Identification and functional analysis of thylakoid membrane proteome

Membrane proteins play crucial roles in many biological functions. Identities and functions of most membrane proteins remain to be revealed. New technological breakthroughs in proteomics together with the availability of genomic sequence information make it possible to study functions of membrane proteins on a genome-wide scale. We used a multidisciplinary approach combining biochemistry, genetics, proteomics and bioinformatics to study the functions of the thylakoid proteome of Synechocystis sp. PCC6803. The thylakoid membrane proteins were separated into peripheral and integral fractions and resolved into 2-D gels with different pH ranges. The protein spots in the 2-D gels were subjected to peptide mass fingerprinting analysis, and totally 390 out of 558 analyzed spots were identified as protein products of 128 individual genes, of which 38 gene encode hypothetical proteins with unknown function. To study the function of some hypothetical proteins, we inactivated a set of genes, and 10 knockout mutants were obtained. The growth analysis for the mutant cells revealed that only one mutant (H1) which has a deletion in the ORF slr0110, showed conditional growth phenotype. Detailed analysis indicated that the H1 mutant is sensitive to both glucose and light, which is caused by the over-reduction of the PQ pool in the thylakoid membrane. The ID and the structural and functional information of the identified proteins as well as the 2-D reference maps were included in a web-based relational database for thylakoid membrane proteins. The database was constructed with MySQL, and the application programs were developed with SQL, PERL, JAVASCRIPT and HTML. Users can search the information of identified proteins and compare their own identified proteins with the identified proteins in the database. A manager interface is also provided for the routine maintenance of the database

2-(Eth­oxy­carbon­yl)pyridinium nitrate

In the title compound, C8H10NO2 +·NO3 −, the cation is essentially planar with C—O—C—C and C—O—C—O torsion angles of −178.1 (2) and 2.1 (4)°, respectively. In the crystal, N—H⋯O and C—H⋯O hydrogen-bond inter­actions stabilize the structure

SCFSAP controls organ size by targeting PPD proteins for degradation in Arabidopsis thaliana

Control of organ size by cell proliferation and growth is a fundamental process, but the mechanisms that determine the final size of organs are largely elusive in plants. We have previously revealed that the ubiquitin receptor DA1 regulates organ size by repressing cell proliferation in Arabidopsis. Here we report that a mutant allele of STERILE APETALA (SAP) suppresses the da1-1 mutant phenotype. We show that SAP is an F-box protein that forms part of a SKP1/Cullin/F-box E3 ubiquitin ligase complex and controls organ size by promoting the proliferation of meristemoid cells. Genetic analyses suggest that SAP may act in the same pathway with PEAPOD1 and PEAPOD2, which are negative regulators of meristemoid proliferation, to control organ size, but does so independently of DA1. Further results reveal that SAP physically associates with PEAPOD1 and PEAPOD2, and targets them for degradation. These findings define a molecular mechanism by which SAP and PEAPOD control organ size

4-[(1-Adamant­yl)carbamo­yl]pyridinium chloride

In the title compound, C16H21N2O+·Cl−, the amide group makes a dihedral angle of 25.9 (1)° with respect to the pyridine ring. In the crystal, inter­molecular N—H⋯Cl bonds and weak C—H⋯Cl and C—H⋯O contacts link the cations and the anions into layers parallel to the ac plane. The layers are packed along [010] by hydro­phobic inter­actions between adamantane units

4-Carb­oxy­pyridinium bromide

In the title compound, C6H6NO2 +·Br−, the hy­droxy and carbonyl groups make torsion angles of 164.8 (4) and −17.6 (6)°, respectively, with the pyridinium ring. Inter­molecular N—H⋯Br, O—H⋯Br and C—H⋯O hydrogen bonds contribute to the stability of the structure and link the mol­ecules into chains along the b axis

Design, simulation and experiment of particle dampers attached to a precision instrument in spacecraft

Aiming at attenuating the vibration of a precision instrument in spacecraft, multiple particle dampers are designed and their damping performances are evaluated. Firstly, the vibrating table test for the primary system under sin-swept excitation is conducted to acquire the vibration characteristic. Then enclosures attached to the installing bracket are designed and fabricated elaborately. Using discrete element-finite element (DE-FE) coupling algorithm, the effects of some system parameters (such as: mass ratio, particle material, numbers of dampers and cavity depth) are investigated to optimize the damping capacity of particle dampers. Furthermore, a series of experiments are conducted to verify the performance of particle dampers under dynamic load. The results indicate that the transfer functions of acceleration in Y and Z direction decrease at 22.58 % and 77.38 % respectively, while only 3.1 % mass of the primary system is attached

Nonlinear behavior evolution and squeal analysis of disc brake based on different friction models

A four-degree-of-freedom model of disc brake with friction and contact loss nonlinearities is developed to investigate the mechanism and dynamic characteristics of brake squeal. The nonlinear equations of motion are presented, and Coulomb and Stribeck friction models are applied and compared in the analysis. The effects of key parameters on system stability are investigated based on the linear equations around the equilibrium point using the complex eigenvalue analysis method. Mode-coupling motion is found to be one significant mechanism to initiate the system instability and lead to brake squeal, and is exceptionally reliant on the parameter configurations of brake system. Numerical solutions of the nonlinear equations of motion are obtained to examine the dynamic behaviors and find the routes to squeal of the brake system with nonlinearities. Results demonstrate that the tangential stiffness of the pad and the rotating velocity of the disc play important roles on the occurrence of stick-slip vibration resulting from the falling characteristic of friction coefficient, and contact loss nonlinearity may make system become unstable even for constant friction coefficient. The separation between the brake pad and disc is dependent on the ratio of normal stiffness of pad/disc and contact stiffness. Strong nonlinear items of the brake system may lead to complicated quasi-periodic and chaotic motions, resulting in squeal problem