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Huang W, Wang D, Zhang XX, Zhao M, Sun L, Zhou Y, Guan X, Xie Z. Regulatory roles of the second messenger c-di-GMP in beneficial plant-bacteria interactions. Microbiol Res 2024; 285:127748. [PMID: 38735241 DOI: 10.1016/j.micres.2024.127748] [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: 10/11/2023] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/14/2024]
Abstract
The rhizosphere system of plants hosts a diverse consortium of bacteria that confer beneficial effects on plant, such as plant growth-promoting rhizobacteria (PGPR), biocontrol agents with disease-suppression activities, and symbiotic nitrogen fixing bacteria with the formation of root nodule. Efficient colonization in planta is of fundamental importance for promoting of these beneficial activities. However, the process of root colonization is complex, consisting of multiple stages, including chemotaxis, adhesion, aggregation, and biofilm formation. The secondary messenger, c-di-GMP (cyclic bis-(3'-5') dimeric guanosine monophosphate), plays a key regulatory role in a variety of physiological processes. This paper reviews recent progress on the actions of c-di-GMP in plant beneficial bacteria, with a specific focus on its role in chemotaxis, biofilm formation, and nodulation.
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Affiliation(s)
- Weiwei Huang
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China
| | - Dandan Wang
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China
| | - Xue-Xian Zhang
- School of Natural Sciences, Massey University at Albany, Auckland 0745, New Zealand
| | - Mengguang Zhao
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China
| | - Li Sun
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China
| | - Yanan Zhou
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China
| | - Xin Guan
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China
| | - Zhihong Xie
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong Province 271018, China.
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Sun L, Wang D, Liu X, Zhou Y, Huang W, Guan X, Zhang X, Xie Z. The volatile organic compound acetoin enhances the colonization of Azorhizobium caulinodans ORS571 on Sesbania rostrata. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169006. [PMID: 38040356 DOI: 10.1016/j.scitotenv.2023.169006] [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: 10/04/2023] [Revised: 11/23/2023] [Accepted: 11/28/2023] [Indexed: 12/03/2023]
Abstract
Chemoreceptors play a crucial role in assisting bacterial sensing and response to environmental stimuli. Genome analysis of Azorhizobium caulinodans ORS571 revealed the presence of 43 putative chemoreceptors, but their biological functions remain largely unknown. In this study, we identified the chemoreceptor AmaP (methyl-accepting protein of A. caulinodans), characterized by the presence of the CHASE3 domain and exhibited a notable response to acetoin. Thus, we investigated the effect of acetoin sensing on its symbiotic association with the host. Our findings uncovered a compelling role for acetoin as a key player in enhancing various facets of A. caulinodans ORS571's performance including biofilm formation, colonization, and nodulation abilities. Notably, acetoin bolstered A. caulinodans ORS571's efficacy in promoting the growth of S. rostrata, even under moderate salt stress conditions. This study not only broadens our understanding of the AmaP protein with its distinctive CHASE3 domain but also highlights the promising potential of acetoin in fortifying the symbiotic relationship between A. caulinodans and Sesbania rostrata.
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Affiliation(s)
- Li Sun
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China
| | - Dandan Wang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China
| | - Xiaolin Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Yanan Zhou
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China
| | - Weiwei Huang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China
| | - Xin Guan
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China
| | - Xuexian Zhang
- School of Natural Sciences, Massey University at Albany, Auckland 0745, New Zealand
| | - Zhihong Xie
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian 271018, China.
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Cheng Y, Narayanan M, Shi X, Chen X, Li Z, Ma Y. Phosphate-solubilizing bacteria: Their agroecological function and optimistic application for enhancing agro-productivity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 901:166468. [PMID: 37619729 DOI: 10.1016/j.scitotenv.2023.166468] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 07/11/2023] [Accepted: 08/19/2023] [Indexed: 08/26/2023]
Abstract
Phosphorus (P) is a limiting nutrient in the soil-plant nutrient cycling. Although the exogenous application of chemical P fertilizers can satisfy crop P requirements during critical growth phases. While excessive P fertilizers use results in low phosphorus acquisition efficiency (PAE), it has serious environmental consequences and hastens the depletion of P mineral reserves. Phosphate-solubilizing bacteria (PSB) have the potential to make insoluble phosphate available to plants through solubilization and mineralization, increasing crop yields while maintaining environmental sustainability. Existing reviews mainly focus on the beneficial effects of PSB on crop performance and related mechanisms, while few of them elucidate the action mechanisms of PSB in soil-microbe-plant interactions for crop cultivation with high yield efficiency. Hence, this study provides a comprehensive review of the physicochemical and molecular mechanisms (e.g., root exudates, extracellular polysaccharides, organic acids, phosphatases, and phosphate-specific transport systems) of PSB to facilitate the P cycle in the soil-plant systems. Further, the potential of commercial applications of PSB (e.g., genetic engineering, seed priming and coating) are also discussed in order to highlight their contribution to sustainable agriculture. Finally, existing challenges and future prospects in agricultural applications are proposed. In conclusion, we firmly believe that PSB represent a highly significant biotechnological tool for enhancing agricultural productivity and offers a wide range of extensive potential applications.
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Affiliation(s)
- Yingying Cheng
- College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Mathiyazhagan Narayanan
- Division of Research and Innovation, Department of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Science, Chennai 602105, Tamil Nadu, India
| | - Xiaojun Shi
- College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Xinping Chen
- College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Zhenlun Li
- College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Ying Ma
- College of Resources and Environment, Southwest University, Chongqing 400716, China.
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Liu Y, Liu X, Dong X, Yin Z, Xie Z, Luo Y. Systematic Analysis of Lysine Acetylation Reveals Diverse Functions in Azorhizobium caulinodans Strain ORS571. Microbiol Spectr 2023; 11:e0353922. [PMID: 36475778 PMCID: PMC9927263 DOI: 10.1128/spectrum.03539-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 11/11/2022] [Indexed: 12/13/2022] Open
Abstract
Protein acetylation can quickly modify the physiology of bacteria to respond to changes in environmental or nutritional conditions, but little information on these modifications is available in rhizobia. In this study, we report the lysine acetylome of Azorhizobium caulinodans strain ORS571, a model rhizobium isolated from stem nodules of the tropical legume Sesbania rostrata that is capable of fixing nitrogen in the free-living state and during symbiosis. Antibody enrichment and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis were used to characterize the acetylome. There are 2,302 acetylation sites from 982 proteins, accounting for 20.8% of the total proteins. Analysis of the acetylated motifs showed the preferences for the amino acid residues around acetylated lysines. The response regulator CheY1, previously characterized to be involved in chemotaxis in strain ORS571, was identified as an acetylated protein, and a mutation of the acetylated site of CheY1 significantly impaired the strain's motility. In addition, a Zn+-dependent deacetylase (AZC_0414) was characterized, and the construction of a deletion mutant strain showed that it played a role in chemotaxis. Our study provides the first global analysis of lysine acetylation in ORS571, suggesting that acetylation plays a role in various physiological processes. In addition, we demonstrate its involvement in the chemotaxis process. The acetylome of ORS571 provides insights to investigate the regulation mechanism of rhizobial physiology. IMPORTANCE Acetylation is an important modification that regulates protein function and has been found to regulate physiological processes in various bacteria. The physiology of rhizobium A. caulinodans ORS571 is regulated by multiple mechanisms both when free living and in symbiosis with the host; however, the regulatory role of acetylation is not yet known. Here, we took an acetylome-wide approach to identify acetylated proteins in A. caulinodans ORS571 and performed clustering analyses. Acetylation of chemotaxis proteins was preliminarily investigated, and the upstream acetylation-regulating enzyme involved in chemotaxis was characterized. These findings provide new insights to explore the physiological mechanisms of rhizobia.
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Affiliation(s)
- Yanan Liu
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaolin Liu
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Xiaoyan Dong
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Zhiqiu Yin
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Zhihong Xie
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Yongming Luo
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
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Chaudhary P, Agri U, Chaudhary A, Kumar A, Kumar G. Endophytes and their potential in biotic stress management and crop production. Front Microbiol 2022; 13:933017. [PMID: 36325026 PMCID: PMC9618965 DOI: 10.3389/fmicb.2022.933017] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 09/12/2022] [Indexed: 11/21/2022] Open
Abstract
Biotic stress is caused by harmful microbes that prevent plants from growing normally and also having numerous negative effects on agriculture crops globally. Many biotic factors such as bacteria, fungi, virus, weeds, insects, and nematodes are the major constrains of stress that tends to increase the reactive oxygen species that affect the physiological and molecular functioning of plants and also led to the decrease in crop productivity. Bacterial and fungal endophytes are the solution to overcome the tasks faced with conventional farming, and these are environment friendly microbial commodities that colonize in plant tissues without causing any damage. Endophytes play an important role in host fitness, uptake of nutrients, synthesis of phytohormone and diminish the injury triggered by pathogens via antibiosis, production of lytic enzymes, secondary metabolites, and hormone activation. They are also reported to help plants in coping with biotic stress, improving crops and soil health, respectively. Therefore, usage of endophytes as biofertilizers and biocontrol agent have developed an eco-friendly substitute to destructive chemicals for plant development and also in mitigation of biotic stress. Thus, this review highlighted the potential role of endophytes as biofertilizers, biocontrol agent, and in mitigation of biotic stress for maintenance of plant development and soil health for sustainable agriculture.
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Affiliation(s)
- Parul Chaudhary
- Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
| | - Upasana Agri
- Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
| | | | - Ashish Kumar
- Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
| | - Govind Kumar
- Indian Council of Agricultural Research (ICAR)-Central Institute for Subtropical Horticulture, Lucknow, India
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Comparative Genomics Insights into a Novel Biocontrol Agent Paenibacillus peoriae Strain ZF390 against Bacterial Soft Rot. BIOLOGY 2022; 11:biology11081172. [PMID: 36009799 PMCID: PMC9404902 DOI: 10.3390/biology11081172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/27/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022]
Abstract
Simple Summary Bacterial soft rot, attributed to Pectobacterium brasiliense infection, has caused destructive impacts and colossal economic losses to China’s agricultural industry. Chemical control, which was ubiquitously used, cannot manage this disease as expected, so biocontrol has been followed with interest to date. In this study, we found a Paenibacillus peoriae strain ZF390 that had a potent control efficiency over cucumber plants against Pectobacterium brasiliense, and the comparative genomic analysis revealed biocontrol mechanisms might be involved in the strain ZF390. Abstract Bacterial soft rot, caused by Pectobacterium brasiliense, can infect several economically important horticultural crops. However, the management strategies available to control this disease are limited. Plant-growth-promoting rhizobacteria (PGPR) have been considered to be promising biocontrol agents. With the aim of obtaining a strain suitable for agricultural applications, 161 strains were isolated from the rhizosphere soil of healthy cucumber plants and screened through plate bioassays and greenhouse tests. Paenibacillus peoriae ZF390 exhibited an eminent control effect against soft rot disease and a broad antagonistic activity spectrum in vitro. Moreover, ZF390 showed good activities of cellulase, protease, and phosphatase and a tolerance of heavy metal. Whole-genome sequencing was performed and annotated to explore the underlying biocontrol mechanisms. Strain ZF390 consists of one 6,193,667 bp circular chromosome and three plasmids. Comparative genome analysis revealed that ZF390 involves ten gene clusters responsible for secondary metabolite antibiotic synthesis, matching its excellent biocontrol activity. Plenty of genes related to plant growth promotion, biofilm formation, and induced systemic resistance were mined to reveal the biocontrol mechanisms that might consist in strain ZF390. Overall, these findings suggest that strain ZF390 could be a potential biocontrol agent in bacterial-soft-rot management, as well as a source of antimicrobial mechanisms for further exploitation.
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Zhang J, Li S, Wang N, Chen W, Feng X, Jia B, Zhao Y, Yang T, Zong X. The introduced strain Mesorhizobium ciceri USDA3378 is more competitive than an indigenous strain in nodulation of chickpea in newly introduced areas of China. Lett Appl Microbiol 2022; 75:1171-1181. [PMID: 35793390 DOI: 10.1111/lam.13785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 11/30/2022]
Abstract
The present study aimed to compare the competitive advantage of two chickpea nodulating rhizobia strains (an indigenous strain Mesorhizobium muleiense CCBAU 83963T and an introduced strain Mesorhizobium ciceri USDA 3378) in different soils originated from new chickpea cultivation areas of China. The results showed that USDA 3378 had a significant competitive advantage in nodulation, with nodulation occupation rates ranging from 84.6% to 100% in all the sampled soils. According to the efficiency of symbiosis under single inoculation, chickpea plants inoculated with USDA 3378 showed better symbiotic performance based on the plant dry weight, leaf chlorophyll content and nodule numbers. The chickpea plants inoculated with USDA 3378 formed nodules about 2 days earlier than those inoculated with CCBAU 83963T . The higher growth in media and the stronger adsorption on chickpea roots of USDA 3378 when mixed with CCBAU 83963T may explain why USDA3378 shows a competitive advantage. The results from this study will contribute towards the development of effective chickpea rhizobial inoculants for soil conditioning and more environmentally friendly production of chickpeas in China.
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Affiliation(s)
- Junjie Zhang
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou, Henan Province, 450000, P. R. China.,Collaborative Innovation Center for Food Production and Safety of Henan Province, Zhengzhou, 450002, Henan Province, P. R. China
| | - Shuo Li
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou, Henan Province, 450000, P. R. China
| | - Nan Wang
- College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou, Henan Province, 450000, P. R. China
| | - Wenfeng Chen
- State Key Laboratory of Agrobiotechnology, Beijing 100193, China; College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, 100193, P. R. China
| | - Xin Feng
- Xinjiang Tianshan Qidou Biotechnology Co., Ltd., Urumqi, 830000, P. R. China
| | - Bingqi Jia
- Henan Fuyunwang Happy Farm Ecological Food Co., Ltd., Jia County, 467000, P. R. China
| | - Yongfeng Zhao
- Guyuan Branch of Ningxia Academy of Agriculture and Forestry Sciences, Guyuan, 756000, P. R. China
| | - Tao Yang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Bejing, 100081, P. R. China
| | - Xuxiao Zong
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Bejing, 100081, P. R. China
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Rani S, Kumar P, Dahiya P, Maheshwari R, Dang AS, Suneja P. Endophytism: A Multidimensional Approach to Plant-Prokaryotic Microbe Interaction. Front Microbiol 2022; 13:861235. [PMID: 35633681 PMCID: PMC9135327 DOI: 10.3389/fmicb.2022.861235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/11/2022] [Indexed: 11/20/2022] Open
Abstract
Plant growth and development are positively regulated by the endophytic microbiome via both direct and indirect perspectives. Endophytes use phytohormone production to promote plant health along with other added benefits such as nutrient acquisition, nitrogen fixation, and survival under abiotic and biotic stress conditions. The ability of endophytes to penetrate the plant tissues, reside and interact with the host in multiple ways makes them unique. The common assumption that these endophytes interact with plants in a similar manner as the rhizospheric bacteria is a deterring factor to go deeper into their study, and more focus was on symbiotic associations and plant–pathogen reactions. The current focus has shifted on the complexity of relationships between host plants and their endophytic counterparts. It would be gripping to inspect how endophytes influence host gene expression and can be utilized to climb the ladder of “Sustainable agriculture.” Advancements in various molecular techniques have provided an impetus to elucidate the complexity of endophytic microbiome. The present review is focused on canvassing different aspects concerned with the multidimensional interaction of endophytes with plants along with their application.
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Affiliation(s)
- Simran Rani
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Pradeep Kumar
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Priyanka Dahiya
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Rajat Maheshwari
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Amita Suneja Dang
- Centre for Medical Biotechnology, Maharshi Dayanand University, Rohtak, India
| | - Pooja Suneja
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
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Sun L, Cheng L, Ma Y, Lei P, Wang R, Gu Y, Li S, Zhang F, Xu H. Exopolysaccharides from Pantoea alhagi NX-11 specifically improve its root colonization and rice salt resistance. Int J Biol Macromol 2022; 209:396-404. [PMID: 35413311 DOI: 10.1016/j.ijbiomac.2022.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 12/13/2022]
Abstract
Plant growth-promoting rhizobacteria (PGPR) and their extracellular polymers such as exopolysaccharides can enhance rice salt stress resistance, however, the relevant mechanism remains unclear. In this study, an exopolysaccharides-deficient strain, named ΔpspD, was obtained from Pantoea alhagi NX-11 by chromosomal pspD deletion. The yield and characteristics of ΔpspD exopolysaccharides was obviously different from P. alhagi NX-11 exopolysaccharides (PAPS). Subsequently, hydroponic experiments showed that NX-11 or PAPS could enhance rice salt tolerance, but ΔpspD could not. Furthermore, it was found that PAPS promoted P. alhagi rhizosphere colonization through a direct effect on biofilm formation, as well as through an indirect impact of enhancing the abilities of biofilm formation and chemotaxis by altering rice root exudates. Importantly, the effect of PAPS in promoting the root colonization of NX-11 was specific. Through transcriptome and RT-qPCR analysis, we revealed that this specificity correlated with PAPS-induced lectin overexpression. The specificity between exopolysaccharides and the host microorganism ensures the colonization of the latter, and prevents other microorganisms from hitchhiking to the rice roots.
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Affiliation(s)
- Liang Sun
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Lifangyu Cheng
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Yuhang Ma
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Peng Lei
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| | - Rui Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Yian Gu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| | - Sha Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Fuhai Zhang
- Agricultural and Rural Bureau of Yantai, Yantai 264000, China
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
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10
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Gene Analysis of Listeria monocytogenes Suspended Aggregates Induced by Ralstonia insidiosa Cell-Free Supernatants under Nutrient-Poor Environments. Microorganisms 2021; 9:microorganisms9122591. [PMID: 34946191 PMCID: PMC8704912 DOI: 10.3390/microorganisms9122591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 01/08/2023] Open
Abstract
Listeria monocytogenes is a zoonotic food-borne pathogen. The production of food-borne pathogenic bacteria aggregates is considered to be a way to improve their resistance and persistence in the food chain. Ralstonia insidiosa has been shown to induce L. monocytogenes to form suspended aggregates, but induction mechanisms remain unclear. In the study, the effect of R. insidiosa cell-free supernatants cultured in 10% TSB medium (10% RIS) on the formation of L. monocytogenes suspended aggregates was evaluated. Next, the Illumina RNA sequencing was used to compare the transcriptional profiles of L. monocytogenes in 10% TSB medium with and without 10% RIS to identify differentially expressed genes (DEGs). The result of functional annotation analysis of DEGs indicated that these genes mainly participate in two component system, bacterial chemotaxis and flagellar assembly. Then the reaction network of L. monocytogenes suspended aggregates with the presence of 10% RIS was summarized. The gene-deletion strain of L. monocytogenes was constructed by homologous recombination. The result showed that cheA and cheY are key genes in the formation of suspended aggregates. This research is the preliminary verification of suspended aggregates’ RNA sequencing and is helpful to analyze the aggregation mechanisms of food-borne pathogenic bacteria from a new perspective.
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Sun L, Wang D, Yin Z, Zhang C, Bible A, Xie Z. The FtcR-Like Protein ActR in Azorhizobium caulinodans ORS571 Is Involved in Bacterial Motility and Symbiosis With the Host Plant. Front Microbiol 2021; 12:744268. [PMID: 34867860 PMCID: PMC8639532 DOI: 10.3389/fmicb.2021.744268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/20/2021] [Indexed: 12/22/2022] Open
Abstract
Bacterial signal transduction pathways are important for a variety of adaptive responses to environment, such as two-component systems (TCSs). In this paper, we reported the characterization of a transcriptional regulator in Azorhizobium caulinodans ORS571, ActR, with an N-terminal receiver domain and one C-terminal OmpR/PhoB-type DNA binding domain. Sequence analysis showed that ActR shared a high similarity with FtcR regulator of Brucella melitensis 16M known to be involved in flagellar regulation. The structural gene of this regulator was largely distributed in Alphaproteobacteria, in particular in Rhizobiales and Rhodobacterales, and was located within clusters of genes related to motility functions. Furthermore, we studied the biological function of ActR in A. caulinodans grown at the free-living state or in association with Sesbania rostrata by constructing actR gene deletion mutant. In the free-living state, the bacterial flagellum and motility ability were entirely deleted, the expression of flagellar genes was downregulated; and the exopolysaccharide production, biofilm formation, and cell flocculation decreased significantly compared with those of the wild-type strain. In the symbiotic state, ΔactR mutant strain showed weakly competitive colonization and nodulation on the host plant. These results illustrated that FtcR-like regulator in A. caulinodans is involved in flagellar biosynthesis and provide bacteria with an effective competitive nodulation for symbiosis. These findings improved our knowledge of FtcR-like transcriptional regulator in A. caulinodans.
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Affiliation(s)
- Li Sun
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Dandan Wang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Zhiqiu Yin
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Chengsheng Zhang
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Amber Bible
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Zhihong Xie
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China.,Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
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12
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Azorhizobium caulinodans chemotaxis is controlled by an unusual phosphorelay network. J Bacteriol 2021; 204:e0052721. [PMID: 34843377 DOI: 10.1128/jb.00527-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Azorhizobium caulinodans is a nitrogen-fixing bacterium that forms root nodules on its host legume, Sesbania rostrata. This agriculturally significant symbiotic relationship is important in lowland rice cultivation, and allows for nitrogen fixation under flood conditions. Chemotaxis plays an important role in bacterial colonization of the rhizosphere. Plant roots release chemical compounds that are sensed by bacteria, triggering chemotaxis along a concentration gradient toward the roots. This gives motile bacteria a significant competitive advantage during root surface colonization. Although plant-associated bacterial genomes often encode multiple chemotaxis systems, A. caulinodans appears to encode only one. The che cluster on the A. caulinodans genome contains cheA, cheW, cheY2, cheB, and cheR. Two other chemotaxis genes, cheY1 and cheZ, are located independently from the che operon. Both CheY1 and CheY2 are involved in chemotaxis, with CheY1 being the predominant signaling protein. A. caulinodans CheA contains an unusual set of C-terminal domains: a CheW-like/Receiver pair (termed W2-Rec), follows the more common single CheW-like domain. W2-Rec impacts both chemotaxis and CheA function. We found a preference for transfer of phosphoryl groups from CheA to CheY2, rather than to W2-Rec or CheY1, which appears to be involved in flagellar motor binding. Furthermore, we observed increased phosphoryl group stabilities on CheY1 compared to CheY2 or W2-Rec. Finally, CheZ enhanced dephosphorylation of CheY2 substantially more than CheY1, but had no effect on the dephosphorylation rate of W2-Rec. This network of phosphotransfer reactions highlights a previously uncharacterized scheme for regulation of chemotactic responses. IMPORTANCE Chemotaxis allows bacteria to move towards nutrients and away from toxins in their environment. Chemotactic movement provides a competitive advantage over non-specific motion. CheY is an essential mediator of the chemotactic response with phosphorylated and unphosphorylated forms of CheY differentially interacting with the flagellar motor to change swimming behavior. Previously established schemes of CheY dephosphorylation include action of a phosphatase and/or transfer of the phosphoryl group to another receiver domain that acts as a sink. Here, we propose A. caulinodans uses a concerted mechanism in which the Hpt domain of CheA, CheY2, and CheZ function together as a dual sink system to rapidly reset chemotactic signaling. To the best of our knowledge, this mechanism is unlike any that have previously been evaluated. Chemotaxis systems that utilize both receiver and Hpt domains as phosphate sinks likely occur in other bacterial species.
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Liu X, Liu Y, Wang Y, Wang D, Johnson KS, Xie Z. The Hypoxia-Associated Localization of Chemotaxis Protein CheZ in Azorhizorbium caulinodans. Front Microbiol 2021; 12:731419. [PMID: 34737727 PMCID: PMC8563088 DOI: 10.3389/fmicb.2021.731419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 09/22/2021] [Indexed: 11/15/2022] Open
Abstract
Spatial organization of chemotactic proteins is important for cooperative response to external stimuli. However, factors affecting the localization dynamics of chemotaxis proteins are less studied. According to some reports, the polar localization of chemotaxis system I is induced by hypoxia and starvation in Vibrio cholerae. However, in V. cholerae, the chemotaxis system I is not involved in flagellum-mediated chemotaxis, and it may play other alternative cellular functions. In this study, we found that the polar localization of CheZ, a phosphatase regulating chemotactic movement in Azorhizobium caulinodans ORS571, can also be affected by hypoxia and cellular energy-status. The conserved phosphatase active site D165 and the C-terminus of CheZ are essential for the energy-related localization, indicating a cross link between hypoxia-related localization changes and phosphatase activity of CheZ. Furthermore, three of five Aer-like chemoreceptors containing PAS domains participate in the cellular localization of CheZ. In contrast to carbon starvation, free-living nitrogen fixation can alleviate the role of nitrogen limitation and hypoxia on polar localization of CheZ. These results showed that the localization changes induced by hypoxia might be a strategy for bacteria to adapt to complex environment.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Yanan Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Yixuan Wang
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Dandan Wang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Kevin Scot Johnson
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Zhihong Xie
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
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14
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Liu W, Bai X, Li Y, Zhang H, Hu X. FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant. BMC Microbiol 2021; 21:80. [PMID: 33750295 PMCID: PMC7945327 DOI: 10.1186/s12866-021-02138-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 02/22/2021] [Indexed: 11/10/2022] Open
Abstract
Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-021-02138-w.
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Affiliation(s)
- Wei Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Xue Bai
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China
| | - Yan Li
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Haikun Zhang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Xiaoke Hu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China. .,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China. .,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.
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15
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Gumerov VM, Andrianova EP, Zhulin IB. Diversity of bacterial chemosensory systems. Curr Opin Microbiol 2021; 61:42-50. [PMID: 33684668 DOI: 10.1016/j.mib.2021.01.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/27/2021] [Accepted: 01/30/2021] [Indexed: 12/20/2022]
Abstract
Chemosensory system is the most complex, specialized mode of signal transduction in bacteria and archaea. It is composed of several core and auxiliary protein components that are highly organized in order to deliver a fast response to changing environmental conditions. Chemosensory pathways were studied in-depth in a handful of model organisms and experimentally characterized at least to some degree in approximately thirty other species. However, genome-wide analyses have revealed their presence in thousands of sequenced microbial genomes. Both experimental and computational studies uncovered substantial diversity in system design, functional regulation, cellular localization and phyletic distribution of chemosensory pathways. Here, we summarize advances and expose gaps in our current understanding of the diversity of chemosensory systems.
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Affiliation(s)
- Vadim M Gumerov
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210 USA
| | | | - Igor B Zhulin
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210 USA.
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16
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Aroney STN, Poole PS, Sánchez-Cañizares C. Rhizobial Chemotaxis and Motility Systems at Work in the Soil. FRONTIERS IN PLANT SCIENCE 2021; 12:725338. [PMID: 34512702 PMCID: PMC8429497 DOI: 10.3389/fpls.2021.725338] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/06/2021] [Indexed: 05/17/2023]
Abstract
Bacteria navigate their way often as individual cells through their chemical and biological environment in aqueous medium or across solid surfaces. They swim when starved or in response to physical and chemical stimuli. Flagella-driven chemotaxis in bacteria has emerged as a paradigm for both signal transduction and cellular decision-making. By altering motility, bacteria swim toward nutrient-rich environments, movement modulated by their chemotaxis systems with the addition of pili for surface movement. The numbers and types of chemoreceptors reflect the bacterial niche and lifestyle, with those adapted to complex environments having diverse metabolic capabilities, encoding far more chemoreceptors in their genomes. The Alpha-proteobacteria typify the latter case, with soil bacteria such as rhizobia, endosymbionts of legume plants, where motility and chemotaxis are essential for competitive symbiosis initiation, among other processes. This review describes the current knowledge of motility and chemotaxis in six model soil bacteria: Sinorhizobium meliloti, Agrobacterium fabacearum, Rhizobium leguminosarum, Azorhizobium caulinodans, Azospirillum brasilense, and Bradyrhizobium diazoefficiens. Although motility and chemotaxis systems have a conserved core, rhizobia possess several modifications that optimize their movements in soil and root surface environments. The soil provides a unique challenge for microbial mobility, since water pathways through particles are not always continuous, especially in drier conditions. The effectiveness of symbiont inoculants in a field context relies on their mobility and dispersal through the soil, often assisted by water percolation or macroorganism movement or networks. Thus, this review summarizes the factors that make it essential to consider and test rhizobial motility and chemotaxis for any potential inoculant.
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17
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Liu X, Liu Y, Johnson KS, Dong X, Xie Z. Protein Residues and a Novel Motif Involved in the Cellular Localization of CheZ in Azorhizobium caulinodans ORS571. Front Microbiol 2020; 11:585140. [PMID: 33365019 PMCID: PMC7750401 DOI: 10.3389/fmicb.2020.585140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 11/16/2020] [Indexed: 12/26/2022] Open
Abstract
Chemotaxis is essential for the competitiveness of motile bacteria in complex and harsh environments. The localization of chemotactic proteins in the cell is critical for coordinating a maximal response to chemotactic signals. One chemotaxis protein with a well-defined subcellular localization is the phosphatase CheZ. CheZ localizes to cell poles by binding with CheA in Escherichia coli and other enteric bacteria, or binding with a poorly understood protein called ChePep in epsilon-Proteobacteria. In alpha-Proteobacteria, CheZ lacks CheA-binding sites, and its cellular localization remains unknown. We therefore determined the localization of CheZ in the alpha-Proteobacteria Azorhizobium caulinodans ORS571. A. caulinodans CheZ, also termed as CheZAC, was found to be located to cell poles independently of CheA, and we suspect that either the N-terminal helix or the four-helix bundle of CheZAC is sufficient to locate to cell poles. We also found a novel motif, AXXFQ, which is adjacent to the phosphatase active motif DXXXQ, which effects the monopolar localization of CheZAC. This novel motif consisting of AXXFQ is conserved in CheZ and widely distributed among Proteobacteria. Finally, we found that the substitution of phosphatase active site affects the polar localization of CheZAC. In total, this work characterized the localization pattern of CheZ containing a novel motif, and we mapped the regions of CheZAC that are critical for its polar localization.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Yanan Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Kevin Scot Johnson
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Xiaoyan Dong
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Zhihong Xie
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
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18
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The phosphorylated regulator of chemotaxis is crucial throughout biofilm biogenesis in Shewanella oneidensis. NPJ Biofilms Microbiomes 2020; 6:54. [PMID: 33188190 PMCID: PMC7666153 DOI: 10.1038/s41522-020-00165-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/13/2020] [Indexed: 02/04/2023] Open
Abstract
The core of the chemotaxis system of Shewanella oneidensis is made of the CheA3 kinase and the CheY3 regulator. When appropriated, CheA3 phosphorylates CheY3, which, in turn, binds to the rotor of the flagellum to modify the swimming direction. In this study, we showed that phosphorylated CheY3 (CheY3-P) also plays an essential role during biogenesis of the solid-surface-associated biofilm (SSA-biofilm). Indeed, in a ΔcheY3 strain, the formation of this biofilm is abolished. Using the phospho-mimetic CheY3D56E mutant, we showed that CheY-P is required throughout the biogenesis of the biofilm but CheY3 phosphorylation is independent of CheA3 during this process. We have recently found that CheY3 interacts with two diguanylate cyclases (DGCs) and with MxdA, the c-di-GMP effector, probably triggering exopolysaccharide synthesis by the Mxd machinery. Here, we discovered two additional DGCs involved in SSA-biofilm development and showed that one of them interacts with CheY3. We therefore propose that CheY3-P acts together with DGCs to control SSA-biofilm formation. Interestingly, two orthologous CheY regulators complement the biofilm defect of a ΔcheY3 strain, supporting the idea that biofilm formation could involve CheY regulators in other bacteria.
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19
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Liu X, Zhang K, Liu Y, Zou D, Wang D, Xie Z. Effects of Calcium and Signal Sensing Systems on Azorhizobium caulinodans Biofilm Formation and Host Colonization. Front Microbiol 2020; 11:563367. [PMID: 33072026 PMCID: PMC7533552 DOI: 10.3389/fmicb.2020.563367] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/25/2020] [Indexed: 12/22/2022] Open
Abstract
Biofilm formation is important for establishing plants-microbe associations. The role of calcium on biofilm formation has been studied in many bacteria except rhizobia. In this study, we investigated the role of calcium for biofilm formation in Azorhizobium caulindans, which forms nodules in the stem and root of its host plant Sesbania rostrata. We found that calcium is essential for A. caulindans biofilm formation, in addition to the presence of extracellular matrix components, eDNA and proteins. Also, calcium-mediated biofilm formation was tested with chemotaxis, motility, cyclic di-GMP synthesis, and quorum sensing mutants. Finally, calcium was found to promote S. rostrata root colonization of A. caulinodans. In total, these results show that calcium is essential for A. caulindans biofilm formation, and it affects the interaction between A. caulinodans and host plant.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Kaiye Zhang
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yanan Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Desheng Zou
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Dandan Wang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Tai'an, China
| | - Zhihong Xie
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Tai'an, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
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20
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CheY1 and CheY2 of Azorhizobium caulinodans ORS571 Regulate Chemotaxis and Competitive Colonization with the Host Plant. Appl Environ Microbiol 2020; 86:AEM.00599-20. [PMID: 32471918 DOI: 10.1128/aem.00599-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/21/2020] [Indexed: 02/06/2023] Open
Abstract
The genome of Azorhizobium caulinodans ORS571 encodes two chemotaxis response regulators: CheY1 and CheY2. cheY1 is located in a chemotaxis cluster (cheAWY1BR), while cheY2 is located 37 kb upstream of the cheAWY1BR cluster. To determine the contributions of CheY1 and CheY2, we compared the wild type (WT) and mutants in the free-living state and in symbiosis with the host Sesbania rostrata Swim plate tests and capillary assays revealed that both CheY1 and CheY2 play roles in chemotaxis, with CheY2 having a more prominent role than CheY1. In an analysis of the swimming paths of free-swimming cells, the ΔcheY1 mutant exhibited decreased frequency of direction reversal, whereas the ΔcheY2 mutant appeared to change direction much more frequently than the WT. Exopolysaccharide (EPS) production in the ΔcheY1 and ΔcheY2 mutants was lower than that in the WT, but the ΔcheY2 mutant had more obvious EPS defects that were similar to those of the ΔcheY1 ΔcheY2 and Δeps1 mutants. During symbiosis, the levels of competitiveness for root colonization and nodule occupation of ΔcheY1 and ΔcheY2 mutants were impaired compared to those of the WT. Moreover, the competitive colonization ability of the ΔcheY2 mutant was severely impaired compared to that of the ΔcheY1 mutant. Taken together, the ΔcheY2 phenotypes are more severe than the ΔcheY1 phenotype in free-living and symbiotic states, and that of the double mutant resembles the ΔcheY2 single-mutant phenotype. These defects of ΔcheY1 and ΔcheY2 mutants were restored to the WT phenotype by complementation. These results suggest that there are different regulatory mechanisms of CheY1 and CheY2 and that CheY2 is a key chemotaxis regulator under free-living and symbiosis conditions.IMPORTANCE Azorhizobium caulinodans ORS571 is a motile soil bacterium that has the dual capacity to fix nitrogen both under free-living conditions and in symbiosis with Sesbania rostrata, forming nitrogen-fixing root and stem nodules. Bacterial chemotaxis to chemoattractants derived from host roots promotes infection and subsequent nodule formation by directing rhizobia to appropriate sites of infection. In this work, we identified and demonstrated that CheY2, a chemotactic response regulator encoded by a gene outside the chemotaxis cluster, is required for chemotaxis and multiple other cell phenotypes. CheY1, encoded by a gene in the chemotaxis cluster, also plays a role in chemotaxis. Two response regulators mediate bacterial chemotaxis and motility in different ways. This work extends the understanding of the role of multiple response regulators in Gram-negative bacteria.
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21
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Liu W, Li Y, Bai X, Wu H, Bian L, Hu X. LuxR-Type Regulator AclR1 of Azorhizobium caulinodans Regulates Cyclic di-GMP and Numerous Phenotypes in Free-Living and Symbiotic States. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:528-538. [PMID: 31789101 DOI: 10.1094/mpmi-10-19-0306-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
LuxR-type regulators play important roles in transcriptional regulation in bacteria and control various biological processes. A genome sequence analysis showed the existence of seven LuxR-type regulators in Azorhizobium caulinodans ORS571, an important nitrogen-fixing bacterium in both its free-living state and in symbiosis with its host, Sesbania rostrata. However, the functional mechanisms of these regulators remain unclear. In this study, we identified a LuxR-type regulator that contains a cheY-homologous receiver (REC) domain in its N terminus and designated it AclR1. Interestingly, phylogenetic analysis revealed that AclR1 exhibited relatively close evolutionary relationships with MalT/GerE/FixJ/NarL family proteins. Functional analysis of an aclR1 deletion mutant (ΔaclR1) in the free-living state showed that AclR1 positively regulated cell motility and flocculation but negatively regulated exopolysaccharide production, biofilm formation, and second messenger cyclic diguanylate (c-di-GMP)-related gene expression. In the symbiotic state, the ΔaclR1 mutant was defective in competitive colonization and nodulation on host plants. These results suggested that AclR1 could provide bacteria with the ability to compete effectively for symbiotic nodulation. Overall, our results show that the REC-LuxR-type regulator AclR1 regulates numerous phenotypes both in the free-living state and during host plant symbiosis.
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Affiliation(s)
- Wei Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Yan Li
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xue Bai
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Life Sciences, Yantai University, Yantai, China
| | - Haiguang Wu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Life Sciences, Yantai University, Yantai, China
| | - Lanxing Bian
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Life Sciences, Yantai University, Yantai, China
| | - Xiaoke Hu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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22
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Liu X, Zhang K, Liu Y, Xie Z, Zhang C. Oxalic Acid From Sesbania rostrata Seed Exudates Mediates the Chemotactic Response of Azorhizobium caulinodans ORS571 Using Multiple Strategies. Front Microbiol 2019; 10:2727. [PMID: 31849879 PMCID: PMC6901664 DOI: 10.3389/fmicb.2019.02727] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 11/08/2019] [Indexed: 12/14/2022] Open
Abstract
Chemotaxis toward seed exudates is important in the establishment of microbe-plant associations. The objective of this work was to explore whether organic acids from the seed exudates of Sesbania rostrata play a role in recruiting Azorhizobium caulinodans ORS571 in the plant rhizosphere. High-performance liquid chromatography (HPLC) was used to analyze the organic acid content in seed exudates of S. rostrata and to further determine their roles in A. caulinodans growth and chemotactic response. Succinic, acetic, citric, oxalic, and lactic acids were the most abundant, and, except for oxalic acid, they could support A. caulinodans growth as the sole carbon source. TlpA1, a transmembrane chemoreceptor, was found to be involved in the chemotactic response to these organic acids. Oxalic acid played a direct role in the chemotactic response, but it also played an indirect role by promoting or inhibiting the chemotactic response toward other chemoeffectors. Furthermore, the indirect role of oxalic acid on other chemoeffectors was concentration-dependent. The effect of oxalic acid at different concentrations on host root colonization was also determined. By using different strategies, oxalic acid appears to play a major role in the early steps of the association of A. caulinodans and its host plant.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Kaiye Zhang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Agriculture, Shanxi Agricultural University, Taigu, China
| | - Yanan Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Chengsheng Zhang
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
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23
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Liu X, Xie Z. Inactivation of the Phosphatase CheZ Alters Cell-Surface Properties of Azorhizobium caulinodans ORS571 and Symbiotic Association with Sesbania rostrata. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1547-1556. [PMID: 31287368 DOI: 10.1094/mpmi-05-19-0143-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Azorhizobium caulinodans can form root and stem nodules with the host plant Sesbania rostrata. The role of the CheZ phosphatase in the A. caulinodans chemotaxis pathway was previously explored using the nonchemotactic cheZ mutant strain (AC601). This mutant displayed stronger attachment to the root surface, enhancing early colonization; however, this did not result in increased nodulation efficiency. In this study, we further investigated the role of CheZ in the interaction between strain ORS571 and the roots of its host plant. By tracking long-term colonization dynamic of cheZ mutant marked with LacZ, we found a decrease of colonization of the cheZ mutant during this process. Furthermore, the cheZ mutant could not spread on the root surface freely and was gradually outcompeted by the wild type in original colonization sites. Quantitative reverse-transcription PCR analyses showed that exp genes encoding exopolysaccharides synthesis, including oac3, were highly expressed in the cheZ mutant. Construction of a strain carrying a deletion of both cheZ and oac3 resulted in a mutant strain defective in the colonization process to the same extent as found with the oac3 single-mutant strain. This result suggested that the enhanced colonization of the cheZ mutant may be achieved through regulating the formation of exopolysaccharides. This shows the importance of the chemotactic proteins in the interaction between rhizobia and host plants, and expands our understanding of the symbiosis interaction between rhizobium and host plant.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
- Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
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24
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Liu X, Xie Z, Wang Y, Sun Y, Dang X, Sun H. A Dual Role of Amino Acids from Sesbania rostrata Seed Exudates in the Chemotaxis Response of Azorhizobium caulinodans ORS571. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1134-1147. [PMID: 30920344 DOI: 10.1094/mpmi-03-19-0059-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Azorhizobium caulinodans ORS571 can induce nodule formation on the roots and the stems of its host legume, Sesbania rostrata. Plant exudates are essential in the dialogue between microbes and their host plant and, in particular, amino acids can play an important role in the chemotactic response of bacteria. Histidine, arginine, and aspartate, which are the three most abundant amino acids present in S. rostrata seed exudates, behave as chemoattractants toward A. caulinodans. A position-specific-iterated BLAST analysis of the methyl-accepting chemotaxis proteins (MCPs) (chemoreceptors) in the genome of A. caulinodans was performed. Among the 43 MCP homologs, two MCPs harboring a dCache domain were selected as possible cognate amino acid MCPs. After analysis of relative gene expression levels and construction of a gene-deleted mutant strain, one of them, AZC_0821 designed as TlpH, was confirmed to be responsible for the chemotactic response to the three amino acids. In addition, it was found that these three amino acids can also influence chemotaxis of A. caulinodans independently of the chemosensory receptors, by being involved in the increase of the expression level of several che and fla genes involved in the chemotaxis pathway and flagella synthesis. Thus, the contribution of amino acids present in seed exudates is directly related to the role as chemoattractants and indirectly related to the role in the regulation of expression of key genes involved in chemotaxis and motility. This "dual role" is likely to influence the formation of biofilms by A. caulinodans and the host root colonization properties of this bacterium.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
| | - Yixuan Wang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Yu Sun
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaoxiao Dang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Haishuan Sun
- Shandong Huibang Bohai Agriculture Development Limited Company, Dongying, People's Republic of China
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25
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The Two Chemotaxis Clusters in Caulobacter crescentus Play Different Roles in Chemotaxis and Biofilm Regulation. J Bacteriol 2019; 201:JB.00071-19. [PMID: 31109992 DOI: 10.1128/jb.00071-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/16/2019] [Indexed: 02/06/2023] Open
Abstract
The holdfast polysaccharide adhesin is crucial for irreversible cell adhesion and biofilm formation in Caulobacter crescentus Holdfast production is tightly controlled via developmental regulators, as well as via environmental and physical signals. Here, we identify a novel mode of regulation of holdfast synthesis that involves chemotaxis proteins. We characterized the two identified chemotaxis clusters of C. crescentus and showed that only the previously characterized major cluster is involved in the chemotactic response toward different carbon sources. However, both chemotaxis clusters encoded in the C. crescentus genome play a role in biofilm formation and holdfast production by regulating the expression of hfiA, the gene encoding the holdfast inhibitor HfiA. We show that CheA and CheB proteins act in an antagonistic manner, as follows: while the two CheA proteins negatively regulate hfiA expression, the CheB proteins are positive regulators, thus providing a modulation of holdfast synthesis and surface attachment.IMPORTANCE Chemosensory systems constitute major signal transduction pathways in bacteria. These systems are involved in chemotaxis and other cell responses to environment conditions, such as the production of adhesins to enable irreversible adhesion to a surface and surface colonization. The C. crescentus genome encodes two complete chemotaxis clusters. Here, we characterized the second novel chemotaxis-like cluster. While only the major chemotaxis cluster is involved in chemotaxis, both chemotaxis systems modulate C. crescentus adhesion by controlling expression of the holdfast synthesis inhibitor HfiA. Here, we identify a new level in holdfast regulation, providing new insights into the control of adhesin production that leads to the formation of biofilms in response to the environment.
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26
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Dang X, Xie Z, Liu W, Sun Y, Liu X, Zhu Y, Staehelin C. The genome of Ensifer alkalisoli YIC4027 provides insights for host specificity and environmental adaptations. BMC Genomics 2019; 20:643. [PMID: 31405380 PMCID: PMC6689892 DOI: 10.1186/s12864-019-6004-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 07/29/2019] [Indexed: 12/21/2022] Open
Abstract
Background Ensifer alkalisoli YIC4027, a recently characterized nitrogen-fixing bacterium of the genus Ensifer, has been isolated from root nodules of the host plant Sesbania cannabina. This plant is widely used as green manure and for soil remediation. E. alkalisoli YIC4027 can grow in saline-alkaline soils and is a narrow-host-range strain that establishes a symbiotic relationship with S. cannabina. The complete genome of this strain was sequenced to better understand the genetic basis of host specificity and adaptation to saline-alkaline soils. Results E. alkalisoli YIC4027 was found to possess a 6.1-Mb genome consisting of three circular replicons: one chromosome (3.7 Mb), a chromid (1.9 Mb) and a plasmid (0.46 Mb). Genome comparisons showed that strain YIC4027 is phylogenetically related to broad-host-range Ensifer fredii strains. Synteny analysis revealed a strong collinearity between chromosomes of E. alkalisoli YIC4027 and those of the E. fredii NGR234 (3.9 Mb), HH103 (4.3 Mb) and USDA257 (6.48 Mb) strains. Notable differences were found for genes required for biosynthesis of nodulation factors and protein secretion systems, suggesting a role of these genes in host-specific nodulation. In addition, the genome analysis led to the identification of YIC4027 genes that are presumably related to adaptation to saline-alkaline soils, rhizosphere colonization and nodulation competitiveness. Analysis of chemotaxis cluster genes and nodulation tests with constructed che gene mutants indicated a role of chemotaxis and flagella-mediated motility in the symbiotic association between YIC4027 and S. cannabina. Conclusions This study provides a basis for a better understanding of host specific nodulation and of adaptation to a saline-alkaline rhizosphere. This information offers the perspective to prepare optimal E. alkalisoli inocula for agriculture use and soil remediation. Electronic supplementary material The online version of this article (10.1186/s12864-019-6004-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiaoxiao Dang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,University of Chinese Academy of Sciences, Beijing, China.,Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China. .,Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China.
| | - Wei Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Yu Sun
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,University of Chinese Academy of Sciences, Beijing, China.,Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,University of Chinese Academy of Sciences, Beijing, China.,Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Yongqiang Zhu
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, 201203, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
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27
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Sun Y, Xie Z, Sui F, Liu X, Cheng W. Identification of Cbp1, a c-di-GMP Binding Chemoreceptor in Azorhizobium caulinodans ORS571 Involved in Chemotaxis and Nodulation of the Host Plant. Front Microbiol 2019; 10:638. [PMID: 31001223 PMCID: PMC6454048 DOI: 10.3389/fmicb.2019.00638] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/13/2019] [Indexed: 01/10/2023] Open
Abstract
Cbp1, a chemoreceptor containing a PilZ domain was identified in Azorhizobium caulinodans ORS571, a nitrogen-fixing free-living soil bacterium that induces nodule formation in both the roots and stems of the host legume Sesbania rostrata. Chemoreceptors are responsible for sensing signals in the chemotaxis pathway, which guides motile bacteria to beneficial niches and plays an important role in the establishment of rhizobia-legume symbiosis. PilZ domain proteins are known to bind the second messenger c-di-GMP, an important regulator of motility, biofilm formation and virulence. Cbp1 was shown to bind c-di-GMP through the conserved RxxxR motif of its PilZ domain. A mutant strain carrying a cbp1 deletion was impaired in chemotaxis, a feature that could be restored by genetic complementation. Compared with the wild type strain, the Δcbp1 mutant displayed enhanced aggregation and biofilm formation. The Δcbp1 mutant induced functional nodules when inoculated individually. However, the Δcbp1 mutant was less competitive than the wild type in competitive root colonization and nodulation. These data are in agreement with the hypothesis that the c-di-GMP binding chemoreceptor Cbp1 in A. caulinodans is involved in chemotaxis and nodulation.
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Affiliation(s)
- Yu Sun
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Fu Sui
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Wuzeng Cheng
- Shandong Huibang Bohai Agriculture Development Limited Company, Dongying, China
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28
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Abstract
Complex chemosensory systems control multiple biological functions in bacteria, such as chemotaxis, gene regulation, and cell cycle progression. Many species contain more than one chemosensory system per genome, but little is known about their potential interplay. In this study, we reveal cross talk between two chemosensory pathways that modulate chemotaxis and biofilm formation in Comamonas testosteroni We demonstrate that some chemoreceptors that govern chemotaxis also contribute to biofilm formation and these chemoreceptors can physically interact with components of both pathways. Finally, we show that the chemotaxis histidine kinase CheA can phosphorylate not only its cognate response regulator CheY2 but also one of the response regulators from the pathway mediating biofilm formation, FlmD. The phosphoryl group transfer from CheA to CheY2 is much faster than that from CheA to FlmD, which is consistent with chemotaxis being a fast response and biofilm formation being a much slower developmental process. We propose that cross talk between chemosensory pathways may play a role in coordination of complex behaviors in bacteria.IMPORTANCE In many bacteria, two or more homologous chemosensory pathways control several cellular functions, such as motility and gene regulation, in response to changes in the cell's microenvironment. Cross talk between signal transduction systems is poorly understood; while generally it is considered to be undesired, in some instances it might be beneficial for coregulation of complex behaviors. We demonstrate that several receptors from the pathway controlling motility can physically interact with downstream components of the pathway controlling biofilm formation. We further show that a kinase from the pathway controlling motility can also phosphorylate a response regulator from the pathway controlling biofilm formation. We propose that cross talk between two chemosensory pathways might be involved in coordination of two types of cell behavior-chemotaxis and biofilm formation.
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