseudomonas putida PRS2000, encoding the phosphate (Pi)-specific transport (Pst) system, were cloned. The pstS gene of Pseudomonas aeruginosa PAO1, of which the pstCAB genes had been cloned previously, was also cloned (Nikata, T. et al., Mol. Gen. Genet., 250, 692-698, 1996). The predicted translation products of the P. putida pstSCAB genes showed 83, 75, 78 and 88% amino acid identity with their P. aeruginosa counterparts. Two well-conserved Pho box sequences were found in the region upstream of the pstS gene (15/18 base identity with the consensus Pho box sequence) and in the intercistronic region between the pstS and pstC genes (11/18 base identity) of P. putida PRS2000. To investigate the functions of PstSCAB, the pstSC genes were inactivated by inserting a kanamycin resistance gene cassette into the chromosome of P. putida PRS2000. The resultant mutant, designated PNT1, failed to take up 32Pi even under conditions of Pi limitation. Strain PNT1 was also constitutive for alkaline phosphatase synthesis, as well as chemotaxis toward Pi, indicating that the Pst system is involved in the negative regulation of the pho regulon in P. putida. Although overexpression of the pstSCAB genes in P. putida PRS2000 resulted in decreased cell growth, this recombinant strain could remove Pi at a rate similar to that seen with the control strain.
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Affiliation(s)
- H Wu
- Department of Fermentation Technology, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8527, Japan
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Lamarche MG, Dozois CM, Daigle F, Caza M, Curtiss R, Dubreuil JD, Harel J. Inactivation of the pst system reduces the virulence of an avian pathogenic Escherichia coli O78 strain. Infect Immun 2005; 73:4138-45. [PMID: 15972503 PMCID: PMC1168596 DOI: 10.1128/iai.73.7.4138-4145.2005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O78 strains are frequently associated with extraintestinal diseases, such as airsacculitis and septicemia, in poultry, livestock, and humans. To understand the influence of the pst operon in the virulence of E. coli, we introduced mutations into the pst genes of the avian pathogenic E. coli (APEC) O78:K80 strain chi7122 by allelic exchange. The mutation of pst genes led to the constitutive expression of the Pho regulon. Furthermore, the virulence of APEC strain chi7122 in a chicken infection model was attenuated by inactivation of the Pst system. The pst mutant caused significantly fewer extraintestinal lesions in infected chickens, and bacterial numbers isolated from different tissues after infection were significantly lower for the mutant than for the wild-type strain. Moreover, resistance to the bactericidal effects of rabbit serum and acid shock was impaired in the pst mutant, in contrast to the wild-type strain. In addition, the MIC of polymyxin was twofold lower for the mutant than for the wild-type strain. Although the pst mutant demonstrated an increased susceptibility to rabbit serum, this strain was not killed by chicken serum, suggesting the presence of differences in host innate immune defenses and complement-mediated killing. In APEC O78 strain chi7122, a functional Pst system is required for full virulence and resistance to acid shock and polymyxin. Our results suggest that the mutation of pst genes induces a deregulation of phosphate sensing and changes in the cell surface composition that lead to decreased virulence, indicating the importance of the Pst system for the virulence of pathogenic E. coli strains from different hosts.
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Affiliation(s)
- Martin G Lamarche
- Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Université de Montréal, Faculté de Médecine Vétérinaire, C.P. 5000, Saint-Hyacinthe, Québec, Canada J2S 7C6
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Runyen-Janecky LJ, Boyle AM, Kizzee A, Liefer L, Payne SM. Role of the Pst system in plaque formation by the intracellular pathogen Shigella flexneri. Infect Immun 2005; 73:1404-10. [PMID: 15731038 PMCID: PMC1064976 DOI: 10.1128/iai.73.3.1404-1410.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In response to the host cell environment, the intracellular pathogen Shigella flexneri induces the expression of numerous genes, including those in the pst operon which is predicted to encode a high-affinity phosphate acquisition system that is expressed under reduced phosphate conditions. An S. flexneri pst mutant forms smaller plaques in Henle cell monolayers than does the parental strain. This mutant exhibited normal production and localization of the S. flexneri IcsA protein. The pst mutant had the same growth rate as the parental strain in both phosphate-reduced and phosphate-replete media in vitro and during the first 3 h of growth in Henle cells in vivo. During growth in phosphate-replete media, the PhoB regulon was constitutively expressed in the pst mutant but not the parental strain. This suggested that the inability of the S. flexneri pst mutant to form wild-type plaques in Henle cell monolayers may be due to aberrant expression of the PhoB regulon. A mutation in phoB was constructed in the S. flexneri pst mutant, and the phoB mutation suppressed the small plaque phenotype of the pst mutant. Additionally, a specific mutation (R220Q) was constructed in the pstA gene of the pst operon that was predicted to eliminate Pst-mediated phosphate transport but allow normal PhoB-regulated gene expression, based on the phenotype of an Escherichia coli strain harboring the same mutation. Addition of this pstA(R220Q) mutation to a S. flexneri pst mutant, as part of the pst operon, restored normal plaque formation and regulation of phoA expression.
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Peirs P, Lefèvre P, Boarbi S, Wang XM, Denis O, Braibant M, Pethe K, Locht C, Huygen K, Content J. Mycobacterium tuberculosis with disruption in genes encoding the phosphate binding proteins PstS1 and PstS2 is deficient in phosphate uptake and demonstrates reduced in vivo virulence. Infect Immun 2005; 73:1898-902. [PMID: 15731097 PMCID: PMC1064925 DOI: 10.1128/iai.73.3.1898-1902.2005] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By measuring phosphate uptake by Mycobacterium tuberculosis strains with the pstS1 and pstS2 genes genetically inactivated, we showed that these pstS genes encode high-affinity phosphate binding proteins. In a mouse infection model, both mutants were attenuated in virulence, suggesting that M. tuberculosis encounters limiting phosphate concentrations during its intracellular life span.
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Affiliation(s)
- Priska Peirs
- Pasteur Institute of Brussels, Engelandstraat 642, B-1180-Brussels, Belgium
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45
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Gupta S, Chakraborti PK, Sarkar D. Nucleotide-induced conformational change in the catalytic subunit of the phosphate-specific transporter from M. tuberculosis: implications for the ATPase structure. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1750:112-21. [PMID: 15936994 DOI: 10.1016/j.bbapap.2005.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2004] [Revised: 01/18/2005] [Accepted: 02/08/2005] [Indexed: 01/30/2023]
Abstract
The nucleotide binding subunit of the phosphate-specific transporter (PstB) from Mycobacterium tuberculosis is a member of the ABC family of permeases, which provides energy for transport through ATP hydrolysis. We utilized the intrinsic fluorescence of the single tryptophan containing protein to study the structural and conformational changes that occur upon nucleotide binding. ATP binding appeared to lead to a conformation in which the tryptophan residue had a higher degree of solvent exposure and fluorescence quenching. Substantial alteration in the proteolysis profile of PstB owing to nucleotide binding was used to decipher conformational change in the protein. In limited proteolysis experiments, we found that ATP or its nonhydrolyzable analog provided significant protection of the native protein, indicating that the effect of nucleotide on PstB conformation is directly associated with nucleotide binding. Taken together, these results indicate that nucleotide binding to PstB is accompanied by a global conformational change of the protein, which involves the helical domain from Arg137 to Trp150. Results reported here provide evidence that the putative movement of the alpha-helical sub-domain relative to the core sub-domain, until now only inferred from X-ray structures and modeling, is indeed a physiological phenomenon and is nucleotide dependent.
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Affiliation(s)
- Sankalp Gupta
- Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
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46
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Liu J, Lou Y, Yokota H, Adams PD, Kim R, Kim SH. Crystal structure of a PhoU protein homologue: a new class of metalloprotein containing multinuclear iron clusters. J Biol Chem 2005; 280:15960-6. [PMID: 15716271 DOI: 10.1074/jbc.m414117200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PhoU proteins are known to play a role in the regulation of phosphate uptake. In Thermotoga maritima, two PhoU homologues have been identified bioinformatically. Here we report the crystal structure of one of the PhoU homologues at 2.0 A resolution. The structure of the PhoU protein homologue contains a highly symmetric new structural fold composed of two repeats of a three-helix bundle. The structure unexpectedly revealed a trinuclear and a tetranuclear iron cluster that were found to be bound on the surface. Each of the two multinuclear iron clusters is coordinated by a conserved E(D)XXXD motif pair. Our structure reveals a new class of metalloprotein containing multinuclear iron clusters. The possible functional implication based on the structure are discussed.
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Affiliation(s)
- Jinyu Liu
- Berkeley Structural Genomics Center, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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47
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White AK, Metcalf WW. The htx and ptx operons of Pseudomonas stutzeri WM88 are new members of the pho regulon. J Bacteriol 2004; 186:5876-82. [PMID: 15317793 PMCID: PMC516845 DOI: 10.1128/jb.186.17.5876-5882.2004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The htx and ptx operons of Pseudomonas stutzeri WM88 allow for the use of the inorganic reduced phosphorus (P) compounds hypophosphite (P valence, +1) and phosphite (P valence, +3) as sole P sources. To support the proposed in vivo role for the htx and ptx operons, namely the use of phosphite and hypophosphite as alternative P sources, we used reporter gene fusions to examine their expression levels with respect to various P conditions. Expression of the htx and ptx operons was induced up to 17- and 22-fold, respectively, in cultures grown under phosphate starvation conditions relative to expression in medium with excess phosphate (Pi). However, the presence of the reduced P substrate hypophosphite, phosphite, or methylphosphonate, in addition to excess Pi, did not result in an increase in the expression of either operon. To provide further support for a role of the htx and ptx operons in Pi acquisition, we identified P. stutzeri phoBR homologs and constructed deletion mutants. Induction of the htx and ptx reporter gene fusions in response to growth on limiting Pi was abolished in DeltaphoB, DeltaphoR, and DeltaphoBR mutants, demonstrating that htx and ptx expression is phoBR dependent. The putative LysR-type regulator encoded by ptxE has no apparent role in the expression of the htx and ptx operons, as no effect was observed on the level of induction of either operon in a DeltaptxE mutant.
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Affiliation(s)
- Andrea K White
- Department of Microbiology, University of Illinois, B103 Chemical and Life Sciences Laboratory, 601 S. Goodwin Ave., Urbana, IL 61801, USA
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48
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Cánovas D, Mukhopadhyay R, Rosen BP, de Lorenzo V. Arsenate transport and reduction in the hyper-tolerant fungus Aspergillus sp. P37. Environ Microbiol 2003; 5:1087-93. [PMID: 14641588 DOI: 10.1046/j.1462-2920.2003.00508.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aspergillus sp. P37 is able to grow at arsenate concentrations of 0.2 M--more than 20-fold higher than that withstood by reference microorganisms such Escherichia coli, Saccharomyces cerevisiae and Aspergillus nidulans. This paper examines the transport of arsenate and phosphate and the reduction of arsenate in Aspergillus sp. P37. These properties were compared with the corresponding properties of the archetype strain Aspergillus nidulans TS1. Both uptake and efflux of arsenate were inhibited by carbonyl cyanide-p-trifluoromethoxyphenylhydrazone, suggesting that the transport system(s) is(are) membrane-potential dependent. As uptake of arsenate and phosphate are higher in Aspergillus sp. P37 than in A. nidulans, the increase in arsenate resistance cannot be accounted for by a change in uptake. Cells of both strains loaded with arsenic slowly released the oxyanion. Speciation of the arsenic in the medium showed an enhanced level of arsenate reduction in Aspergillus sp. P37. These data suggest that increased arsenate reduction is at least in part responsible for the hyper-tolerant phenotype of this fungus.
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Affiliation(s)
- David Cánovas
- Centro Nacional de Biotecnología-CSIC, Campus UAM-Cantoblanco, Madrid 28049, Spain
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49
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Auesukaree C, Homma T, Kaneko Y, Harashima S. Transcriptional regulation of phosphate-responsive genes in low-affinity phosphate-transporter-defective mutants in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2003; 306:843-50. [PMID: 12821119 DOI: 10.1016/s0006-291x(03)01068-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In Saccharomyces cerevisiae, two systems have been shown to be involved in the active transport of inorganic phosphate (P(i)) across the plasma membrane, the high-affinity system and the low-affinity system. The high-affinity system consists of Pho84p and Pho89p. The low-affinity system has recently been shown to be composed of Pho87p, Pho90p, and Pho91p. In this study, we found that the Deltapho87Deltapho90Deltapho91 strain which shows repressed PHO5 expression under high-P(i) condition has, unlike the wild-type strain, increased levels of PHO5 expression at an intermediate P(i) concentration of 0.5mM, whereas it is not defective in terms of P(i) uptake under the same conditions. Moreover, we observed that the transcription levels of PHO84 and PHO89 are also increased in low-affinity P(i)-transporter-defective mutants, indicating that the inactivation of low-affinity P(i) transporters leads to the activation of the PHO pathway. In contrast to that of PHO5, PHO84, and PHO89, the transcription of PHO87, PHO90, and PHO91 genes is independent of P(i) concentration and Pho4p activity, and the increased expression level of these transporters does not occur when other transporters including PHO84 are inactivated. The fact that low-affinity P(i)-transporter-defective mutants exhibit a derepression of P(i)-responsive genes suggests that low-affinity transporters play a role not only in P(i) transport but also in the regulation of the P(i) signal transduction pathway.
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Affiliation(s)
- Choowong Auesukaree
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Matsuzaki M, Abe M, Hara S, Iwasaki Y, Yamamoto I, Satoh T. An abundant periplasmic protein of the denitrifying phototroph Rhodobacter sphaeroides f. sp. denitrificans is PstS, a component of an ABC phosphate transport system. PLANT & CELL PHYSIOLOGY 2003; 44:212-216. [PMID: 12610226 DOI: 10.1093/pcp/pcg021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To understand a physiological role of an abundant 34-kDa periplasmic protein in the denitrifying phototroph Rhodobacter sphaeroides f. sp. denitrificans grown in a medium containing malate as the carbon source, the gene for the protein was isolated. The deduced amino acid sequence of the protein had a sequence similarity of 66.2% to that of PstS from Sinorhizobium meliloti. The downstream sequence of the Rhodobacter pstS contained five genes similar to pstCAB and phoUB, and its upstream sequence contained a putative regulatory sequence that is analogous to the Pho box involved in phosphate-limitation-induced gene expression in Escherichia coli. Both the amount of the PstS and the pstS promoter-driven expression of lacZ activity increased about two-fold in response to phosphate limitation. This is the first isolation of pst genes encoding proteins of an ABC phosphate transporter system from phototrophic bacteria.
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Affiliation(s)
- Masahiro Matsuzaki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, 739-8526 Japan.
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