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Insights to the Structural Basis for the Stereospecificity of the Escherichia coli Phytase, AppA. Int J Mol Sci 2022; 23:ijms23116346. [PMID: 35683026 PMCID: PMC9181005 DOI: 10.3390/ijms23116346] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 05/30/2022] [Accepted: 06/02/2022] [Indexed: 02/01/2023] Open
Abstract
AppA, the Escherichia coli periplasmic phytase of clade 2 of the histidine phosphatase (HP2) family, has been well-characterized and successfully engineered for use as an animal feed supplement. AppA is a 1D-6-phytase and highly stereospecific but transiently accumulates 1D-myo-Ins(2,3,4,5)P4 and other lower phosphorylated intermediates. If this bottleneck in liberation of orthophosphate is to be obviated through protein engineering, an explanation of its rather rigid preference for the initial site and subsequent cleavage of phytic acid is required. To help explain this behaviour, the role of the catalytic proton donor residue in determining AppA stereospecificity was investigated. Four variants were generated by site-directed mutagenesis of the active site HDT amino acid sequence motif containing the catalytic proton donor, D304. The identity and position of the prospective proton donor residue was found to strongly influence stereospecificity. While the wild-type enzyme has a strong preference for 1D-6-phytase activity, a marked reduction in stereospecificity was observed for a D304E variant, while a proton donor-less mutant (D304A) displayed exclusive 1D-1/3-phytase activity. High-resolution X-ray crystal structures of complexes of the mutants with a non-hydrolysable substrate analogue inhibitor point to a crucial role played by D304 in stereospecificity by influencing the size and polarity of specificity pockets A and B. Taken together, these results provide the first evidence for the involvement of the proton donor residue in determining the stereospecificity of HP2 phytases and prepares the ground for structure-informed engineering studies targeting the production of animal feed enzymes capable of the efficient and complete dephosphorylation of dietary phytic acid.
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Terán-Ramírez C, Mares-Alejandre RE, Estrada-González AL, Muñoz-Muñoz PLA, Ramos-Ibarra MA. Structure-Function Relationship Study of a Secretory Amoebic Phosphatase: A Computational-Experimental Approach. Int J Mol Sci 2021; 22:ijms22042164. [PMID: 33671604 PMCID: PMC7926622 DOI: 10.3390/ijms22042164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 11/16/2022] Open
Abstract
Phosphatases are hydrolytic enzymes that cleave the phosphoester bond of numerous substrates containing phosphorylated residues. The typical classification divides them into acid or alkaline depending on the pH at which they have optimal activity. The histidine phosphatase (HP) superfamily is a large group of functionally diverse enzymes characterized by having an active-site His residue that becomes phosphorylated during catalysis. HP enzymes are relevant biomolecules due to their current and potential application in medicine and biotechnology. Entamoeba histolytica, the causative agent of human amoebiasis, contains a gene (EHI_146950) that encodes a putative secretory acid phosphatase (EhHAPp49), exhibiting sequence similarity to histidine acid phosphatase (HAP)/phytase enzymes, i.e., branch-2 of HP superfamily. To assess whether it has the potential as a biocatalyst in removing phosphate groups from natural substrates, we studied the EhHAPp49 structural and functional features using a computational-experimental approach. Although the combined outcome of computational analyses confirmed its structural similarity with HP branch-2 proteins, the experimental results showed that the recombinant enzyme (rEhHAPp49) has negligible HAP/phytase activity. Nonetheless, results from supplementary activity evaluations revealed that rEhHAPp49 exhibits Mg2+-dependent alkaline pyrophosphatase activity. To our knowledge, this study represents the first computational-experimental characterization of EhHAPp49, which offers further insights into the structure-function relationship and the basis for future research.
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Guo Y, Zhou D, Zhang H, Zhang NN, Qi X, Chen X, Chen Q, Li J, Ge H, Teng YB. Structural insights into a new substrate binding mode of a histidine acid phosphatase from Legionella pneumophila. Biochem Biophys Res Commun 2021; 540:90-94. [PMID: 33450485 DOI: 10.1016/j.bbrc.2020.12.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 10/22/2022]
Abstract
MapA is a histidine acid phosphatase (HAP) from Legionella pneumophila that catalyzes the hydroxylation of a phosphoryl group from phosphomonoesters by an active-site histidine. Several structures of HAPs, including MapA, in complex with the inhibitor tartrate have been solved and the substrate binding tunnel identified; however, the substrate recognition mechanism remains unknown. To gain insight into the mechanism of substrate recognition, the crystal structures of apo-MapA and the MapAD281A mutant in complex with 5'-AMP were solved at 2.2 and 2.6 Å resolution, respectively. The structure of the MapAD281A/5'-AMP complex reveals that the 5'-AMP fits fully into the substrate binding tunnel, with the 2'-hydroxyl group of the ribose moiety stabilized by Glu201 and the adenine moiety sandwiched between His205 and Phe237. This is the second structure of a HAP/AMP complex solved with 5'-AMP binding in a unique manner in the active site. The structure presents a new substrate recognition mechanism of HAPs.
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Affiliation(s)
- Yu Guo
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, 230032, People's Republic of China.
| | - Dan Zhou
- Institute of Health Sciences and School of Life Science, Anhui University, Hefei, Anhui, 230601, People's Republic of China.
| | - Hui Zhang
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, 230032, People's Republic of China.
| | - Nan-Nan Zhang
- Institute of Health Sciences and School of Life Science, Anhui University, Hefei, Anhui, 230601, People's Republic of China.
| | - Xiaoyu Qi
- Department of Otorhinolaryngology-Head and Neck Surgery, The First Affiliated Hospital of University of Science and Technology of China, Hefei, 230001, People's Republic of China.
| | - Xiaofang Chen
- Institute of Health Sciences and School of Life Science, Anhui University, Hefei, Anhui, 230601, People's Republic of China.
| | - Qi Chen
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, 230032, People's Republic of China.
| | - Jing Li
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, 230032, People's Republic of China.
| | - Honghua Ge
- Institute of Health Sciences and School of Life Science, Anhui University, Hefei, Anhui, 230601, People's Republic of China.
| | - Yan-Bin Teng
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, 230032, People's Republic of China.
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Acquistapace IM, Zi Etek MA, Li AWH, Salmon M, Kühn I, Bedford MR, Brearley CA, Hemmings AM. Snapshots during the catalytic cycle of a histidine acid phytase reveal an induced-fit structural mechanism. J Biol Chem 2020; 295:17724-17737. [PMID: 33454010 PMCID: PMC7762957 DOI: 10.1074/jbc.ra120.015925] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/10/2020] [Indexed: 11/16/2022] Open
Abstract
Highly engineered phytases, which sequentially hydrolyze the hexakisphosphate ester of inositol known as phytic acid, are routinely added to the feeds of monogastric animals to improve phosphate bioavailability. New phytases are sought as starting points to further optimize the rate and extent of dephosphorylation of phytate in the animal digestive tract. Multiple inositol polyphosphate phosphatases (MINPPs) are clade 2 histidine phosphatases (HP2P) able to carry out the stepwise hydrolysis of phytate. MINPPs are not restricted by a strong positional specificity making them attractive targets for development as feed enzymes. Here, we describe the characterization of a MINPP from the Gram-positive bacterium Bifidobacterium longum (BlMINPP). BlMINPP has a typical HP2P-fold but, unusually, possesses a large α-domain polypeptide insertion relative to other MINPPs. This insertion, termed the U-loop, spans the active site and contributes to substrate specificity pockets underpopulated in other HP2Ps. Mutagenesis of U-loop residues reveals its contribution to enzyme kinetics and thermostability. Moreover, four crystal structures of the protein along the catalytic cycle capture, for the first time in an HP2P, a large ligand-driven α-domain motion essential to allow substrate access to the active site. This motion recruits residues both downstream of a molecular hinge and on the U-loop to participate in specificity subsites, and mutagenesis identified a mobile lysine residue as a key determinant of positional specificity of the enzyme. Taken together, these data provide important new insights to the factors determining stability, substrate recognition, and the structural mechanism of hydrolysis in this industrially important group of enzymes.
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Affiliation(s)
| | - Monika A Zi Etek
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Arthur W H Li
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Melissa Salmon
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | | | | | - Charles A Brearley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Andrew M Hemmings
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom; School of Chemistry, University of East Anglia, Norwich, United Kingdom.
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Portlock TJ, Tyson JY, Dantu SC, Rehman S, White RC, McIntire IE, Sewell L, Richardson K, Shaw R, Pandini A, Cianciotto NP, Garnett JA. Structure, Dynamics and Cellular Insight Into Novel Substrates of the Legionella pneumophila Type II Secretion System. Front Mol Biosci 2020; 7:112. [PMID: 32656228 PMCID: PMC7325957 DOI: 10.3389/fmolb.2020.00112] [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: 03/04/2020] [Accepted: 05/12/2020] [Indexed: 12/13/2022] Open
Abstract
Legionella pneumophila is a Gram-negative bacterium that is able to replicate within a broad range of aquatic protozoan hosts. L. pneumophila is also an opportunistic human pathogen that can infect macrophages and epithelia in the lung and lead to Legionnaires’ disease. The type II secretion system is a key virulence factor of L. pneumophila and is used to promote bacterial growth at low temperatures, regulate biofilm formation, modulate host responses to infection, facilitate bacterial penetration of mucin gels and is necessary for intracellular growth during the initial stages of infection. The L. pneumophila type II secretion system exports at least 25 substrates out of the bacterium and several of these, including NttA to NttG, contain unique amino acid sequences that are generally not observed outside of the Legionella genus. NttA, NttC, and NttD are required for infection of several amoebal species but it is unclear what influence other novel substrates have within their host. In this study, we show that NttE is required for optimal infection of Acanthamoeba castellanii and Vermamoeba vermiformis amoeba and is essential for the typical colony morphology of L. pneumophila. In addition, we report the atomic structures of NttA, NttC, and NttE and through a combined biophysical and biochemical hypothesis driven approach we propose novel functions for these substrates during infection. This work lays the foundation for future studies into the mechanistic understanding of novel type II substrate functions and how these relate to L. pneumophila ecology and disease.
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Affiliation(s)
- Theo J Portlock
- Centre for Host-Microbiome Interactions, Dental Institute, King's College London, London, United Kingdom.,Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Jessica Y Tyson
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Sarath C Dantu
- Department of Computer Science, Brunel University London, Uxbridge, United Kingdom
| | - Saima Rehman
- Centre for Host-Microbiome Interactions, Dental Institute, King's College London, London, United Kingdom
| | - Richard C White
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Ian E McIntire
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Lee Sewell
- Centre for Host-Microbiome Interactions, Dental Institute, King's College London, London, United Kingdom
| | - Katherine Richardson
- Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Rosie Shaw
- Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Alessandro Pandini
- Department of Computer Science, Brunel University London, Uxbridge, United Kingdom
| | - Nicholas P Cianciotto
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - James A Garnett
- Centre for Host-Microbiome Interactions, Dental Institute, King's College London, London, United Kingdom.,Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
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White RC, Cianciotto NP. Assessing the impact, genomics and evolution of type II secretion across a large, medically important genus: the Legionella type II secretion paradigm. Microb Genom 2019; 5. [PMID: 31166887 PMCID: PMC6617341 DOI: 10.1099/mgen.0.000273] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The type II secretion system (T2SS) plays a major role in promoting bacterial survival in the environment and in human hosts. One of the best characterized T2SS is that of Legionella pneumophila, the agent of Legionnaires’ disease. Secreting at least 25 proteins, including degradative enzymes, eukaryotic-like proteins and novel effectors, this T2SS contributes to the ability of L. pneumophila to grow at low temperatures, infect amoebal and macrophage hosts, damage lung tissue, evade the immune system, and undergo sliding motility. The genes encoding the T2SS are conserved across the genus Legionella, which includes 62 species and >30 pathogens in addition to L. pneumophila. The vast majority of effectors associated with L. pneumophila are shared by a large number of Legionella species, hinting at a critical role for them in the ecology of Legionella as a whole. However, no other species has the same repertoire as L. pneumophila, with, as a general rule, phylogenetically more closely related species sharing similar sets of effectors. T2SS effectors that are involved in infection of a eukaryotic host(s) are more prevalent throughout Legionella, indicating that they are under stronger selective pressure. The Legionella T2SS apparatus is closest to that of Aquicella (another parasite of amoebae), and a significant number of L. pneumophila effectors have their closest homologues in Aquicella. Thus, the T2SS of L. pneumophila probably originated within the order Legionellales, with some of its effectors having arisen within that Aquicella-like progenitor, while other effectors derived from the amoebal host, mimiviruses, fungi and less closely related bacteria.
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Affiliation(s)
- Richard C White
- 1 Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, IL 60611, USA
| | - Nicholas P Cianciotto
- 1 Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, IL 60611, USA
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Zhang H, Yang L, Ding W, Ma Y. Theoretical Studies on the Catalytic Cycle of Histidine Acid Phosphatases Revealing an Acid Proof Mechanism. J Phys Chem B 2018; 122:7530-7538. [DOI: 10.1021/acs.jpcb.8b04808] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hao Zhang
- College of Life Science and Engineering, Northwest Minzu University, Lanzhou 730030, P. R. China
| | - Ling Yang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Wanjian Ding
- College of Chemistry, Beijing Normal University, Beijing 100086, P. R. China
| | - Yingying Ma
- Institute of Mining Technology, Inner Mongolia University of Technology. Hohhot 010051, P. R. China
- Inner Mongolia Key Laboratory of Theoretical and Computational Chemistry Simulation. Hohhot 010051, P. R. China
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Type II Secretion-Dependent Aminopeptidase LapA and Acyltransferase PlaC Are Redundant for Nutrient Acquisition during Legionella pneumophila Intracellular Infection of Amoebas. mBio 2018; 9:mBio.00528-18. [PMID: 29666285 PMCID: PMC5904407 DOI: 10.1128/mbio.00528-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Legionella pneumophila genes encoding LapA, LapB, and PlaC were identified as the most highly upregulated type II secretion (T2S) genes during infection of Acanthamoeba castellanii, although these genes had been considered dispensable on the basis of the behavior of mutants lacking either lapA and lapB or plaC A plaC mutant showed even higher levels of lapA and lapB transcripts, and a lapA lapB mutant showed heightening of plaC mRNA levels, suggesting that the role of the LapA/B aminopeptidase is compensatory with respect to that of the PlaC acyltransferase. Hence, we made double mutants and found that lapA plaC mutants have an ~50-fold defect during infection of A. castellanii These data revealed, for the first time, the importance of LapA in any sort of infection; thus, we purified LapA and defined its crystal structure, activation by another T2S-dependent protease (ProA), and broad substrate specificity. When the amoebal infection medium was supplemented with amino acids, the defect of the lapA plaC mutant was reversed, implying that LapA generates amino acids for nutrition. Since the LapA and PlaC data did not fully explain the role of T2S in infection, we identified, via proteomic analysis, a novel secreted protein (NttD) that promotes infection of A. castellanii A lapA plaC nttD mutant displayed an even greater (100-fold) defect, demonstrating that the LapA, PlaC, and NttD data explain, to a significant degree, the importance of T2S. LapA-, PlaC-, and NttD-like proteins had distinct distribution patterns within and outside the Legionella genus. LapA was notable for having as its closest homologue an A. castellanii protein.IMPORTANCE Transmission of L. pneumophila to humans is facilitated by its ability to grow in Acanthamoeba species. We previously documented that type II secretion (T2S) promotes L. pneumophila infection of A. castellanii Utilizing transcriptional analysis and proteomics, double and triple mutants, and crystal structures, we defined three secreted substrates/effectors that largely clarify the role of T2S during infection of A. castellanii Particularly interesting are the unique functional overlap between an acyltransferase (PlaC) and aminopeptidase (LapA), the broad substrate specificity and eukaryotic-protein-like character of LapA, and the novelty of NttD. Linking LapA to amino acid acquisition, we defined, for the first time, the importance of secreted aminopeptidases in intracellular infection. Bioinformatic investigation, not previously applied to T2S, revealed that effectors originate from diverse sources and distribute within the Legionella genus in unique ways. The results of this study represent a major advance in understanding Legionella ecology and pathogenesis, bacterial secretion, and the evolution of intracellular parasitism.
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