A novel type of microglomerular synaptic complex in the polarization vision pathway of the locust brain

2007 ◽  
Vol 506 (2) ◽  
pp. 288-300 ◽  
Author(s):  
Ulrike Träger ◽  
Robert Wagner ◽  
Bernhard Bausenwein ◽  
Uwe Homberg
Keyword(s):  
Polarization Vision ◽  
Synaptic Complex

scholarly journals Site-Directed Mutagenesis Studies of Tn5 Transposase Residues Involved in Synaptic Complex Formation

2007 ◽  
Vol 189 (20) ◽  
pp. 7436-7441 ◽  
Author(s):  
Soheila Vaezeslami ◽  
Rachel Sterling ◽  
William S. Reznikoff
Keyword(s):  
Complex Formation ◽  
Catalytic Reactions ◽  
Site Directed Mutagenesis ◽  
Dna Interactions ◽  
Synaptic Complex ◽  
Biochemical Assays ◽  
Protein Dna Interactions ◽  
End Sequences ◽  
Tn5 Transposase ◽  
Cocrystal Structure

ABSTRACT Transposition (the movement of discrete segments of DNA, resulting in rearrangement of genomic DNA) initiates when transposase forms a dimeric DNA-protein synaptic complex with transposon DNA end sequences. The synaptic complex is a prerequisite for catalytic reactions that occur during the transposition process. The transposase-DNA interactions involved in the synaptic complex have been of great interest. Here we undertook a study to verify the protein-DNA interactions that lead to synapsis in the Tn5 system. Specifically, we studied (i) Arg342, Glu344, and Asn348 and (ii) Ser438, Lys439, and Ser445, which, based on the previously published cocrystal structure of Tn5 transposase bound to a precleaved transposon end sequence, make cis and trans contacts with transposon end sequence DNA, respectively. By using genetic and biochemical assays, we showed that in all cases except one, each of these residues plays an important role in synaptic complex formation, as predicted by the cocrystal structure.

scholarly journals Real-time analysis of RAG complex activity in V(D)J recombination

2016 ◽  
Vol 113 (42) ◽  
pp. 11853-11858 ◽  
Author(s):  
Jennifer Zagelbaum ◽  
Noriko Shimazaki ◽  
Zitadel Anne Esguerra ◽  
Go Watanabe ◽  
Michael R. Lieber ◽  
...  
Keyword(s):  
Real Time ◽  
Single Molecule ◽  
Conformational Changes ◽  
Signal Sequence ◽  
High Mobility ◽  
Time Analysis ◽  
Complex Activity ◽  
Synaptic Complex ◽  
Single Molecule Fret ◽  
Real Time Analysis

Single-molecule FRET (smFRET) and single-molecule colocalization (smCL) assays have allowed us to observe the recombination-activating gene (RAG) complex reaction mechanism in real time. Our smFRET data have revealed distinct bending modes at recombination signal sequence (RSS)-conserved regions before nicking and synapsis. We show that high mobility group box 1 (HMGB1) acts as a cofactor in stabilizing conformational changes at the 12RSS heptamer and increasing RAG1/2 binding affinity for 23RSS. Using smCL analysis, we have quantitatively measured RAG1/2 dwell time on 12RSS, 23RSS, and non-RSS DNA, confirming a strict RSS molecular specificity that was enhanced in the presence of a partner RSS in solution. Our studies also provide single-molecule determination of rate constants that were previously only possible by indirect methods, allowing us to conclude that RAG binding, bending, and synapsis precede catalysis. Our real-time analysis offers insight into the requirements for RSS–RSS pairing, architecture of the synaptic complex, and dynamics of the paired RSS substrates. We show that the synaptic complex is extremely stable and that heptamer regions of the 12RSS and 23RSS substrates in the synaptic complex are closely associated in a stable conformational state, whereas nonamer regions are perpendicular. Our data provide an enhanced and comprehensive mechanistic description of the structural dynamics and associated enzyme kinetics of variable, diversity, and joining [V(D)J] recombination.

scholarly journals Ultraviolet polarization vision in fishes: possible mechanisms for coding e–vector

2000 ◽  
Vol 355 (1401) ◽  
pp. 1187-1190 ◽  
Author(s):  
Craig W. Hawryshyn
Keyword(s):  
Polarized Light ◽  
Spatial Arrangement ◽  
Short Review ◽  
Research Problem ◽  
Polarization Sensitivity ◽  
Polarization Vision ◽  
Selective Reflection ◽  
Mosaic Pattern ◽  
Cone Mosaic ◽  
Biophysical Mechanism

Polarization vision in vertebrates has been marked with significant controversy over recent decades. In the last decade, however, models from two laboratories have indicated that the spatial arrangement of photoreceptors provides the basis for polarization sensitivity.Work in my laboratory, in collaboration with I. Novales Flamarique and F. I. Harosi, has shown that polarization sensitivity depends on a well–defined square cone mosaic pattern and that the biophysical properties of the square cone mosaic probably account for polarization vision in the ultraviolet spectrum. The biophysical mechanism appears to be based on the selective reflection of axial–polarized light by the partitioning membrane, formed along the contact zone between the members of the double cones, onto neighbouring ultraviolet–sensitive cones. In this short review, I discuss the historical development of this research problem.

scholarly journals Architecture of the Hin Synaptic Complex during Recombination

Cell ◽  
2004 ◽  
Vol 119 (1) ◽  
pp. 33-45 ◽  
Author(s):  
Gautam Dhar ◽  
Erin R. Sanders ◽  
Reid C. Johnson
Keyword(s):  
Synaptic Complex

scholarly journals RAG-Heptamer Interaction in the Synaptic Complex Is a Crucial Biochemical Checkpoint for the 12/23 Recombination Rule

2007 ◽  
Vol 283 (8) ◽  
pp. 4877-4885 ◽  
Author(s):  
Tadashi Nishihara ◽  
Fumikiyo Nagawa ◽  
Takeshi Imai ◽  
Hitoshi Sakano
Keyword(s):  
Synaptic Complex

Structure of a NHEJ Polymerase-Mediated DNA Synaptic Complex

Science ◽  
2007 ◽  
Vol 318 (5849) ◽  
pp. 456-459 ◽  
Author(s):  
N. C. Brissett ◽  
R. S. Pitcher ◽  
R. Juarez ◽  
A. J. Picher ◽  
A. J. Green ◽  
...  
Keyword(s):  
Synaptic Complex

scholarly journals Visual Behavior Based Bio-Inspired Polarization Techniques in Computer Vision and Robotics

2012 ◽  
pp. 243-272 ◽  
Author(s):  
Abd El Rahman Shabayek ◽  
Olivier Morel ◽  
David Fofi
Keyword(s):  
Computer Vision ◽  
Object Recognition ◽  
Visual Perception ◽  
Polarization Vision ◽  
Visual Behavior ◽  
Biologically Inspired ◽  
Long Time ◽  
Comprehensive Survey ◽  
High Level ◽  
And Robotics

For long time, it was thought that the sensing of polarization by animals is invariably related to their behavior, such as navigation and orientation. Recently, it was found that polarization can be part of a high-level visual perception, permitting a wide area of vision applications. Polarization vision can be used for most tasks of color vision including object recognition, contrast enhancement, camouflage breaking, and signal detection and discrimination. The polarization based visual behavior found in the animal kingdom is briefly covered. Then, the authors go in depth with the bio-inspired applications based on polarization in computer vision and robotics. The aim is to have a comprehensive survey highlighting the key principles of polarization based techniques and how they are biologically inspired.

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