26
|
Merkel S, Weber K, Perrakis A, Göhl J, Hohenberger W. Tumoren des unteren Gastrointestinaltrakts. Chirurg 2010; 81:117-22; 124-26. [DOI: 10.1007/s00104-009-1814-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
27
|
De Marco V, Gillespie PJ, Li A, Karantzelis N, Christodoulou E, Klompmaker R, van Gerwen S, Fish A, Petoukhov MV, Iliou MS, Lygerou Z, Medema RH, Blow JJ, Svergun DI, Taraviras S, Perrakis A. Quaternary structure of the human Cdt1-Geminin complex regulates DNA replication licensing. Proc Natl Acad Sci U S A 2009; 106:19807-12. [PMID: 19906994 PMCID: PMC2775996 DOI: 10.1073/pnas.0905281106] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Indexed: 01/12/2023] Open
Abstract
All organisms need to ensure that no DNA segments are rereplicated in a single cell cycle. Eukaryotes achieve this through a process called origin licensing, which involves tight spatiotemporal control of the assembly of prereplicative complexes (pre-RCs) onto chromatin. Cdt1 is a key component and crucial regulator of pre-RC assembly. In higher eukaryotes, timely inhibition of Cdt1 by Geminin is essential to prevent DNA rereplication. Here, we address the mechanism of DNA licensing inhibition by Geminin, by combining X-ray crystallography, small-angle X-ray scattering, and functional studies in Xenopus and mammalian cells. Our findings show that the Cdt1:Geminin complex can exist in two distinct forms, a "permissive" heterotrimer and an "inhibitory" heterohexamer. Specific Cdt1 residues, buried in the heterohexamer, are important for licensing. We postulate that the transition between the heterotrimer and the heterohexamer represents a molecular switch between licensing-competent and licensing-defective states.
Collapse
|
28
|
Cohen S, Joosten K, Mooij W, Lamzin V, Murshudov G, Perrakis A. Advances in automatic model building and structure completion in the context ofARP/wARP. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308099315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
29
|
Berry IM, Dym O, Esnouf RM, Harlos K, Meged R, Perrakis A, Sussman JL, Walter TS, Wilson J, Messerschmidt A. SPINE high-throughput crystallization, crystal imaging and recognition techniques: current state, performance analysis, new technologies and future aspects. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2006; 62:1137-49. [PMID: 17001091 DOI: 10.1107/s090744490602943x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 07/28/2006] [Indexed: 11/10/2022]
Abstract
This paper reviews the developments in high-throughput and nanolitre-scale protein crystallography technologies within the remit of workpackage 4 of the Structural Proteomics In Europe (SPINE) project since the project's inception in October 2002. By surveying the uptake, use and experience of new technologies by SPINE partners across Europe, a picture emerges of highly successful adoption of novel working methods revolutionizing this area of structural biology. Finally, a forward view is taken of how crystallization methodologies may develop in the future.
Collapse
|
30
|
Aricescu AR, Assenberg R, Bill RM, Busso D, Chang VT, Davis SJ, Dubrovsky A, Gustafsson L, Hedfalk K, Heinemann U, Jones IM, Ksiazek D, Lang C, Maskos K, Messerschmidt A, Macieira S, Peleg Y, Perrakis A, Poterszman A, Schneider G, Sixma TK, Sussman JL, Sutton G, Tarboureich N, Zeev-Ben-Mordehai T, Jones EY. Eukaryotic expression: developments for structural proteomics. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2006; 62:1114-24. [PMID: 17001089 PMCID: PMC7161643 DOI: 10.1107/s0907444906029805] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 07/31/2006] [Indexed: 12/02/2022]
Abstract
The production of sufficient quantities of protein is an essential prelude to a structure determination, but for many viral and human proteins this cannot be achieved using prokaryotic expression systems. Groups in the Structural Proteomics In Europe (SPINE) consortium have developed and implemented high‐throughput (HTP) methodologies for cloning, expression screening and protein production in eukaryotic systems. Studies focused on three systems: yeast (Pichia pastoris and Saccharomyces cerevisiae), baculovirus‐infected insect cells and transient expression in mammalian cells. Suitable vectors for HTP cloning are described and results from their use in expression screening and protein‐production pipelines are reported. Strategies for co‐expression, selenomethionine labelling (in all three eukaryotic systems) and control of glycosylation (for secreted proteins in mammalian cells) are assessed.
Collapse
|
31
|
Alzari PM, Berglund H, Berrow NS, Blagova E, Busso D, Cambillau C, Campanacci V, Christodoulou E, Eiler S, Fogg MJ, Folkers G, Geerlof A, Hart D, Haouz A, Herman MD, Macieira S, Nordlund P, Perrakis A, Quevillon-Cheruel S, Tarandeau F, van Tilbeurgh H, Unger T, Luna-Vargas MPA, Velarde M, Willmanns M, Owens RJ. Implementation of semi-automated cloning and prokaryotic expression screening: the impact of SPINE. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2006; 62:1103-13. [PMID: 17001088 DOI: 10.1107/s0907444906029775] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2005] [Accepted: 07/31/2006] [Indexed: 11/10/2022]
Abstract
The implementation of high-throughput (HTP) cloning and expression screening in Escherichia coli by 14 laboratories in the Structural Proteomics In Europe (SPINE) consortium is described. Cloning efficiencies of greater than 80% have been achieved for the three non-ligation-based cloning techniques used, namely Gateway, ligation-indendent cloning of PCR products (LIC-PCR) and In-Fusion, with LIC-PCR emerging as the most cost-effective. On average, two constructs have been made for each of the approximately 1700 protein targets selected by SPINE for protein production. Overall, HTP expression screening in E. coli has yielded 32% soluble constructs, with at least one for 70% of the targets. In addition to the implementation of HTP cloning and expression screening, the development of two novel technologies is described, namely library-based screening for soluble constructs and parallel small-scale high-density fermentation.
Collapse
|
32
|
Albeck S, Alzari P, Andreini C, Banci L, Berry IM, Bertini I, Cambillau C, Canard B, Carter L, Cohen SX, Diprose JM, Dym O, Esnouf RM, Felder C, Ferron F, Guillemot F, Hamer R, Ben Jelloul M, Laskowski RA, Laurent T, Longhi S, Lopez R, Luchinat C, Malet H, Mochel T, Morris RJ, Moulinier L, Oinn T, Pajon A, Peleg Y, Perrakis A, Poch O, Prilusky J, Rachedi A, Ripp R, Rosato A, Silman I, Stuart DI, Sussman JL, Thierry JC, Thompson JD, Thornton JM, Unger T, Vaughan B, Vranken W, Watson JD, Whamond G, Henrick K. SPINE bioinformatics and data-management aspects of high-throughput structural biology. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2006; 62:1184-95. [PMID: 17001095 PMCID: PMC7161634 DOI: 10.1107/s090744490602991x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 07/31/2006] [Indexed: 05/12/2023]
Abstract
SPINE (Structural Proteomics In Europe) was established in 2002 as an integrated research project to develop new methods and technologies for high‐throughput structural biology. Development areas were broken down into workpackages and this article gives an overview of ongoing activity in the bioinformatics workpackage. Developments cover target selection, target registration, wet and dry laboratory data management and structure annotation as they pertain to high‐throughput studies. Some individual projects and developments are discussed in detail, while those that are covered elsewhere in this issue are treated more briefly. In particular, this overview focuses on the infrastructure of the software that allows the experimentalist to move projects through different areas that are crucial to high‐throughput studies, leading to the collation of large data sets which are managed and eventually archived and/or deposited.
Collapse
|
33
|
Banci L, Bertini I, Cusack S, de Jong RN, Heinemann U, Jones EY, Kozielski F, Maskos K, Messerschmidt A, Owens R, Perrakis A, Poterszman A, Schneider G, Siebold C, Silman I, Sixma T, Stewart-Jones G, Sussman JL, Thierry JC, Moras D. First steps towards effective methods in exploiting high-throughput technologies for the determination of human protein structures of high biomedical value. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2006; 62:1208-17. [PMID: 17001097 DOI: 10.1107/s0907444906029350] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Accepted: 07/28/2006] [Indexed: 11/11/2022]
Abstract
The EC 'Structural Proteomics In Europe' contract is aimed specifically at the atomic resolution structure determination of human protein targets closely linked to health, with a focus on cancer (kinesins, kinases, proteins from the ubiquitin pathway), neurological development and neurodegenerative diseases and immune recognition. Despite the challenging nature of the analysis of such targets, approximately 170 structures have been determined to date. Here, the impact of high-throughput technologies, such as parallel expression of multiple constructs, the use of standardized refolding protocols and optimized crystallization screens or the use of mass spectrometry to assist sample preparation, on the structural biology of mammalian protein targets is illustrated through selected examples.
Collapse
|
34
|
Bahar M, Ballard C, Cohen SX, Cowtan KD, Dodson EJ, Emsley P, Esnouf RM, Keegan R, Lamzin V, Langer G, Levdikov V, Long F, Meier C, Muller A, Murshudov GN, Perrakis A, Siebold C, Stein N, Turkenburg MGW, Vagin AA, Winn M, Winter G, Wilson KS. SPINE workshop on automated X-ray analysis: a progress report. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2006; 62:1170-83. [PMID: 17001094 DOI: 10.1107/s0907444906032197] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 08/14/2006] [Indexed: 11/10/2022]
Abstract
The Structural Proteomics In Europe (SPINE) consortium contained a workpackage to address the automated X-ray analysis of macromolecules. The aim of this workpackage was to increase the throughput of three-dimensional structures while maintaining the high quality of conventional analyses. SPINE was able to bring together developers of software with users from the partner laboratories. Here, the results of a workshop organized by the consortium to evaluate software developed in the member laboratories against a set of bacterial targets are described. The major emphasis was on molecular-replacement suites, where automation was most advanced. Data processing and analysis, use of experimental phases and model construction were also addressed, albeit at a lower level.
Collapse
|
35
|
Evrard GX, Langer GG, Perrakis A, Lamzin VS. Modelling bound ligands with ARP/wARP. Acta Crystallogr A 2006. [DOI: 10.1107/s0108767306095079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
36
|
Venkataraman P, Langer G, Schmitz F, Perrakis A, Lamzin V. Remote services for model building in macromolecular crystallography. Acta Crystallogr A 2006. [DOI: 10.1107/s010876730609739x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
37
|
Buchwald G, van der Stoop P, Weichenrieder O, Perrakis A, van Lohuizen M, Sixma TK. The complex of the polycomb group proteins Ring1B (RNF2) and Bmi1 - a structure-function-analysis. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305089816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
38
|
Perrakis A, Sixma TK, Wilson KS, Lamzin VS. wARP: improvement and extension of crystallographic phases by weighted averaging of multiple-refined dummy atomic models. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2005; 53:448-55. [PMID: 15299911 DOI: 10.1107/s0907444997005696] [Citation(s) in RCA: 379] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
wARP is a procedure that substantially improves crystallographic phases (and subsequently electron-density maps) as an additional step after density-modification methods such as solvent flattening and averaging. The initial phase set is used to create a number of dummy atom models which are subjected to least-squares or maximum-likelihood refinement and iterative model updating in an automated refinement procedure (ARP). Averaging of the phase sets calculated from the refined output models and weighting of structure factors by their similarity to an average vector results in a phase set that improves and extends the initial phases substantially. An important requirement is that the native data have a maximum resolution beyond approximately 2.4 A. The wARP procedure shortens the time-consuming step of model building in crystallographic structure determination and helps to prevent the introduction of errors.
Collapse
|
39
|
Natrajan G, Lamers MH, Winterwerp HHK, Perrakis A, Sixma TK. Structural basis for DNA mismatch recognition by the enzyme MutS. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302095983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
40
|
Xiao B, Spencer J, Clements A, Ali-Khan N, Mittnacht S, Broceno C, Burghammer M, Perrakis A, Marmorstein R, Gamblin SJ. Structure studies on the retinoblastoma tumour suppressor protein and its role in the cell cycle. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302093923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
41
|
Lamzin VS, Perrakis A. The ARP/wARP suite for the automation of crystal structure determination. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302087354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
42
|
Perrakis A, Harkiolaki M, Wilson KS, Lamzin VS. ARP/wARP and molecular replacement. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2001; 57:1445-50. [PMID: 11567158 DOI: 10.1107/s0907444901014007] [Citation(s) in RCA: 405] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2001] [Accepted: 08/21/2001] [Indexed: 11/10/2022]
Abstract
The aim of ARP/wARP is improved automation of model building and refinement in macromolecular crystallography. Once a molecular-replacement solution has been obtained, it is often tedious to refine and rebuild the initial (search) model. ARP/wARP offers three options to automate that task to varying extents: (i) autobuilding of a completely new model based on phases calculated from the molecular-replacement solution, (ii) updating of the initial model by atom addition and deletion to obtain an improved map and (iii) docking of a structure onto a new (or mutated) sequence, followed by rebuilding and refining the side chains in real space. A few examples are presented where ARP/wARP made a considerable difference in the speed of structure solution and/or made possible refinement of otherwise difficult or uninterpretable maps. The resolution range allowing complete autobuilding of protein structures is currently 2.0 A, but for map improvement considerable advances over more conventional refinement techniques are evident even at 3.2 A spacing.
Collapse
|
43
|
Hilge M, Perrakis A, Abrahams JP, Winterhalter K, Piontek K, Gloor SM. Structure elucidation of beta-mannanase: from the electron-density map to the DNA sequence. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2001; 57:37-43. [PMID: 11134925 DOI: 10.1107/s0907444900015547] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 10/27/2000] [Indexed: 11/10/2022]
Abstract
The crystal structure of affinity-purified Thermomonospora fusca beta-mannanase has been solved despite the lack of the major part of the amino-acid sequence. A high-quality electron-density map allowed the identification of a stretch of eight amino acids close to the C-terminus which was used to design a degenerate downstream PCR primer. Together with a specific primer previously derived from the N-terminus, 95.7% of the mannanase gene sequence was obtained from genomic T. fusca DNA by PCR. The structure-derived sequence was then compared with the DNA-derived sequence and corrected when necessary. Applying the presented protocol, there was no need to manually build a model at an early stage of structure determination, an erroneous and tedious process, especially in the absence of the amino-acid sequence. Using the DNA sequence information and the current version of ARP/wARP, 281 residues, or 93% of the polypeptide chain (including side chains), were built and refined to an R factor of 16.5% without any manual intervention.
Collapse
|
44
|
Lamzin VS, Perrakis A, Bricogne G, Jiang J, Swaminathan S, Sussman JL. Apotheosis, not apocalypse: methods in protein crystallography. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2000; 56:1510-1. [PMID: 11053868 DOI: 10.1107/s0907444900010751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2000] [Accepted: 07/31/2000] [Indexed: 11/10/2022]
|
45
|
Lamzin VS, Perrakis A. Current state of automated crystallographic data analysis. NATURE STRUCTURAL BIOLOGY 2000; 7 Suppl:978-81. [PMID: 11104005 DOI: 10.1038/80763] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A goal of structural biology--and of structural genomics in particular--is to improve the underlying methodology for high-throughput determination of three-dimensional structures of biological macromolecules. Here we address issues related to the development, automation and streamlining of the process of macromolecular X-ray crystal structure solution.
Collapse
|
46
|
Lamers MH, Perrakis A, Enzlin JH, Winterwerp HH, de Wind N, Sixma TK. The crystal structure of DNA mismatch repair protein MutS binding to a G x T mismatch. Nature 2000; 407:711-7. [PMID: 11048711 DOI: 10.1038/35037523] [Citation(s) in RCA: 499] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
DNA mismatch repair ensures genomic integrity on DNA replication. Recognition of a DNA mismatch by a dimeric MutS protein initiates a cascade of reactions and results in repair of the newly synthesized strand; however, details of the molecular mechanism remain controversial. Here we present the crystal structure at 2.2 A of MutS from Escherichia coli bound to a G x T mismatch. The two MutS monomers have different conformations and form a heterodimer at the structural level. Only one monomer recognizes the mismatch specifically and has ADP bound. Mismatch recognition occurs by extensive minor groove interactions causing unusual base pairing and kinking of the DNA. Nonspecific major groove DNA-binding domains from both monomers embrace the DNA in a clamp-like structure. The interleaved nucleotide-binding sites are located far from the DNA. Mutations in human MutS alpha (MSH2/MSH6) that lead to hereditary predisposition for cancer, such as hereditary non-polyposis colorectal cancer, can be mapped to this crystal structure.
Collapse
|
47
|
Lamers M, Perrakis A, Enzlin J, Winterwerp H, de Wind N, Sixma T. Crystal structure of the E. coliDNA mismatch repair protein MutS in complex with a GT mismatch. Acta Crystallogr A 2000. [DOI: 10.1107/s0108767300022546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
48
|
Perrakis A, Morris R, Lamzin V. ARP/wARP: Procedures for automated model building and refinement. Acta Crystallogr A 2000. [DOI: 10.1107/s010876730002153x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
|
49
|
Bracher A, Perrakis A, Dresbach T, Betz H, Weissenhorn W. Crystal structure of neuronal Sec1 from the squid Loligo pealei. Acta Crystallogr A 2000. [DOI: 10.1107/s0108767300026192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
50
|
Bracher A, Perrakis A, Dresbach T, Betz H, Weissenhorn W. The X-ray crystal structure of neuronal Sec1 from squid sheds new light on the role of this protein in exocytosis. Structure 2000; 8:685-94. [PMID: 10903948 DOI: 10.1016/s0969-2126(00)00156-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Sec1-like molecules have been implicated in a variety of eukaryotic vesicle transport processes including neurotransmitter release by exocytosis. They regulate vesicle transport by binding to a t-SNARE from the syntaxin family. This process is thought to prevent SNARE complex formation, a protein complex required for membrane fusion. Whereas Sec1 molecules are essential for neurotransmitter release and other secretory events, their interaction with syntaxin molecules seems to represent a negative regulatory step in secretion. RESULTS Here we report the X-ray crystal structure of a neuronal Sec1 homologue from squid, s-Sec1, at 2.4 A resolution. Neuronal s-Sec1 is a modular protein that folds into a V-shaped three-domain assembly. Peptide and mutagenesis studies are discussed with respect to the mechanism of Sec1 regulation. Comparison of the structure of squid s-Sec1 with the previously determined structure of rat neuronal Sec1 (n-Sec1) bound to syntaxin-1a indicates conformational rearrangements in domain III induced by syntaxin binding. CONCLUSIONS The crystal structure of s-Sec1 provides the molecular scaffold for a number of molecular interactions that have been reported to affect Sec1 function. The structural differences observed between s-Sec1 and the structure of a rat n-Sec1-syntaxin-1a complex suggest that local conformational changes are sufficient to release syntaxin-1a from neuronal Sec1, an active process that is thought to involve additional effector molecule(s).
Collapse
|