RNA and protein in nucleolar structures of dragonfly oocytes

Dragonfly and damselfly oocytes regularly contain two nucleolus like bodies of different sizes, a primary nucleolus and a secondary nucleolus. The primary nucleolus stains more deeply with RNA stains than with an arginine stain; the seconidary nuicleolus stains conzversely. The primary nulcleolus incorporates uridine under all conditions tested; the secondary, only after precautions have been taken to preserve soluble RNA. Both inicorporate lysine.     

The structures of COPI-coated vesicles reveal alternate coatomer conformations and interactions

Transport between compartments of eukaryotic cells is mediated by coated vesicles. The archetypal protein coats COPI, COPII, and clathrin are conserved from yeast to human. Structural studies of COPII and clathrin coats assembled in vitro without membranes suggest that coat components assemble regular cages with the same set of interactions between components. Detailed three-dimensional structures of coated membrane vesicles have not been obtained. Here, we solved the structures of individual COPI-coated membrane vesicles by cryoelectron tomography and subtomogram averaging of in vitro reconstituted budding reactions. The coat protein complex, coatomer, was observed to adopt alternative conformations to change the number of other coatomers with which it interacts and to form vesicles with variable sizes and shapes. This represents a fundamentally different basis for vesicle coat assembly.     

Long-range interactions within a nonnative protein

Protein folding and unfolding are coupled to a range of biological phenomena, from the regulation of cellular activity to the onset of neurodegenerative diseases. Defining the nature of the conformations sampled in nonnative proteins is crucial for understanding the origins of such phenomena. We have used a combination of nuclear magnetic resonance (NMR) spectroscopy and site-directed mutagenesis to study unfolded states of the protein lysozyme. Extensive clusters of hydrophobic structure exist within the wild-type protein even under strongly denaturing conditions. These clusters involve distinct regions of the sequence but are all disrupted by a single point mutation that replaced residue Trp62 with Gly located at the interface of the two major structural domains in the native state. Thus, nativelike structure in the denatured protein is stabilized by the involvement of Trp62 in nonnative and long-range interactions.     

蛋白质与核酸的高级结构预测

对基于分子力学和基于知识的蛋白质高级结构预测方法进行了较详细的评述。介绍了Nussinov碱基最大配对法、Zuker极小自由能法及螺旋区组合类算法等RNA高级结构预测的原理，并对其预测效果进行了评估。此外，还简要论述了基于EST的网络电子克隆技术，并对基于网络的蛋白质与核酸高级结构分析作了概要的介绍。     

Conformational switches modulate protein interactions in peptide antibiotic synthetases

Protein dynamics plays an important role in protein function. Many functionally important motions occur on the microsecond and low millisecond time scale and can be characterized by nuclear magnetic resonance relaxation experiments. We describe the different states of a peptidyl carrier protein (PCP) that play a crucial role in its function as a peptide shuttle in the nonribosomal peptide synthetases of the tyrocidine A system. Both apo-PCP (without the bound 4'-phosphopantetheine cofactor) and holo-PCP exist in two different stable conformations. We show that one of the apo conformations and one of the holo conformations are identical, whereas the two remaining conformations are only detectable by nuclear magnetic resonance spectroscopy in either the apo or holo form. We further demonstrate that this conformational diversity is an essential prerequisite for the directed movement of the 4'-PP cofactor and its interaction with externally acting proteins such as thioesterases and 4'-PP transferase.     

稻米蛋白质的研究进展

综述了国内外有关稻米蛋白质的分子结构、遗传机制、变化机理以及影响蛋白的环境因素、稻米蛋白质研究中常用的测定和提取方法的研究概况，提出目前在高蛋白质含量水稻品种的选育上存在的主要问题及育种新法，为水稻品质育种提供参考。     

水环境中藻类与细菌有益相互作用的研究进展与展望

藻类和细菌在生态系统中重要元素的生物地球化学循环、能量流动等过程中具有重要作用。一些细菌可以通过促进藻类生长、帮助藻类抵抗逆境胁迫等作用,与藻类发生有益相互作用,进而对两者的生存、竞争、生理功能方面均产生重要影响。本文对近年来藻类和细菌有益相互作用的主要方式、微生物类群、分子机制,及其在环境污染处理、生物质能源和合成生物学等方面的应用进展进行综述,并对未来研究提出展望。这不仅对理解水体微生物的群落结构与功能、微生物种间关系的机制与效应具有重要作用,也将为维护生态系统的健康、挖掘和利用生物资源造福人类提供重要的科学依据。     

Agent农业土地变化模型研究进展

农业土地变化是全球变化与可持续研究的热点,当前研究虽取得了长足进展,但仍存在诸多不足,集中表现在对农业土地系统复杂性与动态性的认识不够.近年来,基于Agent的农业土地变化研究(农业ABM/LUCC,Agent-based agricultural land change modeling)逐渐兴起,极大的丰富了传统研究的理论与方法,具体表现在:(1)农业ABM/LUCC将微观层面的人类个体行为整合进土地变化研究框架,有助于更加清楚的认识农业土地系统的“人类-自然”综合复杂性问题.(2)农业ABM/LUCC能够动态表达土地系统变化的内生反馈机制,有助于弥补传统的静态土地变化驱动机制分析的不足.(3)基于ABM/LUCC的农业土地利用格局动态研究是整合“人类-自然”综合研究的关键桥梁,农业ABM/LUCC能够与其他生物地球物理模型或经济模型动态嵌套,使多尺度、多维度综合模型研究成为可能.然而,农业ABM/LUCC研究也存在诸多挑战,如理论研究滞后于应用研究,大尺度应用难以开展,以及农户行为的模拟结果很难得到校验等.     

白桦伸展素蛋白结构分析及同源建模

以白桦伸展素蛋白序列为研究材料,利用生物信息学方法分析该蛋白的氨基酸组成、等电点、疏水/亲水性、跨膜区、二级结构和三级结构等性质,并将其同黑杨、棉花、大豆的伸展素蛋白进行比对和同源分析。结果表明,该蛋白的分子式为C680H1099N195O195S11,为亲水性、不稳定的非跨膜蛋白,主要构件为α-螺旋和无规则卷曲,与黑杨有较高的同源性。     

2C类蛋白磷酸酶的结构与功能研究进展

2C类蛋白磷酸酶(PP2C-type protein phosphatases,PP2C)是一类丝氨酸/ 苏氨酸残基蛋白磷酸酶,在细胞内以单体形式存在,酶催化活性依赖于Mg2 或Mn2 .PP2C通过去磷酸化作用负调控蛋白激酶级联信号系统,参与细胞周期、胁迫信号转导、基因转录、蛋白质翻译及翻译后修饰等细胞活动过程.H2O2、不饱和脂肪酸、Ca2 /CaM、脂质信号分子等均可调节PP2C的活性.     

Probing steric and hydrophobic effects on enzyme-substrate interactions by protein engineering

Steric and hydrophobic effects on substrate specificity were probed by protein engineering of subtilisin. Subtilisin has broad peptidase specificity and contains a large hydrophobic substrate binding cleft. A conserved glycine (Gly(166)), located at the bottom of the substrate binding left, was replaced by 12 nonionic amino acids by the cassette mutagenesis method. Mutant enzymes showed large changes in specificity toward substrates of increasing size and hydrophobicity. In general, the catalytic efficiency (k(cat)/K(m)) toward small hydrophobic substrates was increased (up to 16 times) by hydrophobic substitutions at position 166 in the binding cleft. Exceeding the optimal binding volume of the cleft ( approximately 160 A(3)), by enlarging either the substrate side chain or the side chain at position 166, evoked precipitous drops in catalytic efficiency (k(cat)/K(m)) (up to 5000 times) as a result of steric hindrance.     

蛋白质和脂肪在肥育猪体内的分配沉积规律研究进展

蛋白质和脂肪在肥育猪体内的分配沉积方式与猪的生长性能、产肉性能和肉质性状密切相关.综述了蛋白质和脂肪在肥育猪体内分配沉积规律的研究进展,以期为通过定向调控营养素在肥育猪体内的分配沉积,协调好生长性能和肉质性状的矛盾提供参考.     

Relating three-dimensional structures to protein networks provides evolutionary insights

Most studies of protein networks operate on a high level of abstraction, neglecting structural and chemical aspects of each interaction. Here, we characterize interactions by using atomic-resolution information from three-dimensional protein structures. We find that some previously recognized relationships between network topology and genomic features (e.g., hubs tending to be essential proteins) are actually more reflective of a structural quantity, the number of distinct binding interfaces. Subdividing hubs with respect to this quantity provides insight into their evolutionary rate and indicates that additional mechanisms of network growth are active in evolution (beyond effective preferential attachment through gene duplication).     

Histone H4-K16 acetylation controls chromatin structure and protein interactions

Acetylation of histone H4 on lysine 16 (H4-K16Ac) is a prevalent and reversible posttranslational chromatin modification in eukaryotes. To characterize the structural and functional role of this mark, we used a native chemical ligation strategy to generate histone H4 that was homogeneously acetylated at K16. The incorporation of this modified histone into nucleosomal arrays inhibits the formation of compact 30-nanometer-like fibers and impedes the ability of chromatin to form cross-fiber interactions. H4-K16Ac also inhibits the ability of the adenosine triphosphate-utilizing chromatin assembly and remodeling enzyme ACF to mobilize a mononucleosome, indicating that this single histone modification modulates both higher order chromatin structure and functional interactions between a nonhistone protein and the chromatin fiber.     

蛋白副产物资源开发生物活性肽研究进展

综述了农产品加工中产生的蛋白副产物的主要类型,分析了生物活性蛋白肽的生理功能以及化学方法、物理方法、生物酶法和基因工程等技术手段在蛋白副产物改性中的应用及最新进展,其中生物酶法改性技术易于将蛋白改性到所期望的功能值,是提高蛋白副产物附加值的重要途径,并展望了几种蛋白副产物的开发前景。     

Infection structures from rust urediospores: effect of RNA and protein synthesis inhibitors

Urediospores of Puccinia graminis tritici, floated on buffer, produce infection structures when subjected briefly to 30 degrees C soon after germination. Inhibitors of RNA synthesis interfere with the difierentiation of infection structures if present during this heat treatment. Inhibitors of protein synthesis prevent differentiation if present following heat treatment. Apparently infection structure formation is accompanied by synthesis of RNA, and the completion of infection structure development requires protein synthesis.