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Li Y, Gao Y, Chen W, Zhang W, Lu X. Shifts in bacterial diversity, interactions and microbial elemental cycling genes under cadmium contamination in paddy soil: Implications for altered ecological function. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132544. [PMID: 37738847 DOI: 10.1016/j.jhazmat.2023.132544] [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: 06/24/2023] [Revised: 09/06/2023] [Accepted: 09/11/2023] [Indexed: 09/24/2023]
Abstract
Cadmium (Cd) contamination has become an emergent environmental issue in agroecosystems worldwide. The impacts of Cd on microbial community and their ecological functional remain unrevealed. This study investigated the response of bacterial community and microbial ecological functions to Cd contamination in paddy soil of East China. Bacterial diversity and community structure significantly changed under Cd contamination. Proteobacteria and Acidobacteria were identified as biomarkers to indicate Cd contamination. The overall elemental cycling genes abundance was negatively correlated to soil Cd content. Acetyl-CoA synthesis, organic N mineralization, N fixation and nitrous reduction genes were especially sensitive to elevated Cd stress, resulting in loss of microbial derived soil C and N pool and increase in N2O emission potential. Bacteria interactions were sparser yet more competitive under Cd contamination. Cd resistant genera Massilia, Burkholderia, Streptomyces and Methylobacterium were essential to bacterial interactions via building connections with non-resistant species. Microbial Cd immobilization potential by urea hydrolysis was enhanced under Cd contamination, with Massilia being the keystone functional taxa involved in this process. Our study elucidated the ecological risks of altered microbial functions under Cd contamination in paddy soil, as well as the significance of Cd resistant bacteria to microbial community and ecological functionality.
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Affiliation(s)
- Yuntao Li
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Key Laboratory of Agro-Environment in downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs of China, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Yan Gao
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Key Laboratory of Agro-Environment in downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs of China, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - Wei Chen
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Key Laboratory of Agro-Environment in downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs of China, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Weiguo Zhang
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Key Laboratory of Agro-Environment in downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs of China, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xin Lu
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Key Laboratory of Agro-Environment in downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs of China, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
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2
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Jayachandran D, Banerjee S, Chundawat SPS. Plant cellulose synthase membrane protein isolation directly from Pichia pastoris protoplasts, liposome reconstitution, and its enzymatic characterization. Protein Expr Purif 2023:106309. [PMID: 37211149 DOI: 10.1016/j.pep.2023.106309] [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: 04/26/2023] [Revised: 05/17/2023] [Accepted: 05/18/2023] [Indexed: 05/23/2023]
Abstract
Cellulose is synthesized by a plant cell membrane-integrated processive glycosyltransferase (GT) called cellulose synthase (CesA). Since only a few of these plant CesAs have been purified and characterized to date, there are huge gaps in our mechanistic understanding of these enzymes. The biochemistry and structural biology studies of CesAs are currently hampered by challenges associated with their expression and extraction at high yields. To aid in understanding CesA reaction mechanisms and to provide a more efficient CesA extraction method, two putative plant CesAs - PpCesA5 from Physcomitrella patens and PttCesA8 from Populus tremula x tremuloides that are involved in primary and secondary cell wall formation in plants were expressed using Pichia pastoris as an expression host. We developed a protoplast-based membrane protein extraction approach to directly isolate these membrane-bound enzymes, as confirmed by immunoblotting and mass spectrometry-based analyses. Our method gives 3-4-fold higher purified protein yield than the standard cell homogenization protocol. Our method resulted in liposome reconstituted CesA5 and CesA8 enzymes with similar Michaelis-Menten kinetic constants, Km = 167 μM, 108 μM and Vmax = 7.88 × 10-5 μmol/min, 4.31 × 10-5 μmol/min, respectively, in concurrence with the previous studies for enzymes isolated using the standard protocol. Taken together, these results suggest that CesAs involved in primary and secondary cell wall formation can be expressed and purified using a simple and more efficient extraction method. This protocol could help isolate enzymes that unravel the mechanism of native and engineered cellulose synthase complexes involved in plant cell wall biosynthesis.
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Affiliation(s)
- Dharanidaran Jayachandran
- Department of Chemical and Biochemical Engineering, Rutgers-The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Shoili Banerjee
- Department of Chemical and Biochemical Engineering, Rutgers-The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Shishir P S Chundawat
- Department of Chemical and Biochemical Engineering, Rutgers-The State University of New Jersey, Piscataway, NJ, 08854, USA.
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3
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Martirani-VonAbercron SM, Pacheco-Sánchez D. Bacterial cellulose: A highly versatile nanomaterial. Microb Biotechnol 2023; 16:1174-1178. [PMID: 36892420 DOI: 10.1111/1751-7915.14243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 03/10/2023] Open
Affiliation(s)
- Sophie-Marie Martirani-VonAbercron
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Daniel Pacheco-Sánchez
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
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4
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The Roles of the Various Cellulose Biosynthesis Operons in Komagataeibacter hansenii ATCC 23769. Appl Environ Microbiol 2022; 88:e0246021. [PMID: 35319232 DOI: 10.1128/aem.02460-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellulose is the most abundant biopolymer on earth and offers versatile applicability in biotechnology. Bacterial cellulose, especially, is an attractive material because it represents pure microcrystalline cellulose. The cellulose synthase complex of acetic acid bacteria serves as a model for general studies on (bacterial) cellulose synthesis. The genome of Komagataeibacter hansenii ATCC 23769 encodes three cellulose synthase (CS) operons of different sizes and gene compositions. This implies the question of which role each of the three CS-encoding operons, bcsAB1, bcsAB2, and bcsAB3, plays in overall cellulose synthesis. Therefore, we constructed markerless deletions in K. hansenii ATCC 23769, yielding mutant strains that expressed only one of the three CSs. Apparently, BcsAB1 is the only CS that produces fibers of crystalline cellulose. The markerless deletion of bcsAB1 resulted in a nonfiber phenotype in scanning electron microscopy analysis. Expression of the other CSs resulted in a different, nonfibrous extracellular polymeric substance (nfEPS) structure wrapping the cells, which is proposed to contain acetylated cellulose. Transcription analysis revealed that all CSs were expressed continuously and that bcsAB2 showed a higher transcription level than bcsAB1. Moreover, we were able to link the expression of diguanylate cyclase B (dgcB) to cellulose production. IMPORTANCE Acetic acid bacteria form a massive biofilm called "mother of vinegar," which is built of cellulose fibers. Bacterial cellulose is an appealing biomaterial with manifold applications in biomedicine and biotechnology. Because most cellulose-producing acetic acid bacteria express several cellulose synthase operons, a deeper understanding of their contribution to the synthesis of modified forms of cellulose fibers within a natural biofilm is of special interest. For the first time, we were able to identify the contribution of each of the three cellulose synthases to cellulose formation in Komagataeibacter hansenii ATCC 23769 after a chromosomal clean deletion. Moreover, we were able to depict their roles in spatial composition of the biofilm. These findings might be applicable in the future for naturally modified biomaterials with novel properties.
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Li G, Wang L, Deng Y, Wei Q. Research progress of the biosynthetic strains and pathways of bacterial cellulose. J Ind Microbiol Biotechnol 2022; 49:kuab071. [PMID: 34549273 PMCID: PMC9113090 DOI: 10.1093/jimb/kuab071] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 09/17/2021] [Indexed: 11/14/2022]
Abstract
Bacterial cellulose is a glucose biopolymer produced by microorganisms and widely used as a natural renewable and sustainable resource in the world. However, few bacterial cellulose-producing strains and low yield of cellulose greatly limited the development of bacterial cellulose. In this review, we summarized the 30 cellulose-producing bacteria reported so far, including the physiological functions and the metabolic synthesis mechanism of bacterial cellulose, and the involved three kinds of cellulose synthases (type I, type II, and type III), which are expected to provide a reference for the exploration of new cellulose-producing microbes.
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Affiliation(s)
- Guohui Li
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China
| | - Li Wang
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China
| | - Yu Deng
- National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China
| | - Qufu Wei
- Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China
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Buldum G, Mantalaris A. Systematic Understanding of Recent Developments in Bacterial Cellulose Biosynthesis at Genetic, Bioprocess and Product Levels. Int J Mol Sci 2021; 22:ijms22137192. [PMID: 34281246 PMCID: PMC8268586 DOI: 10.3390/ijms22137192] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 02/06/2023] Open
Abstract
Engineering biological processes has become a standard approach to produce various commercially valuable chemicals, therapeutics, and biomaterials. Among these products, bacterial cellulose represents major advances to biomedical and healthcare applications. In comparison to properties of plant cellulose, bacterial cellulose (BC) shows distinctive characteristics such as a high purity, high water retention, and biocompatibility. However, low product yield and extensive cultivation times have been the main challenges in the large-scale production of BC. For decades, studies focused on optimization of cellulose production through modification of culturing strategies and conditions. With an increasing demand for BC, researchers are now exploring to improve BC production and functionality at different categories: genetic, bioprocess, and product levels as well as model driven approaches targeting each of these categories. This comprehensive review discusses the progress in BC platforms categorizing the most recent advancements under different research focuses and provides systematic understanding of the progress in BC biosynthesis. The aim of this review is to present the potential of ‘modern genetic engineering tools’ and ‘model-driven approaches’ on improving the yield of BC, altering the properties, and adding new functionality. We also provide insights for the future perspectives and potential approaches to promote BC use in biomedical applications.
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Affiliation(s)
- Gizem Buldum
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK;
| | - Athanasios Mantalaris
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Correspondence:
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7
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Jacek P, Dourado F, Gama M, Bielecki S. Molecular aspects of bacterial nanocellulose biosynthesis. Microb Biotechnol 2019; 12:633-649. [PMID: 30883026 PMCID: PMC6559022 DOI: 10.1111/1751-7915.13386] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/03/2019] [Accepted: 02/08/2019] [Indexed: 11/27/2022] Open
Abstract
Bacterial nanocellulose (BNC) produced by aerobic bacteria is a biopolymer with sophisticated technical properties. Although the potential for economically relevant applications is huge, the cost of BNC still limits its application to a few biomedical devices and the edible product Nata de Coco, made available by traditional fermentation methods in Asian countries. Thus, a wider economic relevance of BNC is still dependent on breakthrough developments on the production technology. On the other hand, the development of modified strains able to overproduce BNC with new properties - e.g. porosity, density of fibres crosslinking, mechanical properties, etc. - will certainly allow to overcome investment and cost production issues and enlarge the scope of BNC applications. This review discusses current knowledge about the molecular basis of BNC biosynthesis, its regulations and, finally, presents a perspective on the genetic modification of BNC producers made possible by the new tools available for genetic engineering.
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Affiliation(s)
- Paulina Jacek
- Institute of Technical BiochemistryLodz University of Technology4/10 Stefanowskiego Str90‐924LodzPoland
| | - Fernando Dourado
- Centre of Biological EngineeringUniversity of MinhoCampus de Gualtar4710‐057BragaPortugal
| | - Miguel Gama
- Centre of Biological EngineeringUniversity of MinhoCampus de Gualtar4710‐057BragaPortugal
| | - Stanisław Bielecki
- Institute of Technical BiochemistryLodz University of Technology4/10 Stefanowskiego Str90‐924LodzPoland
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8
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Structural and rheological characterization of bacterial cellulose gels obtained from Gluconacetobacter genus. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.01.060] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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van Zyl EM, Coburn JM. Hierarchical structure of bacterial-derived cellulose and its impact on biomedical applications. Curr Opin Chem Eng 2019. [DOI: 10.1016/j.coche.2019.04.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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McManus JB, Wilson L, Yang H, Kubicki JD, Tien M. Kinetic analysis of cellulose synthase of Gluconacetobacter hansenii in whole cells and in purified form. Enzyme Microb Technol 2018; 119:24-29. [PMID: 30243383 DOI: 10.1016/j.enzmictec.2018.08.005] [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: 07/13/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022]
Abstract
The Gram-negative bacterium, Gluconacetobacter hansenii, has been long studied and is a model for cellulose synthesis. It produces cellulose, using the enzyme AcsA-AcsB, of exceptionally high crystallinity in comparison to the cellulose of higher plants. We determined the rate of cellulose synthesis in whole cells measured as moles of glucose incorporated into cellulose per second per mole of enzyme. This was determined by quantifying the rate of cellulose synthesis (over a short time span, such that the enzyme concentration is not changing due to cell growth) and the amount of enzyme in the whole cell by quantitative western blotting. We found that the whole cell rate of 24 s-1 is much faster than the kcat, measured from steady-state kinetic analysis, of 1.7 s-1. Our whole cell rates are consistent with previous studies using microscopy. We postulate that the rationale for this difference is the presence of an alternative in vivo priming mechanism. This in turn can increase the rate of initiation, which we previously postulated to be the rate-limiting step in catalysis.
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Affiliation(s)
- John B McManus
- Department of Biochemistry and Molecular Biology, 305 South Frear, University Park, The Pennsylvania State University, PA, 16802, USA
| | - Liza Wilson
- Department of Biology, University Park, The Pennsylvania State University, PA, 16802, USA
| | - Hui Yang
- Department of Biology, University Park, The Pennsylvania State University, PA, 16802, USA
| | - James D Kubicki
- Department of Geological Sciences, University of Texas at El Paso, El Paso, TX, 79968, USA
| | - Ming Tien
- Department of Biochemistry and Molecular Biology, 305 South Frear, University Park, The Pennsylvania State University, PA, 16802, USA.
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McManus JB, Yang H, Wilson L, Kubicki JD, Tien M. Initiation, Elongation, and Termination of Bacterial Cellulose Synthesis. ACS OMEGA 2018; 3:2690-2698. [PMID: 30023847 PMCID: PMC6044951 DOI: 10.1021/acsomega.7b01808] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/19/2018] [Indexed: 05/30/2023]
Abstract
Cellulose is the major component of the plant cell wall and composed of β-linked glucose units. Use of cellulose is greatly impacted by its physical properties, which are dominated by the number of individual cellulose strand within each fiber and the average length of each strand. Our work described herein provides a complete mechanism for cellulose synthase accounting for its processivity and mechanism of initiation. Using ionic liquids and gel permeation chromatography, we obtain kinetic constants for initiation, elongation, and termination (release of the cellulose strand from the enzyme) for two bacterial cellulose synthases (Gluconacetobacter hansenii and Rhodobacter sphaeroides). Our results show that initiation of synthesis is primer-independent. After initiation, the enzyme undergoes multiple cycles of elongation until the strand is released. The rate of elongation is much faster than that of steady-state turnover. Elongation requires cyclic addition of glucose (from uridine diphosphate-glucose) and then strand translocation by one glucose unit. Translocations greater than one glucose unit result in termination requiring reinitiation. The rate of the strand release, relative to the rate of elongation, determines the processivity of the enzyme. This mechanism and the measured rate constants were supported by kinetic simulation. With the experimentally determined rate constants, we are able to simulate steady-state kinetics and mimic the size distribution of the product. Thus, our results provide for the first time a mechanism for cellulose synthase that accounts for initiation, elongation, and termination.
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Affiliation(s)
- John B. McManus
- Department
of Biochemistry and Molecular Biology and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Hui Yang
- Department
of Biochemistry and Molecular Biology and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Liza Wilson
- Department
of Biochemistry and Molecular Biology and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - James D. Kubicki
- Department
of Geological Sciences, University of Texas
at El Paso, El Paso, Texas 79968, United
States
| | - Ming Tien
- Department
of Biochemistry and Molecular Biology and Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Wang SS, Han YH, Ye YX, Shi XX, Xiang P, Chen DL, Li M. Physicochemical characterization of high-quality bacterial cellulose produced by Komagataeibacter sp. strain W1 and identification of the associated genes in bacterial cellulose production. RSC Adv 2017. [DOI: 10.1039/c7ra08391b] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Komagataeibacter sp. W1 produced high-quality BC, the properties and synthesis mechanisms of which were analyzed by SEM, XRD and FTIR, and genome sequencing, respectively.
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Affiliation(s)
- Shan-Shan Wang
- College of Life Science
- Fujian Normal University
- Fuzhou
- China
- Quangang Petrochemical Research Institute
| | - Yong-He Han
- Quangang Petrochemical Research Institute
- Fujian Normal University
- Quanzhou
- China
| | - Yu-Xuan Ye
- State Key Laboratory of Pollution Control and Resource Reuse
- School of the Environment
- Nanjing University
- China
| | - Xiao-Xia Shi
- State Key Laboratory of Pollution Control and Resource Reuse
- School of the Environment
- Nanjing University
- China
| | - Ping Xiang
- State Key Laboratory of Pollution Control and Resource Reuse
- School of the Environment
- Nanjing University
- China
| | - Deng-Long Chen
- Quangang Petrochemical Research Institute
- Fujian Normal University
- Quanzhou
- China
- College of Environmental Science and Engineering
| | - Min Li
- College of Life Science
- Fujian Normal University
- Fuzhou
- China
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Structure of the Cellulose Synthase Complex of Gluconacetobacter hansenii at 23.4 Å Resolution. PLoS One 2016; 11:e0155886. [PMID: 27214134 PMCID: PMC4877109 DOI: 10.1371/journal.pone.0155886] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 05/05/2016] [Indexed: 01/08/2023] Open
Abstract
Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA) exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC) that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsD in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 Å for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. The results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation components, and support the hypothesis that it is the extrusion mechanism and order in linearly arrayed TCs that enables production of crystalline cellulose.
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