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1.
Plant Cell ; 33(3): 603-622, 2021 05 05.
Article in English | MEDLINE | ID: mdl-33955492

ABSTRACT

In wheat (Triticum aestivum L.), breeding efforts have focused intensively on improving grain yield and quality. For quality, the content and composition of seed storage proteins (SSPs) determine the elasticity of wheat dough and flour processing quality. Moreover, starch levels in seeds are associated with yield. However, little is known about the mechanisms that coordinate SSP and starch accumulation in wheat. In this study, we explored the role of the endosperm-specific NAC transcription factor TaNAC019 in coordinating SSP and starch accumulation. TaNAC019 binds to the promoters of TaGlu-1 loci, encoding high molecular weight glutenin (HMW-GS), and of starch metabolism genes. Triple knock-out mutants of all three TaNAC019 homoeologs exhibited reduced transcript levels for all SSP types and genes involved in starch metabolism, leading to lower gluten and starch contents, and in flour processing quality parameters. TaNAC019 directly activated the expression of HMW-GS genes by binding to a specific motif in their promoters and interacting with the TaGlu-1 regulator TaGAMyb. TaNAC019 also indirectly regulated the expression of TaSPA, an ortholog of maize Opaque2 that activates SSP accumulation. Therefore, TaNAC019 regulation of starch- and SSP-related genes has key roles in wheat grain quality. Finally, we identified an elite allele (TaNAC019-BI) associated with flour processing quality, providing a candidate gene for breeding wheat with improved quality.


Subject(s)
Endosperm/metabolism , Plant Proteins/metabolism , Starch/metabolism , Transcription Factors/metabolism , Alleles , Endosperm/genetics , Glutens/genetics , Glutens/metabolism , Plant Proteins/genetics , Starch/genetics , Transcription Factors/genetics , Triticum/genetics , Triticum/metabolism
2.
Int J Mol Sci ; 24(13)2023 Jul 04.
Article in English | MEDLINE | ID: mdl-37446250

ABSTRACT

The quality of wheat primarily depends on its storage protein quality, especially in regards to gluten content and high-molecular-weight glutenin subunits (HMW-GS). The number of HMW-GS alleles is limited in bread wheat (Triticum aestivum L.), whereas it is abundant in wheat relatives. Therefore, HMW-GS alleles from wheat relatives could provide a potential for improving quality in wheat breeding. Thinopyrum elongatum (EE) is one of the relatives of wheat. The E genome is closely related to the ABD genome in wheat; therefore, Th. elongatum is often used as an excellent exogenous gene donor for wheat genetic improvement. In this study, the high-molecular glutenin subunit gene was cloned and sequenced from Th. elongatum. A specific molecular marker for identifying the Glu-1Ey subunit gene was developed and applied to detected wheat-Th. elongatum alien introgression lines. Quality analysis indicated that the substitution and addition lines containing Th. elongatum alleles significantly (p < 0.05) increased grain protein content by 3.76% to 5.11%, wet-gluten content by 6.55% to 8.73%, flour 8-MW by 0.25% to 6.35%, and bread volume value by 33.77 mL to 246.50 mL, in comparing it with Chinese Spring. The GMP content and lactic acid SRC showed significant positive correlations with flour processing quality and might be used as indicators for wheat quality. The results were expected to provide a novel route for improving processing quality in wheat quality breeding.


Subject(s)
Plant Breeding , Triticum , Triticum/genetics , Triticum/metabolism , Poaceae/genetics , Glutens/genetics , Glutens/metabolism , Molecular Weight , Protein Subunits/metabolism
3.
Plant Physiol ; 186(4): 1951-1969, 2021 08 03.
Article in English | MEDLINE | ID: mdl-33890670

ABSTRACT

Polyploidy occurs prevalently and plays an important role during plant speciation and evolution. This phenomenon suggests polyploidy could develop novel features that enable them to adapt wider range of environmental conditions compared with diploid progenitors. Bread wheat (Triticum aestivum L., BBAADD) is a typical allohexaploid species and generally exhibits greater salt tolerance than its tetraploid wheat progenitor (BBAA). However, little is known about the underlying molecular basis and the regulatory pathway of this trait. Here, we show that the histone acetyltransferase TaHAG1 acts as a crucial regulator to strengthen salt tolerance of hexaploid wheat. Salinity-induced TaHAG1 expression was associated with tolerance variation in polyploidy wheat. Overexpression, silencing, and CRISPR-mediated knockout of TaHAG1 validated the role of TaHAG1 in salinity tolerance of wheat. TaHAG1 contributed to salt tolerance by modulating reactive oxygen species (ROS) production and signal specificity. Moreover, TaHAG1 directly targeted a subset of genes that are responsible for hydrogen peroxide production, and enrichment of TaHAG1 triggered increased H3 acetylation and transcriptional upregulation of these loci under salt stress. In addition, we found the salinity-induced TaHAG1-mediated ROS production pathway is involved in salt tolerance difference of wheat accessions with varying ploidy. Our findings provide insight into the molecular mechanism of how an epigenetic regulatory factor facilitates adaptability of polyploidy wheat and highlights this epigenetic modulator as a strategy for salt tolerance breeding in bread wheat.


Subject(s)
Histone Acetyltransferases/genetics , Plant Proteins/genetics , Polyploidy , Salt Tolerance/genetics , Triticum/physiology , Histone Acetyltransferases/metabolism , Plant Breeding , Plant Proteins/metabolism , Triticum/enzymology , Triticum/genetics
4.
Biomacromolecules ; 23(1): 182-195, 2022 01 10.
Article in English | MEDLINE | ID: mdl-34889593

ABSTRACT

Electronic skin has aroused extensive research interest due to high similarity with human skin. Realizing a multifunctional electronic skin that is highly consistent with skin functions and endowed with more other functions is now a more urgent need and important challenge. Here, we use 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized cellulose nanofibril (TOCN) dispersion and highly conductive Ti3C2TX dispersion to prepare TOCN/Ti3C2TX composite film through vacuum-assisted filtration. The obtained composite film imitating the nacre-like lamellar structure of natural shells has good mechanical properties (124.6 MPa of tensile strength). Meanwhile, the composite film also showed excellent electromagnetic shielding performance (36 dB), biocompatibility, and antibacterial properties. In addition, the piezoresistive sensor assembled from the composite film exhibited a high sensitivity (11.6 kPa-1), fast response and recovery time (≤10 ms), ultralow monitoring limit (0.2 Pa), and long-term stability (>10 000 cycles). It also could detect human daily activities such as finger bent, chewing, and so on.


Subject(s)
Cellulose, Oxidized , Wearable Electronic Devices , Anti-Bacterial Agents/pharmacology , Electromagnetic Phenomena , Humans , Tensile Strength
5.
Int J Mol Sci ; 23(7)2022 Mar 25.
Article in English | MEDLINE | ID: mdl-35408932

ABSTRACT

Mitogen-activated protein kinase (MAPK) cascades play crucial roles in almost all biological processes in plants. They transduce extracellular cues into cells, typically through linear and sequential phosphorylation and activation of members of the signaling cascades. However, accumulating data suggest various regulatory mechanisms of plant MAPK cascades in addition to the traditional phosphorylation pathway, in concert with their large numbers and coordinated roles in plant responses to complex ectocytic signals. Here, we highlight recent studies that describe the uncanonical mechanism of regulation of MAPK cascades, regarding the activation of each tier of the signaling cascades. More particularly, we discuss the unusual role for MAPK kinase kinases (MAPKKKs) in the regulation of MAPK cascades, as accumulating data suggest the non-MAPKKK function of many MAPKKKs. In addition, future work on the biochemical activation of MAPK members that needs attention will be discussed.


Subject(s)
MAP Kinase Signaling System , Mitogen-Activated Protein Kinases , MAP Kinase Kinase Kinases/metabolism , Mitogen-Activated Protein Kinases/metabolism , Phosphorylation , Plants/metabolism
6.
Plant Physiol ; 181(1): 179-194, 2019 09.
Article in English | MEDLINE | ID: mdl-31209125

ABSTRACT

In grass crops, leaf angle is determined by development of the lamina joint, the tissue connecting the leaf blade and sheath, and is closely related to crop architecture and yield. In this study, we identified a mutant generated by fast neutron radiation that exhibited an erect leaf phenotype caused by defects in lamina joint development. Map-based cloning revealed that the gene TaSPL8, encoding a SQUAMOSA PROMOTER BINDING-LIKE (SPL) protein, is deleted in this mutant. TaSPL8 knock-out mutants exhibit erect leaves due to loss of the lamina joint, compact architecture, and increased spike number especially in high planting density, suggesting similarity with its LIGULESS1 homologs in maize (Zea mays) and rice (Oryza sativa). Hence, LG1 could be a robust target for plant architecture improvement in grass species. Common wheat (Triticum aestivum, 2n = 6× = 42; BBAADD) is an allohexaploid containing A, B, and D subgenomes and the homeologous gene of TaSPL8 from the D subgenome contributes to the length of the lamina joint to a greater extent than that from the A and B subgenomes. Comparison of the transcriptome between the Taspl8 mutant and the wild type revealed that TaSPL8 is involved in the activation of genes related to auxin and brassinosteroid pathways and cell elongation. TaSPL8 binds to the promoters of the AUXIN RESPONSE FACTOR gene and of the brassinosteroid biogenesis gene CYP90D2 and activates their expression. These results indicate that TaSPL8 might regulate lamina joint development through auxin signaling and the brassinosteroid biosynthesis pathway.


Subject(s)
Brassinosteroids/metabolism , Indoleacetic Acids/metabolism , Plant Growth Regulators/metabolism , Plant Proteins/metabolism , Transcriptome , Triticum/genetics , Gene Expression Regulation, Plant , Phenotype , Plant Leaves/genetics , Plant Leaves/growth & development , Plant Leaves/physiology , Plant Proteins/genetics , Promoter Regions, Genetic/genetics , Signal Transduction , Triticum/growth & development , Triticum/physiology
7.
New Phytol ; 239(1): 5-6, 2023 07.
Article in English | MEDLINE | ID: mdl-37182221

Subject(s)
Triticum
8.
Biochim Biophys Acta ; 1857(11): 1786-1795, 2016 11.
Article in English | MEDLINE | ID: mdl-27520074

ABSTRACT

Electrostatic coupling leading to conformational changes in proteins is challenging to demonstrate directly, it requires that both the local, discrete electronic details and dynamic information relevant to the functional descriptions are probed. Here, as a novel study to address this challenge, the roles of an aromatic residue in influencing the functional conformational changes of a membrane receptor in its natural membrane environment are reported. Previously intractable discrete electronic details have been obtained using 2D solid-state NMR of specifically labelled receptor, reinforced with molecular dynamic simulations, mutational analysis and functional assays, supported by and compared with rigid-atom crystal structural models. Hydrogen bonding and hydrophobic interactions are identified as the mechanistic origin for direct electromechanical coupling to the dynamics of conformational changes within the receptor.


Subject(s)
Bacteriorhodopsins/chemistry , Protons , Amino Acid Substitution , Bacteriorhodopsins/genetics , Bacteriorhodopsins/metabolism , Halobacterium/chemistry , Isomerism , Molecular Dynamics Simulation , Protein Conformation , Tyrosine/chemistry , Tyrosine/genetics
9.
Plant J ; 84(2): 347-59, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26332346

ABSTRACT

Glutenin proteins in wheat (Triticum aestivum L.) flour confer unique viscoelastic properties to dough products and, therefore, the concentration and composition of the glutenin proteins determine its end-use value. However, the mechanisms governing the glutenin gene expression remain elusive. In this study, we report that wheat TaGAMyb activates the high-molecular-weight glutenin subunit genes (TaGLU) through recruiting the histone acetyltransferase GCN5. By sequencing the promoters of TaGLU-1 genes from 40 modern wheat cultivars, we identified eight types of TaGAMyb binding motifs and verified these by electrophoretic mobility shift assays. The number of TaGAMyb binding motifs in TaGLU-1 genes is correlated with the abundance of glutenin in different cultivars. Chromatin immunoprecipitation plus polymerase chain reaction (ChIP-PCR) analysis reveals that TaGCN5 directly targets the promoters of TaGLU-1 genes in wheat endosperm. We find that TaGAMyb physically interacts with the wheat histone acetyltransferase TaGCN5 and also interacts with Arabidopsis thaliana AtGCN5. TaGAMyb ectopically expressed in Arabidopsis binds to the TaGLU-1Dy promoter on a TaGLU-1Dy transgene and activates its expression. AtGCN5 also targets the TaGLU-1Dy transgene and is involved in the establishment of acetylation at H3K9 and H3K14. These results demonstrate that TaGAMyb plays a dual role in activating expression of glutenin gene by directly binding to the TaGLU promoter and by recruiting GCN5 to modulate histone acetylation during wheat endosperm development.


Subject(s)
Glutens/metabolism , Histone Acetyltransferases/metabolism , Transcription Factors/metabolism , Triticum/metabolism , Glutens/genetics , Histone Acetyltransferases/genetics , Molecular Weight , Transcription Factors/genetics , Triticum/genetics
10.
Front Plant Sci ; 13: 835164, 2022.
Article in English | MEDLINE | ID: mdl-35646032

ABSTRACT

The area between middle and lower reaches of the Yangtze River is the largest region for soft wheat production in China. In soft wheat breeding, the lack of germplasm with desirable quality for end-use products is a barrier. Ningmai9 is the main variety of soft wheat planted in this area. To create germplasm with better quality and yield potential than Ningmai9, mutants of HMW-GSs in Ningmai9 induced by ethylmethanesulfonate (EMS) were obtained. SDS-PAGE showed that two mutants, md10 and md11, were HMW-GS 1Dy deletions. DNA sequencing confirmed that one mutation was caused by a C/T substitution, resulting in the change of CAA encoding glutamine into the termination codon TAA, and another mutation was due to a G/A substitution in the central repetitive domain of the coding region, causing TGG encoding tryptophan to become the termination codon TGA. The premature termination codon of the 1Dy12 gene affected the expression of 1Dy12 and kept the mRNA at a lower transcription level during the kernel development stage in comparison with the wild type. HMW-GS 1Dy12 deletion mutants decreased the content of HMW-GSs and glutenin macropolymers, mixograph envelope peak time and TIMEX width, water solvent retention capacity (WSRC), and lactic acid solvent retention capacity (LASRC). In the HMW-GS 1Dy12 deletion lines, the sugar-snap cookie diameter was 8.70-8.74 cm, which was significantly larger than that in the wild type of 8.0 cm. There were no significant differences in spike number, kernel number, thousand kernel weight, and yield between the deletion lines and wild type. Overall, the study indicated that the knockout of the HMW-GS gene induced by EMS is an effective way to improve wheat quality, and deletion mutants of HMW-GS 1Dy12 decrease gluten strength and increase sugar snap cookie diameter without yield penalty in Ningmai9 wheat.

11.
Biomed Res Int ; 2022: 9709536, 2022.
Article in English | MEDLINE | ID: mdl-35607303

ABSTRACT

Background: To explore the relationship between sleep time, sleep quality, and emotional and cognitive function in the elderly. Methods: A total of 150 elderly patients over 65 years old who were admitted to our hospital from February 2019 to April 2021 were divided into a normal cognitive function group (Mini-Mental State Examination (MMSE) score: illiteracy, >17; primary school, >20; and middle school and above, >24; N = 86) and cognitive impairment group (MMSE score: illiteracy, ≤17; primary school, ≤20; and middle school or above, ≤24; N = 64). The sleep quality was evaluated by the Pittsburgh Sleep Quality Index (PSQI), and anxiety and depression were evaluated by Hamilton anxiety scale (HAMA) and Hamilton depression scale (HAMD), respectively. The cognitive function between the two groups was compared via the Montreal Cognitive Assessment (MoCA) score, visual spatial execution, and attention. Pearson correlation analysis was used to analyze the correlation between sleep quality, sleep time, and emotional and cognitive function. Results: In the comparison of sleep quality between the two groups, the total score of PSQI, sleep quality, falling asleep time, sleep time, and sleep efficiency of patients with cognitive impairment were higher than those of patients with normal cognitive function (P < 0.05). There was no significant difference in the scores of hypnotic use and daytime dysfunction between the two groups, but the scores of nocturnal sleep disorders and ESS in the cognitive impairment group were significantly higher than those in the normal group (P > 0.05). Compared between the two groups, the MoCA score, visual spatial execution, and attention in the cognitive impairment group were significantly lower than those in the normal group, and the difference was statistically significant (P < 0.05). The delayed recall in the cognitive impairment group was significantly higher than that in the control group (P < 0.05). There was no significant difference in orientation, naming, language, and abstract ability between the two groups (P > 0.05). The scores of HAMA and HAMD in the cognitive impairment group were significantly higher than those in the normal group. Pearson correlation analysis was used to analyze the correlation between sleep therapy, sleep time, and the score of cognitive scale. The results showed that PSQI was negatively correlated with MoCA and MMSE, and ESS was negatively correlated with MoCA and MMSE. Pearson correlation analysis results indicated that PSQI was positively correlated with HAMA and HAMD, while ESS was negatively correlated with HAMA and HAMD. Conclusion: The sleep quality and sleep time of elderly patients are positively correlated with their cognitive function. The worse the sleep quality is, the worse their cognitive function is and the more serious their anxiety and depression are. In the course of clinical therapeutics, more attention should be paid to the sleep quality of elderly.


Subject(s)
Cognitive Dysfunction , Sleep Wake Disorders , Aged , Cognition , Humans , Sleep , Sleep Quality
12.
Scanning ; 2022: 6919130, 2022.
Article in English | MEDLINE | ID: mdl-36016671

ABSTRACT

To analyze the effect of comprehensive nursing intervention based on ERAS's concept in laparoscopic gallbladder polyp (GP) surgery on patients' postoperative quality of life and nursing job satisfaction. Ninety patients with polyps were included in this article until October 2021. In this format, the 45 cases are divided into governing bodies and committees according to their processing time. As recommended by the ERAS committee, the committee provides daily and patient care, as well as training on the WeChat platform. The pain level (visual analogue scale (VAS) score), the quality of life (life quality index (GLQI) score), and the incidence of complications were compared between the two groups before and after the intervention. The VAS score of the control group at 2 h after operation was lower than that of the control group, and the difference was statistically significant (P < 0.05). After the intervention, the GLQI scores of the two groups were higher than those before the intervention, and the GLQI scores of the control group were higher than those of the control group, with significant differences (all P < 0.05). Studies have shown that comprehensive nursing intervention applied to patients with gallbladder polyps can reduce postoperative pain with less complications and can also improve nursing satisfaction, which is worthy of clinical promotion.


Subject(s)
Gallbladder , Quality of Life , Humans , Recovery of Function
13.
Genes (Basel) ; 13(12)2022 12 12.
Article in English | MEDLINE | ID: mdl-36553612

ABSTRACT

The middle to lower reaches of the Yangtze River are China's second largest area for wheat production; wheat disease is more serious there than in other areas because of the high humidity and warm weather. However, most cultivated varieties are susceptible to Fusarium head blight (FHB), powdery mildew, and stripe rust, and the lack of disease-resistant germplasm is an obstacle in wheat breeding. Rye and Thinopyrum elongatum, related species of wheat, carry many genes involved in disease resistance. In this study, a trigeneric hybrid, YZU21, with resistance to FHB, powdery mildew, and stripe rust was used to improve two major wheat cultivars, Ningmai 13 (NM13) and Yangmai 23 (YM23). Specific molecular markers and GISH were used to identify hybrid progenies. Five addition or substitution lines and one translocation line of the Triticum-Secale-Thinopyrum trigeneric hybrid were obtained and evaluated for agronomic traits and the resistance to multiple diseases. The results showed that the six trigeneric hybrid lines had desirable agronomic traits and improved resistance to FHB, powdery mildew, and stripe rust; they might be used as parents in wheat breeding for the resistance to multiple disease.


Subject(s)
Basidiomycota , Fusarium , Triticum/genetics , Secale/genetics , In Situ Hybridization, Fluorescence , Plant Breeding , Chromosomes, Plant , Plant Diseases/genetics , Basidiomycota/genetics , Fusarium/genetics
14.
Medicine (Baltimore) ; 101(35): e30323, 2022 Sep 02.
Article in English | MEDLINE | ID: mdl-36107509

ABSTRACT

RATIONALE: Pancreatic mixed serous neuroendocrine neoplasm (PMSNN) is an extremely rare disease. Only a few cases on the surgical treatment of PMSNN have been reported in the literature, and it is unclear whether there is invasion of important peripancreatic vessels. PATIENT CONCERNS: We report the case of a 39-year-old female patient with PMSNN accompanied by invasion of important peripancreatic vessels. She underwent surgery and achieved satisfactory recovery. DIAGNOSIS: Abdominal enhanced CT images showed an enhanced mass with a nonenhanced cyst involving the head and body of the pancreas, which invaded important peripancreatic vessels. The lesion had been misdiagnosed and mistreated as a metastatic carcinoma before admission. INTERVENTIONS: CT 3-dimensional (3D) visualization reconstruction images showed intact peripancreatic vessels. Radical pancreatoduodenectomy was successfully performed and confirmed that the main blood vessels around the pancreas were only compressed or even wrapped by the mass, but not penetrated. OUTCOMES: The patient recovered well and was discharged on the 19th day after surgery. Pathological examination reported the diagnosis of PMSNN with the collision type combination and the well-differentiated grade 2 pancreatic neuroendocrine tumor. She was followed up for 18 months without any abnormalities. LESSONS: This case demonstrates that surgical treatment of PMSNN with invasion of peripancreatic vessels can be successful. Preoperative abdominal CT 3D visualization reconstruction is helpful in determining the degree of invasion of important peripancreatic vessels, and plays a key role in formulating an accurate surgical plan and improving patient outcome.


Subject(s)
Carcinoma , Pancreatic Neoplasms , Adult , Carcinoma/pathology , Female , Humans , Pancreas/pathology , Pancreatectomy , Pancreatic Neoplasms/diagnostic imaging , Pancreatic Neoplasms/pathology , Pancreatic Neoplasms/surgery , Pancreaticoduodenectomy
15.
World J Clin Cases ; 8(20): 4908-4916, 2020 Oct 26.
Article in English | MEDLINE | ID: mdl-33195660

ABSTRACT

BACKGROUND: The global pandemic of coronavirus disease 2019 pneumonia poses a particular challenge to the emergency surgical treatment of elderly patients with high-risk acute abdominal diseases. Elderly patients are a high-risk group for surgical treatment. If the incarceration of gallstones cannot be relieved, emergency surgery is unavoidable. CASE SUMMARY: We report an 89-year-old male patient with acute gangrenous cholecystitis and septic shock induced by incarcerated cholecystolithiasis. He had several coexisting, high-risk underlying diseases, had a history of radical gastrectomy for gastric cancer, and was taking aspirin before the operation. Nevertheless, he underwent emergency laparoscopic cholecystectomy, with maintenance of postoperative heart and lung function, successfully recovered, and was discharged on day 8 after the operation. CONCLUSION: Emergency surgery for elderly patients with acute abdominal disease is safe and feasible during the coronavirus disease 2019 pandemic, the key is to abide strictly by the hospital's epidemic prevention regulations, fully implement the epidemic prevention procedure for emergency surgery, fully prepare before the operation, accurately perform the operation, and carefully manage the patient postoperatively.

16.
J Agric Food Chem ; 67(42): 11796-11804, 2019 Oct 23.
Article in English | MEDLINE | ID: mdl-31589426

ABSTRACT

High molecular weight glutenin subunits (HMW-GSs) are important components of wheat (Triticum aestivum L.) gluten proteins that affect the processing quality of wheat dough. However, the contributions of individual HMW-GS to sponge cake quality still remain unclear. To investigate the effects of 1Bx7 and 1By9 at Glu-B1 on wheat gluten properties and sponge cake quality, we screened an ethylmethanesulfonate (EMS)-mutagenized wheat population and obtained two independent mutants that lack 1Bx7 and another two mutants that lack 1By9. The absence of 1Bx7 or 1By9 significantly affects the accumulation levels of gluten proteins and the formation of a gluten network. Quality testing indicated that the lack of 1Bx7 or 1By9 leads to weaker dough strength and inferior sponge cake performance. These results demonstrate that 1Bx7 and 1By9 make important contributions to gluten functionality and sponge cake quality.


Subject(s)
Bread/analysis , Glutens/chemistry , Triticum/chemistry , Cooking , Glutens/genetics , Molecular Weight , Protein Subunits/chemistry , Protein Subunits/genetics , Triticum/genetics
17.
Biochim Biophys Acta Bioenerg ; 1859(10): 1006-1014, 2018 Oct.
Article in English | MEDLINE | ID: mdl-29800547

ABSTRACT

Tyrosine 185 (Y185), one of the aromatic residues within the retinal (Ret) chromophore binding pocket in helix F of bacteriorhodopsin (bR), is highly conserved among the microbial rhodopsin family proteins. Many studies have investigated the functions of Y185, but its underlying mechanism during the bR photocycle remains unclear. To address this research gap, in situ two-dimensional (2D) magic-angle spinning (MAS) solid-state NMR (ssNMR) of specifically labelled bR, combined with light-induced transient absorption change measurements, dynamic light scattering (DLS) measurements, titration analysis and site-directed mutagenesis, was used to elucidate the functional roles of Y185 during the bR photocycle in the native membrane environment. Different interaction modes were identified between Y185 and the Ret chromophore in the dark-adapted (inactive) state and M (active) state, indicating that Y185 may serve as a rotamer switch maintaining the protein dynamics, and plays an important role in the efficient proton-pumping mechanism in the bR purple membrane.

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