The major light-harvesting complex of photosystem II (LHC-II) serves as the principal solar energy collector in the photosynthesis of green plants and presumably also functions in photoprotection under high-light conditions. Here we report the first X-ray structure of LHC-II in icosahedral proteoliposome assembly at atomic detail. One asymmetric unit of a large R32 unit cell contains ten LHC-II monomers. The 14 chlorophylls (Chl) in each monomer can be unambiguously distinguished as eight Chla and six Chlb molecules. Assignment of the orientation of the transition dipole moment of each chlorophyll has been achieved. All Chlb are located around the interface between adjacent monomers, and together with Chla they are the basis for efficient light harvesting. Four carotenoid-binding sites per monomer have been observed. The xanthophyll-cycle carotenoid at the monomer-monomer interface may be involved in the non-radiative dissipation of excessive energy, one of the photoprotective strategies that have evolved in plants.

CP29, one of the minor light-harvesting complexes of higher-plant photosystem II, absorbs and transfers solar energy for photosynthesis and also has important roles in photoprotection. We have solved the crystal structure of spinach CP29 at 2.80-Å resolution. Each CP29 monomer contains 13 chlorophyll and 3 carotenoid molecules, which differs considerably from the major light-harvesting complex LHCII and the previously proposed CP29 model. The 13 chlorophyll-binding sites are assigned as eight chlorophyll a sites, four chlorophyll b and one putative mixed site occupied by both chlorophylls a and b. Based on the present X-ray structure, an integrated pigment network in CP29 is constructed. Two special clusters of pigment molecules, namely a615-a611-a612-Lut and Vio(Zea)-a603-a609, have been identified and might function as potential energy-quenching centers and as the exit or entrance in energy-transfer pathways.

The photosystem II protein PsbS has an essential role in qE-type nonphotochemical quenching, which protects plants from photodamage under excess light conditions. qE is initiated by activation of PsbS by low pH, but the mechanism of PsbS action remains elusive. Here we report the low-pH crystal structures of PsbS from spinach in its free form and in complex with the qE inhibitor N,N'-dicyclohexylcarbodiimide (DCCD), revealing that PsbS adopts a unique folding pattern, and, unlike other members of the light-harvesting-complex superfamily, it is a noncanonical pigment-binding protein. Structural and biochemical evidence shows that both active and inactive PsbS form homodimers in the thylakoid membranes, and DCCD binding disrupts the lumenal intermolecular hydrogen bonds of the active PsbS dimer. Activation of PsbS by low pH during qE may involve a conformational change associated with altered lumenal intermolecular interactions of the PsbS dimer.

The three-dimensional structures of brain pyridoxal kinase and its complex with the nucleotide ATP have been elucidated in the dimeric form at 2.1 and 2.6 Å, respectively. Results have shown that pyridoxal kinase, as an enzyme obeying random sequential kinetics in catalysis, does not possess a lid shape structure common to all kinases in the ribokinase superfamily. This finding has been shown to be in line with the condition that pyridoxal kinase binds substrates with variable sizes of chemical groups at position 4 of vitamin B 6 and its derivatives. In addition, the enzyme contains a 12-residue peptide loop in the active site for the prevention of premature hydrolysis of ATP. Conserved amino acid residues Asp 118 and Tyr 127 in the peptide loop could be moved to a position covering the nucleotide after its binding so that its chance to hydrolyze in the aqueous environment of the active site was reduced. With respect to the evolutionary trend of kinase enzymes, the existence of this loop in pyridoxal kinase could be classified as an independent category in the ribokinase superfamily according to the structural feature found and mechanism followed in catalysis.

BackgroundAlthough a few studies have been reported on predictive factors of postoperative diabetes remission, the conclusions remain inconsistent. This meta-analysis aimed to assess the preoperative clinical factors for type 2 diabetes mellitus (T2DM) remission after bariatric surgery.MethodsThe Cochrane Library, PubMed, MEDLINE, Embase, and CINAHL databases were searched. All human studies published in English between 1 January 1992 and 1 September 2013 reporting on the parameters of interest were included.ResultsIn total, 15 studies involving 1,753 bariatric surgery patients were selected. Analyses were performed separately for the parameters of interest. T2DM remission was observed to be negatively correlated with age, diabetes duration, insulin use, and HbA1c levels. Baseline body mass index (BMI) and C-peptide levels were positively associated with the remission rate in Asian patients. However, there was no significant association between gender and remission rate.ConclusionsPatients with younger age, short diabetes duration, better glucose control, and better β cell function were more likely to achieve T2DM remission after bariatric surgery. However, further randomized controlled trials with uniform remission criteria should be conducted to provide more reliable evidence.

Fibroblast activation protein-alpha (FAPα) is a cell surface glycoprotein which is selectively expressed by tumor-associated fibroblasts in malignant tumors but rarely on normal tissues. FAPα has also been reported to promote tumor growth and invasion and therefore has been of increasing interest as a promising target for designing tumor-targeted drugs and imaging agents. Although medicinal study on FAPα inhibitors has led to the discovery of many FAPα-targeting inhibitors including a drug candidate in a phase II clinical trial, the development of imaging probes to monitor the expression and activity of FAPα in vivo has largely lagged behind. Herein we report an activatable near infrared (NIR) fluorescent probe (ANPFAP) for in vivo optical imaging of FAPα. The ANPFAP consists of a NIR dye (Cy5.5) and a quencher dye (QSY21) which are linked together by a short peptide sequence (KGPGPNQC) specific for FAPα cleavage. Because of the efficient fluorescence resonance energy transfer (FRET) between Cy5.5 and QSY21 in ANPFAP, high contrast on the NIR fluorescence signal can be achieved after the cleavage of the peptide sequence by FAPα both in vitro and in vivo. In vitro assay on ANPFAP indicated the specificity of the probe to FAPα. The in vivo optical imaging using ANPFAP showed fast tumor uptake as well as high tumor to background contrast on U87MG tumor models with FAPα expression, while much lower signal and tumor contrast were observed in the C6 tumor without FAPα expression, demonstrating the in vivo targeting specificity of the ANPFAP. Ex vivo imaging also demonstrated ANPFAP had high tumor uptake at 4 h post injection. Collectively, these results indicated that ANPFAP could serve as a useful NIR optical probe for early detection of FAPα expressing tumors.

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BackgroundAcupuncture therapy for preventive and treatment of postoperative nausea and vomiting(PONV), a condition which commonly present after anaesthesia and surgery is a subject of growing interest. ObjectiveThis paper included a systematic review and meta-analysis on the effect of different type of acupuncture and acupoint selection in PONV prevention and treatment. MethodsRandomised controlled trials(RCTs) comparing acupuncture with non-acupuncture treatment were identified from databases PubMed, Cochrane, EBSCO, Ovid, CNKI and Wanfangdata. Meta-analysis on eligible studies was performed using fixed-effects model with RevMan 5.2. Results were expressed as RR for dichotomous data, with 95%CI. ResultsThirty RCTs, 1276 patients (intervention) and 1258 patients (control) were identified. Meta-analysis showed that PC6 acupuncture significantly reduced the number of cases of early vomiting (postoperative 0-6h) (RR=0.36, 95%CI 0.19,0.71; P=0.003) and nausea (postoperative 0-24h) (RR=0.25, 95%CI 0.10,0.61; P=0.002), but not early nausea (postoperative 0-6h) (RR=0.64, 95%CI 0.34,1.19; P=0.150) and vomiting (postoperative 0-24h) (RR=0.82, 95%CI 0.48,1.38; P=0.450). PC6 acupressure significantly reduced the number of cases of nausea (RR=0.71, 95%CI 0.57,0.87; P=0.001) and vomiting (RR=0.62, 95%CI 0.49,0.80; P=0.000) at postoperative 0-24h. PC6 electro-acupoint stimulation significantly reduced the number of cases of nausea (RR=0.49, 95%CI 0.38,0.63; P<0.000) and vomiting (RR=0.50, 95%CI 0.36,0.70; P<0.000) at postoperative 0-24h. Stimulation of PC6 with other acupoint(s) significantly reduced the number of cases of nausea and vomiting (RR=0.29, 95%CI 0.17,0.49; P<0.000) at postoperative 0-24h. Stimulation of other acupoint(s)(non PC6) also significantly reduced the number of cases of nausea and vomiting (RR=0.63, 95%CI 0.49,0.81; P=0.000) at postoperative 0-24h. However, the quality of study was generally low in studies of PC6 combined with other acupoint(s) and other acupoint(s). Details of blinding were not reported in most reports. ConclusionsBesides PC6, PC6 combined with other acupoint(s) and other alternative acupoint(s) might be beneficial in prevention and treatment of PONV, the evidence justifies future high-quality studies.