Protein crystallization: Eluding the bottleneck of X-ray crystallography

Joshua Holcomb; Nicholas Spellmon; Yingxue Zhang; Maysaa Doughan; Chunying Li; Zhe Yang; Joshua Holcomb; Nicholas Spellmon; Yingxue Zhang; Maysaa Doughan; Chunying Li; Zhe Yang

doi:10.3934/biophy.2017.4.557

AIMS Biophysics

2017, Volume 4, Issue 4: 557-575. doi: 10.3934/biophy.2017.4.557

Previous Article Next Article

Review

Protein crystallization: Eluding the bottleneck of X-ray crystallography

1.
Department of Microbiology, Immunology, and Biochemistry, Wayne State University School of Medicine, Detroit, MI, USA
2.
Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA, USA

Received: 03 August 2017 Accepted: 21 September 2017 Published: 26 September 2017

To date, X-ray crystallography remains the gold standard for the determination of macromolecular structure and protein substrate interactions. However, the unpredictability of obtaining a protein crystal remains the limiting factor and continues to be the bottleneck in determining protein structures. A vast amount of research has been conducted in order to circumvent this issue with limited success. No single method has proven to guarantee the crystallization of all proteins. However, techniques using antibody fragments, lipids, carrier proteins, and even mutagenesis of crystal contacts have been implemented to increase the odds of obtaining a crystal with adequate diffraction. In addition, we review a new technique using the scaffolding ability of PDZ domains to facilitate nucleation and crystal lattice formation. Although in its infancy, such technology may be a valuable asset and another method in the crystallography toolbox to further the chances of crystallizing problematic proteins.
- protein crystallization,
- X-ray crystallography,
- carrier mediated crystallization,
- PDZ scaffold mediated crystallization
Citation: Joshua Holcomb, Nicholas Spellmon, Yingxue Zhang, Maysaa Doughan, Chunying Li, Zhe Yang. Protein crystallization: Eluding the bottleneck of X-ray crystallography[J]. AIMS Biophysics, 2017, 4(4): 557-575. doi: 10.3934/biophy.2017.4.557

Related Papers:

Abstract

To date, X-ray crystallography remains the gold standard for the determination of macromolecular structure and protein substrate interactions. However, the unpredictability of obtaining a protein crystal remains the limiting factor and continues to be the bottleneck in determining protein structures. A vast amount of research has been conducted in order to circumvent this issue with limited success. No single method has proven to guarantee the crystallization of all proteins. However, techniques using antibody fragments, lipids, carrier proteins, and even mutagenesis of crystal contacts have been implemented to increase the odds of obtaining a crystal with adequate diffraction. In addition, we review a new technique using the scaffolding ability of PDZ domains to facilitate nucleation and crystal lattice formation. Although in its infancy, such technology may be a valuable asset and another method in the crystallography toolbox to further the chances of crystallizing problematic proteins.

References

[1]	Hünefeld FL (1840) Der Chemismus in der thierischen Organisation : physiologisch-chemische Untersuchungen der materiellen Veränderungen oder des Bildungslebens im thierischen Organismus, insbesondere des Blutbildungsprocesses, der Natur der Blutkörperchen und ihrer Kernchen: ein Beitrag zur Physiologie und Heilmittellehre.
[2]	Giege R (2013) A historical perspective on protein crystallization from 1840 to the present day. FEBS J 280: 6456–6497. doi: 10.1111/febs.12580
[3]	McPherson A, Gavira JA (2014) Introduction to protein crystallization. Acta Crystallogr F 70: 2–20.
[4]	Funke O (1851) Über das Milzvenenblut. Z Rat Medicin 1: 172–218.
[5]	Ritthausen H (1872) Die Eiweisskörper der Getreidearten, Hülsenfrüchte und Ölsamen. Beiträge zur Physiologie der Samen der Kulturgewachese, der Nahrungs- und Futtermitel, Bonn.
[6]	Osborne TB (1892) Crystallized vegetable proteids. Amer Chem J 14: 662–689.
[7]	Kepler J (1611) Ioannis Kepleris Strena, seu, De niue sexangula [microform]. Francofvrti ad Moenvm: Apud Godefridum Tampach, 24.
[8]	Bragg WH, Bragg WL (1913) The reflection of X-rays by crystals. P Roy Soc A 88: 428–438. doi: 10.1098/rspa.1913.0040
[9]	Kendrew JC, Bodo G, Dintzis HM, et al. (1958) A three-dimensional model of the myoglobin molecule obtained by x-ray analysis. Nature 181: 662–666. doi: 10.1038/181662a0
[10]	Blake CC, Koenig DF, Mair GA, et al. (1965) Structure of hen egg-white lysozyme: A three-dimensional Fourier synthesis at 2 Angstrom resolution. Nature 206: 757–761. doi: 10.1038/206757a0
[11]	Perutz MF, Rossmann MG, Cullis AF, et al. (1960) Structure of haemoglobin: a three-dimensional Fourier synthesis at 5.5-A. resolution, obtained by X-ray analysis. Nature 185: 416–422.
[12]	Chayen NE, Saridakis E (2008) Protein crystallization: from purified protein to diffraction-quality crystal. Nat Methods 5: 147–153. doi: 10.1038/nmeth.f.203
[13]	Sleutel M, Van Driessche AE (2014) Role of clusters in nonclassical nucleation and growth of protein crystals. Proc Natl Acad Sci USA 111: E546–E553. doi: 10.1073/pnas.1309320111
[14]	Gavira JA (2016) Current trends in protein crystallization. Arch Biochem Biophys 602: 3–11. doi: 10.1016/j.abb.2015.12.010
[15]	Rayment I (2002) Small-scale batch crystallization of proteins revisited. Structure 10: 147–151. doi: 10.1016/S0969-2126(02)00711-6
[16]	Chayen NE, Shaw Stewart PD, Maeder DL, et al. (1990) An automated system for micro-batch protein crystallization and screening. J Appl Crystallogr 23: 297–302. doi: 10.1107/S0021889890003260
[17]	Mahon BP, Kurian JJ, Lomelino CL, et al. (2016) Microbatch mixing: "Shaken not stirred", a method for macromolecular microcrystal production for serial crystallography. Cryst Growth Des 16: 6214–6221. doi: 10.1021/acs.cgd.6b00643
[18]	Otalora F, Gavira JA, Ng JD, et al. (2009) Counterdiffusion methods applied to protein crystallization. Prog Biophys Mol Bio 101: 26–37. doi: 10.1016/j.pbiomolbio.2009.12.004
[19]	Gavira JA, Toh D, Lopez-Jaramillo J, et al. (2002) Ab initio crystallographic structure determination of insulin from protein to electron density without crystal handling. Acta Crystallogr D 58: 1147–1154. doi: 10.1107/S0907444902006959
[20]	Trakhanov S, Quiocho FA (1995) Influence of divalent cations in protein crystallization. Protein Sci 4: 1914–1919. doi: 10.1002/pro.5560040925
[21]	Cudney R, Patel S, Weisgraber K, et al. (1994) Screening and optimization strategies for macromolecular crystal growth. Acta Crystallogr D 50: 414–423.
[22]	Tomcova I, Branca RM, Bodo G, et al. (2006) Cross-crystallization method used for the crystallization and preliminary diffraction analysis of a novel di-haem cytochrome c4. Acta Crystallogr F 62: 820–824.
[23]	Sirinupong N, Brunzelle J, Ye J, et al. (2010) Crystal structure of cardiac-specific histone methyltransferase SmyD1 reveals unusual active site architecture. J Biol Chem 285: 40635–40644. doi: 10.1074/jbc.M110.168187
[24]	Hoeppner A, Schmitt L, Smits SHJ (2013) Proteins and their Ligands: Their Importance and How to Crystallize Them, In: Ferreira SO, Editor, Advanced Topics on Crystal Growth, Rijeka: InTech.
[25]	Vedadi M, Niesen FH, Allali-Hassani A, et al. (2006) Chemical screening methods to identify ligands that promote protein stability, protein crystallization, and structure determination. Proc Natl Acad Sci USA 103: 15835–15840. doi: 10.1073/pnas.0605224103
[26]	Dale GE, Oefner C, D'Arcy A (2003) The protein as a variable in protein crystallization. J Struct Biol 142: 88–97. doi: 10.1016/S1047-8477(03)00041-8
[27]	Marsden RL, McGuffin LJ, Jones DT (2002) Rapid protein domain assignment from amino acid sequence using predicted secondary structure. Protein Sci 11: 2814–2824.
[28]	Smyth DR, Mrozkiewicz MK, McGrath WJ, et al. (2003) Crystal structures of fusion proteins with large-affinity tags. Protein Sci 12: 1313–1322. doi: 10.1110/ps.0243403
[29]	Miyazaki S, Kuroda Y, Yokoyama S (2002) Characterization and prediction of linker sequences of multi-domain proteins by a neural network. J Struct Funct Genomics 2: 37–51. doi: 10.1023/A:1014418700858
[30]	Milburn MV, Prive GG, Milligan DL, et al. (1991) Three-dimensional structures of the ligand-binding domain of the bacterial aspartate receptor with and without a ligand. Science 254: 1342–1347. doi: 10.1126/science.1660187
[31]	Yeh JI, Biemann HP, Prive GG, et al. (1996) High-resolution structures of the ligand binding domain of the wild-type bacterial aspartate receptor. J Mol Biol 262: 186–201. doi: 10.1006/jmbi.1996.0507
[32]	Dale GE, Kostrewa D, Gsell B, et al. (1999) Crystal engineering: deletion mutagenesis of the 24 kDa fragment of the DNA gyrase B subunit from Staphylococcus aureus. Acta Crystallogr D 55: 1626–1629. doi: 10.1107/S0907444999008227
[33]	Longenecker KL, Garrard SM, Sheffield PJ, et al. (2001) Protein crystallization by rational mutagenesis of surface residues: Lys to Ala mutations promote crystallization of RhoGDI. Acta Crystallogr D 57: 679–688. doi: 10.1107/S0907444901003122
[34]	Lawson DM, Artymiuk PJ, Yewdall SJ, et al. (1991) Solving the structure of human H ferritin by genetically engineering intermolecular crystal contacts. Nature 349: 541–544. doi: 10.1038/349541a0
[35]	McElroy HE, Sisson GW, Schoettlin WE, et al. (1992) Studies on engineering crystallizability by mutation of surface residues of human thymidylate synthase. J Cryst Growth 122: 265–272. doi: 10.1016/0022-0248(92)90255-H
[36]	Zhang XJ, Wozniak JA, Matthews BW (1995) Protein flexibility and adaptability seen in 25 crystal forms of T4 lysozyme. J Mol Biol 250: 527–552. doi: 10.1006/jmbi.1995.0396
[37]	Zhang F, Basinski MB, Beals JM, et al. (1997) Crystal structure of the obese protein leptin-E100. Nature 387: 206–209. doi: 10.1038/387206a0
[38]	Walter TS, Meier C, Assenberg R, et al. (2006) Lysine methylation as a routine rescue strategy for protein crystallization. Structure 14: 1617–1622. doi: 10.1016/j.str.2006.09.005
[39]	Rypniewski WR, Holden HM, Rayment I (1993) Structural consequences of reductive methylation of lysine residues in hen egg white lysozyme: an X-ray analysis at 1.8-A resolution. Biochemistry 32: 9851–9858.
[40]	Sachdev D, Chirgwin JM (2000) Fusions to maltose-binding protein: control of folding and solubility in protein purification. Method Enzymol 326: 312–321. doi: 10.1016/S0076-6879(00)26062-X
[41]	LaVallie ER, Lu Z, Diblasio-Smith EA, et al. (2000) Thioredoxin as a fusion partner for production of soluble recombinant proteins in Escherichia coli. Method Enzymol 326: 322–340. doi: 10.1016/S0076-6879(00)26063-1
[42]	Skerra A, Schmidt TG (2000) Use of the Strep-Tag and streptavidin for detection and purification of recombinant proteins. Method Enzymol 326: 271–304. doi: 10.1016/S0076-6879(00)26060-6
[43]	Smith DB (2000) Generating fusions to glutathione S-transferase for protein studies. Method Enzymol 326: 254–270. doi: 10.1016/S0076-6879(00)26059-X
[44]	Stevens RC (2000) Design of high-throughput methods of protein production for structural biology. Structure 8: R177–R185. doi: 10.1016/S0969-2126(00)00193-3
[45]	Edwards AM, Arrowsmith CH, Christendat D, et al. (2000) Protein production: feeding the crystallographers and NMR spectroscopists. Nat Struct Mol Biol 7: 970–972. doi: 10.1038/80751
[46]	Braun P, Hu Y, Shen B, et al. (2002) Proteome-scale purification of human proteins from bacteria. Proc Natl Acad Sci USA 99: 2654–2659. doi: 10.1073/pnas.042684199
[47]	Hammarstrom M, Hellgren N, Berg SVD, et al. (2002) Rapid screening for improved solubility of small human proteins produced as fusion proteins in Escherichia coli. Protein Sci 11: 313–321.
[48]	Shih YP, Kung WM, Chen JC, et al. (2002) High-throughput screening of soluble recombinant proteins. Protein Sci 11: 1714–1719.
[49]	Malakhov MP, Mattern MR, Malakhova OA, et al. (2004) SUMO fusions and SUMO-specific protease for efficient expression and purification of proteins. J Struct Funct Genomics 5: 75–86.
[50]	Center RJ, Kobe B, Wilson KA, et al. (1998) Crystallization of a trimeric human T cell leukemia virus type 1 gp21 ectodomain fragment as a chimera with maltose-binding protein. Protein Sci 7: 1612–1619. doi: 10.1002/pro.5560070715
[51]	Carter AP, Cho C, Jin L, et al. (2011) Crystal structure of the dynein motor domain. Science 331: 1159–1165. doi: 10.1126/science.1202393
[52]	Schmidt H, Gleave ES, Carter AP (2012) Insights into dynein motor domain function from a 3.3-A crystal structure. Nat Struct Mol Biol 19: 492–497. doi: 10.1038/nsmb.2272
[53]	Kovari LC, Momany C, Rossmann MG (1995) The use of antibody fragments for crystallization and structure determinations. Structure 3: 1291–1293. doi: 10.1016/S0969-2126(01)00266-0
[54]	Prongay AJ, Smith TJ, Rossmann MG, et al. (1990) Preparation and crystallization of a human immunodeficiency virus p24-Fab complex. Proc Natl Acad Sci USA 87: 9980–9984. doi: 10.1073/pnas.87.24.9980
[55]	Hunte C, Michel H (2002) Crystallisation of membrane proteins mediated by antibody fragments. Curr Opin Struc Biol 12: 503–508. doi: 10.1016/S0959-440X(02)00354-8
[56]	Waugh DS (2016) Crystal structures of MBP fusion proteins. Protein Sci 25: 559–571. doi: 10.1002/pro.2863
[57]	Spurlino JC, Lu GY, Quiocho FA (1991) The 2.3-A resolution structure of the maltose- or maltodextrin-binding protein, a primary receptor of bacterial active transport and chemotaxis. J Biol Chem 266: 5202–5219.
[58]	Sharff AJ, Rodseth LE, Spurlino JC, et al. (1992) Crystallographic evidence of a large ligand-induced hinge-twist motion between the two domains of the maltodextrin binding protein involved in active transport and chemotaxis. Biochemistry 31: 10657–10663. doi: 10.1021/bi00159a003
[59]	Matsumoto S, Shimada A, Kohda D (2013) Crystal structure of the C-terminal globular domain of the third paralog of the Archaeoglobus fulgidus oligosaccharyltransferases. BMC Struct Biol 13: 11. doi: 10.1186/1472-6807-13-11
[60]	Cherry AL, Finta C, Karlstrom M, et al. (2013) Structural basis of SUFU-GLI interaction in human Hedgehog signalling regulation. Acta Crystallogr D 69: 2563–2579. doi: 10.1107/S0907444913028473
[61]	Moon AF, Mueller GA, Zhong X, et al. (2010) A synergistic approach to protein crystallization: combination of a fixed-arm carrier with surface entropy reduction. Protein Sci 19: 901–913.
[62]	Kobe B, Center RJ, Kemp BE, et al. (1999) Crystal structure of human T cell leukemia virus type 1 gp21 ectodomain crystallized as a maltose-binding protein chimera reveals structural evolution of retroviral transmembrane proteins. Proc Natl Acad Sci USA 96: 4319–4324. doi: 10.1073/pnas.96.8.4319
[63]	Kuge M, Fujii Y, Shimizu T, et al. (1997) Use of a fusion protein to obtain crystals suitable for X-ray analysis: crystallization of a GST-fused protein containing the DNA-binding domain of DNA replication-related element-binding factor, DREF. Protein Sci 6: 1783–1786. doi: 10.1002/pro.5560060822
[64]	Lally JM, Newman RH, Knowles PP, et al. (1998) Crystallization of an intact GST-estrogen receptor hormone binding domain fusion protein. Acta Crystallogr D 54: 423–426. doi: 10.1107/S0907444997011086
[65]	Jiang Y, Sirinupong N, Brunzelle J, et al. (2011) Crystal structures of histone and p53 methyltransferase SmyD2 reveal a conformational flexibility of the autoinhibitory C-terminal domain. PLoS One 6: e21640. doi: 10.1371/journal.pone.0021640
[66]	Jiang Y, Trescott L, Holcomb J, et al. (2014) Structural insights into estrogen receptor alpha methylation by histone methyltransferase SMYD2, a cellular event implicated in estrogen signaling regulation. J Mol Biol 426: 3413–3425. doi: 10.1016/j.jmb.2014.02.019
[67]	Sirinupong N, Brunzelle J, Doko E, et al. (2011) Structural insights into the autoinhibition and posttranslational activation of histone methyltransferase SmyD3. J Mol Biol 406: 149–159. doi: 10.1016/j.jmb.2010.12.014
[68]	Heyman B (1996) Complement and Fc-receptors in regulation of the antibody response. Immunol Lett 54: 195–199. doi: 10.1016/S0165-2478(96)02672-7
[69]	Putnam FW, Liu YS, Low TL (1979) Primary structure of a human IgA1 immunoglobulin. IV. Streptococcal IgA1 protease, digestion, Fab and Fc fragments, and the complete amino acid sequence of the alpha 1 heavy chain. J Biol Chem 254: 2865–2874.
[70]	Venturi M, Hunte C (2003) Monoclonal antibodies for the structural analysis of the Na+/H+ antiporter NhaA from Escherichia coli. BBA-Biomembranes 1610: 46–50. doi: 10.1016/S0005-2736(02)00713-7
[71]	Lesk AM, Chothia C (1988) Elbow motion in the immunoglobulins involves a molecular ball-and-socket joint. Nature 335: 188–190. doi: 10.1038/335188a0
[72]	Zhou Y, Morais-Cabral JH, Kaufman A, et al. (2001) Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution. Nature 414: 43–48.
[73]	Ostermeier C, Iwata S, Ludwig B, et al. (1995) Fv fragment-mediated crystallization of the membrane protein bacterial cytochrome c oxidase. Nat Struct Mol Biol 2: 842–846. doi: 10.1038/nsb1095-842
[74]	Steyaert J, Kobilka BK (2011) Nanobody stabilization of G protein-coupled receptor conformational states. Curr Opin Struc Biol 21: 567–572. doi: 10.1016/j.sbi.2011.06.011
[75]	Domanska K, Vanderhaegen S, Srinivasan V, et al. (2011) Atomic structure of a nanobody-trapped domain-swapped dimer of an amyloidogenic beta2-microglobulin variant. Proc Natl Acad Sci USA 108: 1314–1319. doi: 10.1073/pnas.1008560108
[76]	Korotkov KV, Pardon E, Steyaert J, et al. (2009) Crystal structure of the N-terminal domain of the secretin GspD from ETEC determined with the assistance of a nanobody. Structure 17: 255–265. doi: 10.1016/j.str.2008.11.011
[77]	Loris R, Marianovsky I, Lah J, et al. (2003) Crystal structure of the intrinsically flexible addiction antidote MazE. J Biol Chem 278: 28252–28257. doi: 10.1074/jbc.M302336200
[78]	Wu M, Park YJ, Pardon E, et al. (2011) Structures of a key interaction protein from the Trypanosoma brucei editosome in complex with single domain antibodies. J Struct Biol 174: 124–136. doi: 10.1016/j.jsb.2010.10.007
[79]	De Genst EJ, Guilliams T, Wellens J, et al. (2010) Structure and properties of a complex of alpha-synuclein and a single-domain camelid antibody. J Mol Biol 402: 326–343. doi: 10.1016/j.jmb.2010.07.001
[80]	Rasmussen SG, Choi HJ, Fung JJ, et al. (2011) Structure of a nanobody-stabilized active state of the beta(2) adrenoceptor. Nature 469: 175–180. doi: 10.1038/nature09648
[81]	Manglik A, Kobilka BK, Steyaert J (2017) Nanobodies to study G protein-coupled receptor structure and function. Annu Rev Pharmacol 57: 19–37.
[82]	Ko S, Kim HY, Choi I, et al. (2017) Gold nanoparticles as nucleation-inducing reagents for protein crystallization. Cryst Growth Des 17: 497–503. doi: 10.1021/acs.cgd.6b01346
[83]	Chen YW, Lee CH, Wang YL, et al. (2017) Nanodiamonds as nucleating agents for protein crystallization. Langmuir.
[84]	Nanev CN, Saridakis E, Chayen NE (2017) Protein crystal nucleation in pores. Sci Rep 7: 35821. doi: 10.1038/srep35821
[85]	Abdallah BG, Roy-Chowdhury S, Fromme R, et al. (2016) Protein crystallization in an actuated microfluidic nanowell device. Cryst Growth Des 16: 2074–2082. doi: 10.1021/acs.cgd.5b01748
[86]	Ujwal R, Bowie JU (2011) Crystallizing membrane proteins using lipidic bicelles. Methods 55: 337–341. doi: 10.1016/j.ymeth.2011.09.020
[87]	Agah S, Faham S (2012) Crystallization of membrane proteins in bicelles. Method Mol Biol 914: 3–16.
[88]	Ujwal R, Abramson J (2012) High-throughput crystallization of membrane proteins using the lipidic bicelle method. J Vis Exp: e3383.
[89]	Caffrey M (2015) A comprehensive review of the lipid cubic phase or in meso method for crystallizing membrane and soluble proteins and complexes. Acta Crystallogr F 71: 3–18.
[90]	Yeates TO, Kent SB (2012) Racemic protein crystallography. Annu Rev Biophys 41: 41–61. doi: 10.1146/annurev-biophys-050511-102333
[91]	Wukovitz SW, Yeates TO (1995) Why protein crystals favour some space-groups over others. Nat Struct Mol Biol 2: 1062–1067. doi: 10.1038/nsb1295-1062
[92]	Mandal K, Pentelute BL, Tereshko V, et al. (2009) Racemic crystallography of synthetic protein enantiomers used to determine the X-ray structure of plectasin by direct methods. Protein Sci 18: 1146–1154. doi: 10.1002/pro.127
[93]	Zawadzke LE, Berg JM (1993) The structure of a centrosymmetric protein crystal. Proteins 16: 301–305. doi: 10.1002/prot.340160308
[94]	Dang B, Kubota T, Mandal K, et al. (2013) Native chemical ligation at Asx-Cys, Glx-Cys: chemical synthesis and high-resolution X-ray structure of ShK toxin by racemic protein crystallography. J Am Chem Soc 135: 11911–11919. doi: 10.1021/ja4046795
[95]	Pan M, Gao S, Zheng Y, et al. (2016) Quasi-racemic X-ray structures of K27-linked ubiquitin chains prepared by total chemical synthesis. J Am Chem Soc 138: 7429–7435. doi: 10.1021/jacs.6b04031
[96]	Holcomb J, Spellmon N, Trescott L, et al. (2015) PDZ structure and implication in selective drug design against cystic fibrosis. Curr Drug Targets 16: 945–950. doi: 10.2174/1389450116666141219120125
[97]	Kennedy MB (1995) Origin of PDZ (DHR, GLGF) domains. Trends Biochem Sci 20: 350. doi: 10.1016/S0968-0004(00)89074-X
[98]	Harris BZ, Lim WA (2001) Mechanism and role of PDZ domains in signaling complex assembly. J Cell Sci 114: 3219–3231.
[99]	Lee HJ, Zheng JJ (2010) PDZ domains and their binding partners: structure, specificity, and modification. Cell Commun Signal 8: 8. doi: 10.1186/1478-811X-8-8
[100]	Sheng M, Sala C (2001) PDZ domains and the organization of supramolecular complexes. Annu Rev Neurosci 24: 1–29. doi: 10.1146/annurev.neuro.24.1.1
[101]	Holcomb J, Jiang Y, Guan X, et al. (2014) Crystal structure of the NHERF1 PDZ2 domain in complex with the chemokine receptor CXCR2 reveals probable modes of PDZ2 dimerization. Biochem Bioph Res Co 448: 169–174. doi: 10.1016/j.bbrc.2014.04.085
[102]	Jiang Y, Wang S, Holcomb J, et al. (2014) Crystallographic analysis of NHERF1-PLCbeta3 interaction provides structural basis for CXCR2 signaling in pancreatic cancer. Biochem Bioph Res Co 446: 638–643. doi: 10.1016/j.bbrc.2014.03.028
[103]	Holcomb J, Jiang Y, Lu G, et al. (2014) Structural insights into PDZ-mediated interaction of NHERF2 and LPA(2), a cellular event implicated in CFTR channel regulation. Biochem Bioph Res Co 446: 399–403. doi: 10.1016/j.bbrc.2014.02.128
[104]	Lu G, Wu Y, Jiang Y, et al. (2013) Structural insights into neutrophilic migration revealed by the crystal structure of the chemokine receptor CXCR2 in complex with the first PDZ domain of NHERF1. PLoS One 8: e76219. doi: 10.1371/journal.pone.0076219
[105]	Fouassier L, Yun CC, Fitz JG, et al. (2000) Evidence for ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50) self-association through PDZ-PDZ interactions. J Biol Chem 275: 25039–25045. doi: 10.1074/jbc.C000092200
[106]	Umeda K, Ikenouchi J, Katahira-Tayama S, et al. (2006) ZO-1 and ZO-2 independently determine where claudins are polymerized in tight-junction strand formation. Cell 126: 741–754. doi: 10.1016/j.cell.2006.06.043
[107]	Chang BH, Gujral TS, Karp ES, et al. (2011) A systematic family-wide investigation reveals that ∼30% of mammalian PDZ domains engage in PDZ-PDZ interactions. Chem Biol 18: 1143–1152. doi: 10.1016/j.chembiol.2011.06.013

Reader Comments

Your name:*

Email:*
© 2017 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)