1
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Diep P, Stogios PJ, Evdokimova E, Savchenko A, Mahadevan R, Yakunin AF. Ni(II)-binding affinity of CcNikZ-II and its homologs: the role of the HH-prong and variable loop revealed by structural and mutational studies. FEBS J 2024; 291:2980-2993. [PMID: 38555564 DOI: 10.1111/febs.17125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/30/2024] [Accepted: 03/13/2024] [Indexed: 04/02/2024]
Abstract
Extracytoplasmic Ni(II)-binding proteins (NiBPs) are molecular shuttles involved in cellular nickel uptake. Here, we determined the crystal structure of apo CcNikZ-II at 2.38 Å, which revealed a Ni(II)-binding site comprised of the double His (HH-)prong (His511, His512) and a short variable (v-)loop nearby (Thr59-Thr64, TEDKYT). Mutagenesis of the site identified Glu60 and His511 as critical for high affinity Ni(II)-binding. Phylogenetic analysis showed 15 protein clusters with two groups containing the HH-prong. Metal-binding assays with 11 purified NiBPs containing this feature yielded higher Ni(II)-binding affinities. Replacement of the wild type v-loop with those from other NiBPs improved the affinity by up to an order of magnitude. This work provides molecular insights into the determinants for Ni(II) affinity and paves way for NiBP engineering.
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Affiliation(s)
- Patrick Diep
- Department of Chemical Engineering and Applied Chemistry, BioZone - Centre for Applied Bioscience and Bioengineering, University of Toronto, Toronto, Ontario, Canada
- Systems & Synthetic Biology Group, Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, BioZone - Centre for Applied Bioscience and Bioengineering, University of Toronto, Toronto, Ontario, Canada
| | - Elena Evdokimova
- Department of Chemical Engineering and Applied Chemistry, BioZone - Centre for Applied Bioscience and Bioengineering, University of Toronto, Toronto, Ontario, Canada
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, BioZone - Centre for Applied Bioscience and Bioengineering, University of Toronto, Toronto, Ontario, Canada
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, BioZone - Centre for Applied Bioscience and Bioengineering, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Yakunin
- Department of Chemical Engineering and Applied Chemistry, BioZone - Centre for Applied Bioscience and Bioengineering, University of Toronto, Toronto, Ontario, Canada
- Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, Wales, UK
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2
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Kienlein M, Zacharias M. How arginine inhibits substrate-binding domain 2 elucidated using molecular dynamics simulations. Protein Sci 2024; 33:e5077. [PMID: 38888275 PMCID: PMC11184577 DOI: 10.1002/pro.5077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/19/2024] [Accepted: 05/28/2024] [Indexed: 06/20/2024]
Abstract
The substrate-binding domain 2 (SBD2) is an important part of the bacterial glutamine (GLN) transporter and mediates binding and delivery of GLN to the transporter translocation subunit. The SBD2 consists of two domains, D1 and D2, that bind GLN in the space between domains in a closed structure. In the absence of ligand, the SBD2 adopts an open conformation with larger space between domains. The GLN binding and closing are essential for the subsequent transport into the cell. Arginine (ARG) can also bind to SBD2 but does not induce closing and inhibits GLN transport. We use atomistic molecular dynamics (MD) simulations in explicit solvent to study ARG binding in the presence of the open SBD2 structure and observed reversible binding to the native GLN binding site with similar contacts but no transition to a closed SBD2 state. Absolute binding free energy simulations predict a considerable binding affinity of ARG and GLN to the binding site on the D1 domain. Free energy simulations to induce subsequent closing revealed a strong free energy penalty in case of ARG binding in contrast to GLN binding that favors the closed SBD2 state but still retains a free energy barrier for closing. The simulations allowed the identification of the molecular origin of the closing penalty in case of bound ARG and suggested a mutation of lysine at position 373 to alanine that strongly reduced the penalty and allowed closing even in the presence of bound ARG. The study offers an explanation of the molecular mechanism of how ARG competitively inhibits GLN from binding to SBD2 and from triggering the transition to a closed conformation. The proposed Lys373Ala mutation shows promise as a potential tool to validate whether a conformational mismatch between open SBD2 and the translocator is responsible for preventing ARG uptake to the cell.
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Affiliation(s)
- Maximilian Kienlein
- Center for Functional Protein Assemblies (CPA)Technical University of MunichGarchingGermany
| | - Martin Zacharias
- Center for Functional Protein Assemblies (CPA)Technical University of MunichGarchingGermany
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3
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Dutta A, Kanaujia SP. The Structural Features of MlaD Illuminate its Unique Ligand-Transporting Mechanism and Ancestry. Protein J 2024; 43:298-315. [PMID: 38347327 DOI: 10.1007/s10930-023-10179-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2023] [Indexed: 05/01/2024]
Abstract
The membrane-associated solute-binding protein (SBP) MlaD of the maintenance of lipid asymmetry (Mla) system has been reported to help the transport of phospholipids (PLs) between the outer and inner membranes of Gram-negative bacteria. Despite the availability of structural information, the molecular mechanism underlying the transport of PLs and the ancestry of the protein MlaD remain unclear. In this study, we report the crystal structures of the periplasmic region of MlaD from Escherichia coli (EcMlaD) at a resolution range of 2.3-3.2 Å. The EcMlaD protomer consists of two distinct regions, viz. N-terminal β-barrel fold consisting of seven strands (referred to as MlaD domain) and C-terminal α-helical domain (HD). The protein EcMlaD oligomerizes to give rise to a homo-hexameric ring with a central channel that is hydrophobic and continuous with a variable diameter. Interestingly, the structural analysis revealed that the HD, instead of the MlaD domain, plays a critical role in determining the oligomeric state of the protein. Based on the analysis of available structural information, we propose a working mechanism of PL transport, viz. "asymmetric protomer movement (APM)". Wherein half of the EcMlaD hexamer would rise in the periplasmic side along with an outward movement of pore loops, resulting in the change of the central channel geometry. Furthermore, this study highlights that, unlike typical SBPs, EcMlaD possesses a fold similar to EF/AMT-type beta(6)-barrel and a unique ancestry. Altogether, the findings firmly establish EcMlaD to be a non-canonical SBP with a unique ligand-transport mechanism.
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Affiliation(s)
- Angshu Dutta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India
| | - Shankar Prasad Kanaujia
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India.
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4
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Hu T, Yang X, Zhu Y, Liu F, Yang X, Xiong Z, Liang J, Lin Z, Ran Y, Guddat LW, Rao Z, Zhang B. Molecular basis for substrate transport of Mycobacterium tuberculosis ABC importer DppABCD. SCIENCE ADVANCES 2024; 10:eadk8521. [PMID: 38507491 PMCID: PMC10954201 DOI: 10.1126/sciadv.adk8521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 02/15/2024] [Indexed: 03/22/2024]
Abstract
The type I adenosine 5'-triphosphate (ATP)-binding cassette (ABC) transporter DppABCD is believed to be responsible for the import of exogenous heme as an iron source into the cytoplasm of the human pathogen Mycobacterium tuberculosis (Mtb). Additionally, this system is also known to be involved in the acquisition of tri- or tetra-peptides. Here, we report the cryo-electron microscopy structures of the dual-function Mtb DppABCD transporter in three forms, namely, the apo, substrate-bound, and ATP-bound states. The apo structure reveals an unexpected and previously uncharacterized assembly mode for ABC importers, where the lipoprotein DppA, a cluster C substrate-binding protein (SBP), stands upright on the translocator DppBCD primarily through its hinge region and N-lobe. These structural data, along with biochemical studies, reveal the assembly of DppABCD complex and the detailed mechanism of DppABCD-mediated transport. Together, these findings provide a molecular roadmap for understanding the transport mechanism of a cluster C SBP and its translocator.
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Affiliation(s)
- Tianyu Hu
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaolin Yang
- National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, Shenzhen 518112, China
| | - Yuanchen Zhu
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Fengjiang Liu
- Innovative Center for Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Xiuna Yang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Shanghai Clinical Research and Trial Center, Shanghai 201210, China
| | - Zhiqi Xiong
- Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
| | - Jingxi Liang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300353, China
| | - Zhenli Lin
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yuting Ran
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Luke W. Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Zihe Rao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, Shenzhen 518112, China
- Innovative Center for Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
- Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300353, China
| | - Bing Zhang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Shanghai Clinical Research and Trial Center, Shanghai 201210, China
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5
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Kerff F, Jourdan S, Francis IM, Deflandre B, Ribeiro Monteiro S, Stulanovic N, Loria R, Rigali S. Common scab disease: structural basis of elicitor recognition in pathogenic Streptomyces species. Microbiol Spectr 2023; 11:e0197523. [PMID: 37791952 PMCID: PMC10714786 DOI: 10.1128/spectrum.01975-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/21/2023] [Indexed: 10/05/2023] Open
Abstract
IMPORTANCE Common scab is a disease caused by a few Streptomyces species that affects important root and tuber crops including potato, beet, radish, and parsnip, resulting in major economic losses worldwide. In this work, we unveiled the molecular basis of host recognition by these pathogens by solving the structure of the sugar-binding protein CebE of Streptomyces scabiei in complex with cellotriose, the main elicitor of the pathogenic lifestyle of these bacteria. We further revealed that the signaling pathway from CebE-mediated transport of cellotriose is conserved in all pathogenic species except Streptomyces ipomoeae, which causes soft rot disease in sweet potatoes. Our work also provides the structural basis of the uptake of cellobiose and cellotriose in saprophytic Streptomyces species, the first step activating the expression of the enzymatic system degrading the most abundant polysaccharide on earth, cellulose.
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Affiliation(s)
- Frédéric Kerff
- InBioS–Center for Protein Engineering, Institut de Chimie B6a, University of Liège, Liège, Belgium
| | - Samuel Jourdan
- InBioS–Center for Protein Engineering, Institut de Chimie B6a, University of Liège, Liège, Belgium
| | - Isolde M. Francis
- Department of Biology, California State University, Bakersfield, California, USA
| | - Benoit Deflandre
- InBioS–Center for Protein Engineering, Institut de Chimie B6a, University of Liège, Liège, Belgium
| | - Silvia Ribeiro Monteiro
- InBioS–Center for Protein Engineering, Institut de Chimie B6a, University of Liège, Liège, Belgium
| | - Nudzejma Stulanovic
- InBioS–Center for Protein Engineering, Institut de Chimie B6a, University of Liège, Liège, Belgium
| | - Rosemary Loria
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Sébastien Rigali
- InBioS–Center for Protein Engineering, Institut de Chimie B6a, University of Liège, Liège, Belgium
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6
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Zhang L, Yu J, Zheng J, Wu L, Zhou X, Ban Y, Sun Y, Zhang H, Feng Y. A new l-serine binding orphan SerBP affects indole synthesis in Pantoea ananatis. J Basic Microbiol 2023; 63:1348-1360. [PMID: 37495561 DOI: 10.1002/jobm.202300165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/12/2023] [Accepted: 07/15/2023] [Indexed: 07/28/2023]
Abstract
Indole is traditionally known as a metabolite of l-tryptophan and now as an important signaling molecule in bacteria, however, the understanding of its upstream synthesis regulation is very limited. Pantoea ananatis YJ76, a predominant diazotrophic endophyte isolated from rice (Oryza sativa), can produce indole to regulate various physiological and biochemical behaviors. We constructed a mutant library of YJ76 using the mTn5 transposon insertion mutation method, from which an indole-deficient mutant was screened out. Via high-efficiency thermal asymmetric interlaced PCR (hiTAIL-PCR), the transposon was determined to be inserted in a gene (RefSeq: WP014605468.1) of unknown function that is highly conserved at the intraspecific level. Bioinformatics analysis implied that the protein (Protein ID: WP089517194.1) encoded by the mutant gene is most likely to be a new orphan substrate-binding protein (SBP) for amino acid ABC transporters. Amino acid supplement cultivation experiments and surface plasmon resonance revealed that the protein could bind to l-serine (KD = 6.149 × 10-5 M). Therefore, the SBP was named as SerBP. This is the first case that a SBP responds to l-serine ABC transports. As a precursor of indole synthesis, the transmembrane transported l-serine was directly correlated with indole signal production and the mutation of serBP gene weakened the resistance of YJ76 to antibiotics, alkali, heavy metals, and starvation. This study provided a new paradigm for exploring the upstream regulatory pathway for indole synthesis of bacteria.
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Affiliation(s)
- Lei Zhang
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Jiajia Yu
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Jing Zheng
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Liqing Wu
- Center of Advanced Measurement Science, National Institute of Metrology, Beijing, China
| | - Xinyi Zhou
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Yali Ban
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Yuanhao Sun
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Haotian Zhang
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Yongjun Feng
- School of Life Science, Beijing Institute of Technology, Beijing, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong, China
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7
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Ohnuma T, Tsujii J, Kataoka C, Yoshimoto T, Takeshita D, Lampela O, Juffer AH, Suginta W, Fukamizo T. Periplasmic chitooligosaccharide-binding protein requires a three-domain organization for substrate translocation. Sci Rep 2023; 13:20558. [PMID: 37996461 PMCID: PMC10667598 DOI: 10.1038/s41598-023-47253-y] [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: 07/04/2023] [Accepted: 11/10/2023] [Indexed: 11/25/2023] Open
Abstract
Periplasmic solute-binding proteins (SBPs) specific for chitooligosaccharides, (GlcNAc)n (n = 2, 3, 4, 5 and 6), are involved in the uptake of chitinous nutrients and the negative control of chitin signal transduction in Vibrios. Most translocation processes by SBPs across the inner membrane have been explained thus far by two-domain open/closed mechanism. Here we propose three-domain mechanism of the (GlcNAc)n translocation based on experiments using a recombinant VcCBP, SBP specific for (GlcNAc)n from Vibrio cholerae. X-ray crystal structures of unliganded or (GlcNAc)3-liganded VcCBP solved at 1.2-1.6 Å revealed three distinct domains, the Upper1, Upper2 and Lower domains for this protein. Molecular dynamics simulation indicated that the motions of the three domains are independent and that in the (GlcNAc)3-liganded state the Upper2/Lower interface fluctuated more intensively, compared to the Upper1/Lower interface. The Upper1/Lower interface bound two GlcNAc residues tightly, while the Upper2/Lower interface appeared to loosen and release the bound sugar molecule. The three-domain mechanism proposed here was fully supported by binding data obtained by thermal unfolding experiments and ITC, and may be applicable to other translocation systems involving SBPs belonging to the same cluster.
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Affiliation(s)
- Takayuki Ohnuma
- Department of Advanced Bioscience, Kindai University, 3327-204 Nakamachi, Nara, 631-8505, Japan.
- Agricultural Technology and Innovation Research Institute (ATIRI), Kindai University, 3327-204, Nakamachi, Nara, 631-8505, Japan.
| | - Jun Tsujii
- Department of Advanced Bioscience, Kindai University, 3327-204 Nakamachi, Nara, 631-8505, Japan
| | - Chikara Kataoka
- Department of Advanced Bioscience, Kindai University, 3327-204 Nakamachi, Nara, 631-8505, Japan
| | - Teruki Yoshimoto
- Department of Advanced Bioscience, Kindai University, 3327-204 Nakamachi, Nara, 631-8505, Japan
| | - Daijiro Takeshita
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba-Shi, Ibaraki, 305-8566, Japan
| | - Outi Lampela
- Biocenter Oulu, University of Oulu, P.O. Box 5000, FI-90014, Oulu, Finland
| | - André H Juffer
- Biocenter Oulu, University of Oulu, P.O. Box 5000, FI-90014, Oulu, Finland
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O.Box 5000, FI-90014, Oulu, Finland
| | - Wipa Suginta
- School of Biomolecular Science & Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley 555 Moo 1 Payupnai, Wangchan, Rayong, 21210, Thailand
| | - Tamo Fukamizo
- Department of Advanced Bioscience, Kindai University, 3327-204 Nakamachi, Nara, 631-8505, Japan.
- School of Biomolecular Science & Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley 555 Moo 1 Payupnai, Wangchan, Rayong, 21210, Thailand.
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8
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Michel F, Romero‐Romero S, Höcker B. Retracing the evolution of a modern periplasmic binding protein. Protein Sci 2023; 32:e4793. [PMID: 37788980 PMCID: PMC10601554 DOI: 10.1002/pro.4793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/20/2023] [Accepted: 09/22/2023] [Indexed: 10/05/2023]
Abstract
Investigating the evolution of structural features in modern multidomain proteins helps to understand their immense diversity and functional versatility. The class of periplasmic binding proteins (PBPs) offers an opportunity to interrogate one of the main processes driving diversification: the duplication and fusion of protein sequences to generate new architectures. The symmetry of their two-lobed topology, their mechanism of binding, and the organization of their operon structure led to the hypothesis that PBPs arose through a duplication and fusion event of a single common ancestor. To investigate this claim, we set out to reverse the evolutionary process and recreate the structural equivalent of a single-lobed progenitor using ribose-binding protein (RBP) as our model. We found that this modern PBP can be deconstructed into its lobes, producing two proteins that represent possible progenitor halves. The isolated halves of RBP are well folded and monomeric proteins, albeit with a lower thermostability, and do not retain the original binding function. However, the two entities readily form a heterodimer in vitro and in-cell. The x-ray structure of the heterodimer closely resembles the parental protein. Moreover, the binding function is fully regained upon formation of the heterodimer with a ligand affinity similar to that observed in the modern RBP. This highlights how a duplication event could have given rise to a stable and functional PBP-like fold and provides insights into how more complex functional structures can evolve from simpler molecular components.
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Affiliation(s)
- Florian Michel
- Department of BiochemistryUniversity of BayreuthBayreuthGermany
| | | | - Birte Höcker
- Department of BiochemistryUniversity of BayreuthBayreuthGermany
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9
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Wang C, Zhu WJ, Ding HT, Liu NH, Cao HY, Suo CL, Liu ZK, Zhang Y, Sun ML, Fu HH, Li CY, Chen XL, Zhang YZ, Wang P. Structural and molecular basis for urea recognition by Prochlorococcus. J Biol Chem 2023; 299:104958. [PMID: 37380083 PMCID: PMC10392092 DOI: 10.1016/j.jbc.2023.104958] [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: 02/16/2023] [Revised: 06/09/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Nitrogen (N) is an essential element for microbial growth and metabolism. The growth and reproduction of microorganisms in more than 75% of areas of the ocean are limited by N. Prochlorococcus is numerically the most abundant photosynthetic organism on the planet. Urea is an important and efficient N source for Prochlorococcus. However, how Prochlorococcus recognizes and absorbs urea still remains unclear. Prochlorococcus marinus MIT 9313, a typical Cyanobacteria, contains an ABC-type transporter, UrtABCDE, which may account for the transport of urea. Here, we heterologously expressed and purified UrtA, the substrate-binding protein of UrtABCDE, detected its binding affinity toward urea, and further determined the crystal structure of the UrtA/urea complex. Molecular dynamics simulations indicated that UrtA can alternate between "open" and "closed" states for urea binding. Based on structural and biochemical analyses, the molecular mechanism for urea recognition and binding was proposed. When a urea molecule is bound, UrtA undergoes a state change from open to closed surrounding the urea molecule, and the urea molecule is further stabilized by the hydrogen bonds supported by the conserved residues around it. Moreover, bioinformatics analysis showed that ABC-type urea transporters are widespread in bacteria and probably share similar urea recognition and binding mechanisms as UrtA from P. marinus MIT 9313. Our study provides a better understanding of urea absorption and utilization in marine bacteria.
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Affiliation(s)
- Chen Wang
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China; State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Wen-Jing Zhu
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China; State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Hai-Tao Ding
- Antarctic Great Wall Ecology National Observation and Research Station, Polar Research Institute of China, Shanghai, China
| | - Ning-Hua Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Hai-Yan Cao
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Chuan-Lei Suo
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Ze-Kun Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yi Zhang
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Mei-Ling Sun
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Hui-Hui Fu
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Chun-Yang Li
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China; Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yu-Zhong Zhang
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China; Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Peng Wang
- MOE Key Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.
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10
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Michel F, Shanmugaratnam S, Romero-Romero S, Höcker B. Structures of permuted halves of a modern ribose-binding protein. Acta Crystallogr D Struct Biol 2023; 79:40-49. [PMID: 36601806 PMCID: PMC9815098 DOI: 10.1107/s205979832201186x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 12/13/2022] [Indexed: 12/31/2022] Open
Abstract
Periplasmic binding proteins (PBPs) are a class of proteins that participate in the cellular transport of various ligands. They have been used as model systems to study mechanisms in protein evolution, such as duplication, recombination and domain swapping. It has been suggested that PBPs evolved from precursors half their size. Here, the crystal structures of two permuted halves of a modern ribose-binding protein (RBP) from Thermotoga maritima are reported. The overexpressed proteins are well folded and show a monomer-dimer equilibrium in solution. Their crystal structures show partially noncanonical PBP-like fold type I conformations with structural deviations from modern RBPs. One of the half variants forms a dimer via segment swapping, suggesting a high degree of malleability. The structural findings on these permuted halves support the evolutionary hypothesis that PBPs arose via a duplication event of a flavodoxin-like protein and further support a domain-swapping step that might have occurred during the evolution of the PBP-like fold, a process that is necessary to generate the characteristic motion of PBPs essential to perform their functions.
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Affiliation(s)
- Florian Michel
- Department of Biochemistry, University of Bayreuth, 95447 Bayreuth, Germany
| | | | | | - Birte Höcker
- Department of Biochemistry, University of Bayreuth, 95447 Bayreuth, Germany,Correspondence e-mail:
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Dutta A, Prasad Kanaujia S. MlaC belongs to a unique class of non-canonical substrate-binding proteins and follows a novel phospholipid-binding mechanism. J Struct Biol 2022; 214:107896. [PMID: 36084896 DOI: 10.1016/j.jsb.2022.107896] [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: 06/27/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 12/30/2022]
Abstract
The outer membrane (OM) of Gram-negative bacteria acts as a formidable barrier against a plethora of detrimental compounds owing to its asymmetric nature. This is because the OM possesses lipopolysaccharides (LPSs) in the outer leaflet and phospholipids (PLs) in the inner leaflet. The maintenance of lipid asymmetry (Mla) system is involved in preserving the distribution of PLs in OM. The periplasmic component of the system MlaC serves as the substrate-binding protein (SBP) that shuttles PLs between the inner and outer membranes. However, an in-depth report highlighting its mechanism of ligand binding is still lacking. This study reports the crystal structure of MlaC from Escherichia coli (EcMlaC) at a resolution of 2.5 Å in a quasi-open state, complexed with PL. The structural analysis reveals that EcMlaC and orthologs comprise two major domains, viz. nuclear transport factor 2-like (NTF2-like) and phospholipid-binding protein (PBP). Each domain can be further divided into two subdomains arranged in a discontinuous fashion. This study further reveals that EcMlaC is polyspecific in nature and follows a reverse mechanism of the opening of the substrate-binding site during the ligand binding. Furthermore, MlaC can bind two PLs by forming subsites in the binding pocket. These findings, altogether, have led to the proposition of the unique "segmented domain movement" mechanism of PL binding, not reported for any known SBP to date. Further, unlike typical SBPs, MlaC has originated from a cystatin-like fold. Overall, this study establishes MlaC to be a non-canonical SBP with a unique ligand-binding mechanism.
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Affiliation(s)
- Angshu Dutta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati - 781039, Assam, India
| | - Shankar Prasad Kanaujia
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati - 781039, Assam, India.
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Akbari MS, Doran KS, Burcham LR. Metal Homeostasis in Pathogenic Streptococci. Microorganisms 2022; 10:microorganisms10081501. [PMID: 35893559 PMCID: PMC9331361 DOI: 10.3390/microorganisms10081501] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 02/05/2023] Open
Abstract
Streptococcus spp. are an important genus of Gram-positive bacteria, many of which are opportunistic pathogens that are capable of causing invasive disease in a wide range of populations. Metals, especially transition metal ions, are an essential nutrient for all organisms. Therefore, to survive across dynamic host environments, Streptococci have evolved complex systems to withstand metal stress and maintain metal homeostasis, especially during colonization and infection. There are many different types of transport systems that are used by bacteria to import or export metals that can be highly specific or promiscuous. Focusing on the most well studied transition metals of zinc, manganese, iron, nickel, and copper, this review aims to summarize the current knowledge of metal homeostasis in pathogenic Streptococci, and their role in virulence.
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