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Mix LT, Hara M, Fuzell J, Kumauchi M, Kaledhonkar S, Xie A, Hoff WD, Larsen DS. Not All Photoactive Yellow Proteins Are Built Alike: Surprises and Insights into Chromophore Photoisomerization, Protonation, and Thermal Reisomerization of the Photoactive Yellow Protein Isolated from Salinibacter ruber. J Am Chem Soc 2021; 143:19614-19628. [PMID: 34780163 DOI: 10.1021/jacs.1c08910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We demonstrate that the Halorhodospira halophila (Hhal) photoactive yellow protein (PYP) is not representative of the greater PYP family. The photodynamics of the PYP isolated from Salinibacter ruber (Srub) is characterized with a comprehensive range of spectroscopic techniques including ultrafast transient absorption, photostationary light titrations, Fourier transform infrared, and cryokinetics spectroscopies. We demonstrate that the dark-adapted pG state consists of two subpopulations differing in the protonation state of the chromophore and that both are photoactive, with the protonated species undergoing excited-state proton transfer. However, the primary I0 photoproduct observed in the Hhal PYP photocycle is absent in the Srub PYP photodynamics, which indicates that this intermediate, while important in Hhal photodynamics, is not a critical intermediate in initiating all PYP photocycles. The excited-state lifetime of Srub PYP is the longest of any PYP resolved to date (∼30 ps), which we ascribe to the more constrained chromophore binding pocket of Srub PYP and the absence of the critical Arg52 residue found in Hhal PYP. The final stage of the Srub PYP photocycle involves the slowest known thermal dark reversion of a PYP (∼40 min vs 350 ms in Hhal PYP). This property allowed the characterization of a pH-dependent equilibrium between the light-adapted pB state with a protonated cis chromophore and a newly resolved pG' intermediate with a deprotonated cis chromophore and pG-like protein conformation. This result demonstates that protein conformational changes and chromophore deprotonation precede chromophore reisomerization during the thermal recovery of the PYP photocycle.
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Affiliation(s)
- L Tyler Mix
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Miwa Hara
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Jack Fuzell
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Masato Kumauchi
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Sandip Kaledhonkar
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Aihua Xie
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, United States.,Center for Advanced Infrared Biology College of Arts and Sciences, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Wouter D Hoff
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74078, United States.,Center for Advanced Infrared Biology College of Arts and Sciences, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Delmar S Larsen
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
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Kaledhonkar S, Fu Z, Caban K, Li W, Chen B, Sun M, Gonzalez RL, Frank J. Late steps in bacterial translation initiation visualized using time-resolved cryo-EM. Nature 2019; 570:400-404. [PMID: 31108498 PMCID: PMC7060745 DOI: 10.1038/s41586-019-1249-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 05/08/2019] [Indexed: 12/02/2022]
Abstract
The initiation of bacterial translation involves the tightly regulated joining of the 50S ribosomal subunit to an initiator transfer RNA (fMet-tRNAfMet)-containing 30S ribosomal initiation complex to form a 70S initiation complex, which subsequently matures into a 70S elongation-competent complex. Rapid and accurate formation of the 70S initiation complex is promoted by initiation factors, which must dissociate from the 30S initiation complex before the resulting 70S elongation-competent complex can begin the elongation of translation1. Although comparisons of the structures of the 30S2-5 and 70S4,6-8 initiation complexes have revealed that the ribosome, initiation factors and fMet-tRNAfMet can acquire different conformations in these complexes, the timing of conformational changes during formation of the 70S initiation complex, the structures of any intermediates formed during these rearrangements, and the contributions that these dynamics might make to the mechanism and regulation of initiation remain unknown. Moreover, the absence of a structure of the 70S elongation-competent complex formed via an initiation-factor-catalysed reaction has precluded an understanding of the rearrangements to the ribosome, initiation factors and fMet-tRNAfMet that occur during maturation of a 70S initiation complex into a 70S elongation-competent complex. Here, using time-resolved cryogenic electron microscopy9, we report the near-atomic-resolution view of how a time-ordered series of conformational changes drive and regulate subunit joining, initiation factor dissociation and fMet-tRNAfMet positioning during formation of the 70S elongation-competent complex. Our results demonstrate the power of time-resolved cryogenic electron microscopy to determine how a time-ordered series of conformational changes contribute to the mechanism and regulation of one of the most fundamental processes in biology.
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MESH Headings
- Cryoelectron Microscopy
- Escherichia coli/chemistry
- Escherichia coli/metabolism
- Escherichia coli/ultrastructure
- Peptide Chain Elongation, Translational
- Peptide Chain Initiation, Translational
- Protein Conformation
- Ribosome Subunits, Large, Bacterial/metabolism
- Ribosome Subunits, Large, Bacterial/ultrastructure
- Ribosome Subunits, Small, Bacterial/metabolism
- Ribosome Subunits, Small, Bacterial/ultrastructure
- Ribosomes/chemistry
- Ribosomes/metabolism
- Ribosomes/ultrastructure
- Time Factors
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Affiliation(s)
- Sandip Kaledhonkar
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA
| | - Ziao Fu
- Integrated Program in Cellular, Molecular and Biophysical Studies, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Kelvin Caban
- Department of Chemistry, Columbia University, New York, NY, USA
| | - Wen Li
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA
| | - Bo Chen
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA
| | - Ming Sun
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia University, New York, NY, USA.
| | - Joachim Frank
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA.
- Department of Biological Sciences, Columbia University, New York, NY, USA.
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Caban K, Pavlov M, Kaledhonkar S, Fu Z, Frank J, Ehrenberg M, Gonzalez RL. The Structural Basis for Initiation Factor 2 Activation during Translation Initiation. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Abstract
With the advent of direct electron detectors, cryo-EM has become a popular choice for molecular structure determination. Among its advantages over X-ray crystallography are (1) no need for crystals, (2) much smaller sample volumes, and (3) the ability to determine multiple structures or conformations coexisting in one sample. In principle, kinetic experiments can be done using standard cryo-EM, but mixing and freezing grids require several seconds. However, many biological processes are much faster than that time scale, and the ensuing short-lived states of the molecules cannot be captured. Here, we lay out a detailed protocol for how to capture such intermediate states on the millisecond time scale with time-resolved cryo-EM.
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Affiliation(s)
- Sandip Kaledhonkar
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, 10032, NY, USA
| | - Ziao Fu
- Integrated Program in Cellular, Molecular and Biomolecular Studies, Columbia University College of Physicians and Surgeons, New York, 10032, NY, USA
| | - Howard White
- Physiological Sciences, Eastern Virginia Medical School, Norfolk, 23507, VA, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, 10032, NY, USA. .,Department of Biological Sciences, Columbia University, New York, 10027, NY, USA.
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Feng X, Fu Z, Kaledhonkar S, Jia Y, Shah B, Jin A, Liu Z, Sun M, Chen B, Grassucci RA, Ren Y, Jiang H, Frank J, Lin Q. A Fast and Effective Microfluidic Spraying-Plunging Method for High-Resolution Single-Particle Cryo-EM. Structure 2017; 25:663-670.e3. [PMID: 28286002 DOI: 10.1016/j.str.2017.02.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/10/2017] [Accepted: 02/10/2017] [Indexed: 11/17/2022]
Abstract
We describe a spraying-plunging method for preparing cryoelectron microscopy (cryo-EM) grids with vitreous ice of controllable, highly consistent thickness using a microfluidic device. The new polydimethylsiloxane (PDMS)-based sprayer was tested with apoferritin. We demonstrate that the structure can be solved to high resolution with this method of sample preparation. Besides replacing the conventional pipetting-blotting-plunging method, one of many potential applications of the new sprayer is in time-resolved cryo-EM, as part of a PDMS-based microfluidic reaction channel to study short-lived intermediates on the timescale of 10-1,000 ms.
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Affiliation(s)
- Xiangsong Feng
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA; School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Ziao Fu
- Integrated Program in Cellular, Molecular, and Biophysical Studies, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - Sandip Kaledhonkar
- Department of Biochemistry and Molecular Biophysics, Columbia University New York, NY 10027, USA
| | - Yuan Jia
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
| | - Binita Shah
- Department of Biological Sciences, Barnard College, New York, NY 10027, USA
| | - Amy Jin
- Department of Biochemistry and Molecular Biophysics, Columbia University New York, NY 10027, USA
| | - Zheng Liu
- Department of Biochemistry and Molecular Biophysics, Columbia University New York, NY 10027, USA
| | - Ming Sun
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Bo Chen
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Robert A Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Yukun Ren
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Hongyuan Jiang
- School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University New York, NY 10027, USA; Department of Biological Sciences, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
| | - Qiao Lin
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA.
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Chen B, Kaledhonkar S, Sun M, Shen B, Lu Z, Barnard D, Lu TM, Gonzalez RL, Frank J. Structural dynamics of ribosome subunit association studied by mixing-spraying time-resolved cryogenic electron microscopy. Structure 2015; 23:1097-105. [PMID: 26004440 DOI: 10.1016/j.str.2015.04.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 03/16/2015] [Accepted: 04/05/2015] [Indexed: 11/25/2022]
Abstract
Ribosomal subunit association is a key checkpoint in translation initiation but its structural dynamics are poorly understood. Here, we used a recently developed mixing-spraying, time-resolved, cryogenic electron microscopy (cryo-EM) method to study ribosomal subunit association in the sub-second time range. We have improved this method and increased the cryo-EM data yield by tenfold. Pre-equilibrium states of the association reaction were captured by reacting the mixture of ribosomal subunits for 60 ms and 140 ms. We also identified three distinct ribosome conformations in the associated ribosomes. The observed proportions of these conformations are the same in these two time points, suggesting that ribosomes equilibrate among the three conformations within less than 60 ms upon formation. Our results demonstrate that the mixing-spraying method can capture multiple states of macromolecules during a sub-second reaction. Other fast processes, such as translation initiation, decoding, and ribosome recycling, are amenable to study with this method.
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Affiliation(s)
- Bo Chen
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Sandip Kaledhonkar
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Ming Sun
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Bingxin Shen
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Zonghuan Lu
- Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - David Barnard
- Wadsworth Center, Albany, New York State Department of Health, Albany, NY 12201, USA
| | - Toh-Ming Lu
- Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Joachim Frank
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Biological Sciences, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
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Kaledhonkar S, Hara M, Stalcup TP, Xie A, Hoff WD. Strong ionic hydrogen bonding causes a spectral isotope effect in photoactive yellow protein. Biophys J 2014; 105:2577-85. [PMID: 24314088 DOI: 10.1016/j.bpj.2013.10.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 10/07/2013] [Accepted: 10/16/2013] [Indexed: 10/25/2022] Open
Abstract
Standard hydrogen bonds are of great importance for protein structure and function. Ionic hydrogen bonds often are significantly stronger than standard hydrogen bonds and exhibit unique properties, but their role in proteins is not well understood. We report that hydrogen/deuterium exchange causes a redshift in the visible absorbance spectrum of photoactive yellow protein (PYP). We expand the range of interpretable isotope effects by assigning this spectral isotope effect (SIE) to a functionally important hydrogen bond at the active site of PYP. The inverted sign and extent of this SIE is explained by the ionic nature and strength of this hydrogen bond. These results show the relevance of ionic hydrogen bonding for protein active sites, and reveal that the inverted SIE is a novel, to our knowledge, tool to probe ionic hydrogen bonds. Our results support a classification of hydrogen bonds that distinguishes the properties of ionic hydrogen bonds from those of both standard and low barrier hydrogen bonds, and show how this classification helps resolve a recent debate regarding active site hydrogen bonding in PYP.
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Kumauchi M, Kaledhonkar S, Philip AF, Wycoff J, Hara M, Li Y, Xie A, Hoff WD. A conserved helical capping hydrogen bond in PAS domains controls signaling kinetics in the superfamily prototype photoactive yellow protein. J Am Chem Soc 2011; 132:15820-30. [PMID: 20954744 DOI: 10.1021/ja107716r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PAS domains form a divergent protein superfamily with more than 20 000 members that perform a wide array of sensing and regulatory functions in all three domains of life. Only nine residues are well-conserved in PAS domains, with an Asn residue at the start of α-helix 3 showing the strongest conservation. The molecular functions of these nine conserved residues are unknown. We use static and time-resolved visible and FTIR spectroscopy to investigate receptor activation in the photosensor photoactive yellow protein (PYP), a PAS domain prototype. The N43A and N43S mutants allow an investigation of the role of side-chain hydrogen bonding at this conserved position. The mutants exhibit a blue-shifted visible absorbance maximum and up-shifted chromophore pK(a). Disruption of the hydrogen bonds in N43A PYP causes both a reduction in protein stability and a 3400-fold increase in the lifetime of the signaling state of this photoreceptor. A significant part of this increase in lifetime can be attributed to the helical capping interaction of Asn43. This extends the known importance of helical capping for protein structure to regulating functional protein kinetics. A model for PYP activation has been proposed in which side-chain hydrogen bonding of Asn43 is critical for relaying light-induced conformational changes. However, FTIR spectroscopy shows that both Asn43 mutants retain full allosteric transmission of structural changes. Analysis of 30 available high-resolution structures of PAS domains reveals that the side-chain hydrogen bonding of residue 43 but not residue identity is highly conserved and suggests that its helical cap affects signaling kinetics in other PAS domains.
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Affiliation(s)
- Masato Kumauchi
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74078, United States
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van der Horst MA, Stalcup TP, Kaledhonkar S, Kumauchi M, Hara M, Xie A, Hellingwerf KJ, Hoff WD. Locked chromophore analogs reveal that photoactive yellow protein regulates biofilm formation in the deep sea bacterium Idiomarina loihiensis. J Am Chem Soc 2010; 131:17443-51. [PMID: 19891493 DOI: 10.1021/ja9057103] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Idiomarina loihiensis is a heterotrophic deep sea bacterium with no known photobiology. We show that light suppresses biofilm formation in this organism. The genome of I. loihiensis encodes a single photoreceptor protein: a homologue of photoactive yellow protein (PYP), a blue light receptor with photochemistry based on trans to cis isomerization of its p-coumaric acid (pCA) chromophore. The addition of trans-locked pCA to I. loihiensis increases biofilm formation, whereas cis-locked pCA decreases it. This demonstrates that the PYP homologue regulates biofilm formation in I. loihiensis, revealing an unexpected functional versatility in the PYP family of photoreceptors. These results imply that I. loihiensis thrives not only in the deep sea but also near the water surface and provide an example of genome-based discovery of photophysiological responses. The use of locked pCA analogs is a novel and generally applicable pharmacochemical tool to study the in vivo role of PYPs irrespective of genetic accessibility. Heterologously produced PYP from I. loihiensis (Il PYP) absorbs maximally at 446 nm and has a pCA pK(a) of 3.4. Photoexcitation triggers the formation of a pB signaling state that decays with a time constant of 0.3 s. FTIR difference signals at 1726 and 1497 cm(-1) reveal that active-site proton transfer during the photocycle is conserved in Il PYP. It has been proposed that a correlation exists between the lifetime of a photoreceptor signaling state and the time scale of the biological response that it regulates. The data presented here provide an example of a protein with a rapid photocycle that regulates a slow biological response.
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Affiliation(s)
- Michael A van der Horst
- Department of Molecular Microbial Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, The Netherlands
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Kaledhonkar S, Kelemen L, Thubagere A, Li Y, Xie A. Impact of Hofmeister Salts on Structural Dynamics of Photoactive Yellow Protein. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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