Oedema factor, a calmodulin-activated adenylyl cyclase, is important in the pathogenesis of anthrax. Here we report the X-ray structures of oedema factor with and without bound calmodulin. Oedema ...factor shares no significant structural homology with mammalian adenylyl cyclases or other proteins. In the active site, 3'-deoxy-ATP and a single metal ion are well positioned for catalysis with histidine 351 as the catalytic base. This mechanism differs from the mechanism of two-metal-ion catalysis proposed for mammalian adenylyl cyclases. Four discrete regions of oedema factor form a surface that recognizes an extended conformation of calmodulin, which is very different from the collapsed conformation observed in other structures of calmodulin bound to effector peptides. On calmodulin binding, an oedema factor helical domain of relative molecular mass 15,000 undergoes a 15 A translation and a 30 degrees rotation away from the oedema factor catalytic core, which stabilizes a disordered loop and leads to enzyme activation. These allosteric changes provide the first molecular details of how calmodulin modulates one of its targets.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The outer membrane protein complex (BAM complex) plays an important role in outer membrane protein (OMP) assembly in Escherichia coli. The BAM complex includes the integral β‐barrel protein BamA as ...well as four lipoproteins: BamB, BamC, BamD and BamE. One of these lipoproteins, BamD, is essential for the survival of Escherichia coli. The structure of BamD at 2.6 Å resolution shows that this lipoprotein is composed of ten α‐helices that form five tetratricopeptide‐repeat (TPR) motifs. The arrangement of the BamD motifs is similar to that in the periplasmic part of BamA. One of the ten α‐helices, α10, which has been shown to be important for the assembly of the BAM complex, is located in the very C‐terminal region of BamD. A deep groove between TPR domains 4 and 5 is also observed. This groove, as well as the surface around α10, may provide binding sites for other components of the BAM complex. The C‐terminal region of BamD serves as a platform for interactions with other components of the BAM complex. The N‐terminal region shares structural similarity to other proteins whose functions are related to assistance in or regulation of secretion. Therefore, this region is likely to play an important role in the insertion of other outer membrane proteins.
The Japan Sea Rim (JSR) region is the core area for the future sustainable development of Northeast Asia. Effectively assessing the impact of urban expansion on grain production is of great ...significance for achieving sustainable development goals (SDGs), such as SDG2
Zero Hunger
, and promoting sustainable development in Northeast Asia. Only a few studies have assessed the impact of urban expansion on grain production in the JSR. In this study, we initially analyzed urban expansion in the JSR for the period 1992 to 2050. Then, we assessed the impact of urban expansion on cropland net primary productivity (NPP) based on NPP data. Finally, we evaluated the impact of urban expansion on grain production in the JSR. The results indicated that urban land expanded from 21,509 km
2
to 42,501 km
2
in the JSR between 1992 and 2020 (an increase of 1.98 times), and the occupation of cropland caused by urban expansion resulted in a decrease of 2.21 million t in grain production. Urban land will continue to expand from 2020 to 2050, which will cause grain production to decrease by 1.68 (1.02–2.24) million t. China will experience the most serious loss of grain production, accounting for 62.93% (56.69–71.60%) of the total grain production loss in the JSR. Considering the situation for the period 1992–2020, the impact of urban expansion on grain production will be moderated in the future. Thus, the future grain production loss will be reduced by 24.18% (8.80–53.98%). However, future urban expansion will continue to have a negative impact on regional food security. Therefore, we suggest that urban development should be reasonably regulated and high-quality cropland should be protected. Meanwhile, we should strengthen international cooperation and optimize food and economic trade among different countries in the JSR to ensure food security and promote sustainable regional development.
Streptococcus suis, one of the most important and prevalent pathogens in swine, presents a major challenge to global public health. HP0197 is an S. suis surface antigen that was previously identified ...by immunoproteomics and can bind to the host cell surface. Here, we investigated the interaction between HP0197 and the host cell surface glycosaminoglycans (GAGs) using indirect immunofluorescence and cell adhesion inhibition assays. In addition, we determined that a novel 18-kDa domain in the N-terminal region of HP0197 functions as the GAG-binding domain. We then solved the three-dimensional structures of the N-terminal 18-kDa and C-terminal G5 domains using x-ray crystallography. Based on this structural information, the GAG-binding sites in HP0197 were predicted and subsequently verified using site-directed mutagenesis and indirect immunofluorescence. The results indicate that the positively charged residues on the exposed surface of the 18-kDa domain, which are primarily lysines, likely play a critical role in the HP0197-heparin interaction that mediates bacterium-host cell adhesion. Understanding this molecular mechanism may provide a basis for the development of effective drugs and therapeutic strategies for treating streptococcal infections.
Background: The function of the Streptococcus suis antigen HP0197 is unknown, but it may be potentially involved in pathogenesis.
Results: A novel GAG-binding domain on HP0197 was identified, and its structure was determined.
Conclusion: Three clusters of basic residues on an 18-kDa domain of HP0197 are critical for heparin binding and cell adhesion.
Significance: Understanding this mechanism will contribute to the design of drugs to treat streptococcal infections.
The recently described T6SS (type VI secretion system) acts as a needle that punctures the membrane of the target cells to deliver effector proteins. Type VI amidase effectors can be classified into ...four divergent families (Tae1-Tae4). These effectors are secreted into the periplasmic space of neighbouring cells via the T6SS and subsequently rupture peptidoglycan. However, the donor cells are protected from damage because of the presence of their cognate immunity proteins Tai1 (type VI amidase immunity 1)-Tai4. In the present paper, we describe the structure of Tae3 in complex with Tai3. The Tae3-Tai3 complex exists as a stable heterohexamer, which is composed of two Tae3 molecules and two Tai3 homodimers (Tae3-Tai34-Tae3). Tae3 shares a common NlpC/P60 fold, which consists of N-terminal and C-terminal subdomains. Structural analysis indicates that two unique loops around the catalytic cleft adopt a closed conformation, resulting in a narrow and extended groove involved in the binding of the substrate. The inhibition of Tae3 is attributed to the insertion of the Ω-loop (loop of α3-α4) of Tai3 into the catalytic groove. Furthermore, a cell viability assay confirmed that a conserved motif (Gln-Asp-Xaa) in Tai3 members may play a key role in the inhibition process. Taken together, the present study has revealed a novel inhibition mechanism and provides insights into the role played by T6SS in interspecific competition.
Infiltration of rainfall into hillslopes is often an important factor in triggering landslides. Using underground water drainage works together with anti-slide piles has been an effective method of ...landslide control, yet their effectiveness is inadequately discussed in the literature. This paper studies the influence of rainfall on the change in the underground water level beneath a slope by real-time and synchronic monitoring of the rainfall, the underground water level in the boreholes, and the flow rate of the underground drainage tunnel. The effectiveness of the underground drainage tunnel in preventing the rise of the underground water level of the slope is discussed. The researchers also study the deformation behavior of the anti-slide piles by monitoring the lateral displacement of the piles and analyzing the thrust that the anti-slide piles bear by numerical inversion techniques. The results indicate that there is an apparent relationship between the lag in the rising of the underground water level caused by a rainfall and that caused by the immediately previous rainfall. When there is a rainfall accumulation before the occurrence of a heavy rain, this particular heavy rainfall will cause a rapid rise of the underground water level beneath the slope. The monitoring data analysis shows that the flow rate of the underground drainage tunnel increases first, and then the underground water level of the slope rises after a rainfall. In other words, the flow rate of the underground drainage tunnel increases at a rate faster than that of the rise of the underground water level. Hence, the underground drainage tunnel can effectively lower the rise of the underground water level induced by a rainfall. Besides, based on the monitoring data of the lateral displacement of the anti-slide piles and subsequent analysis, the working state of the anti-slide piles is justified. It thus indirectly validates the benefits of using underground drainage tunnel in landslide control.
In Escherichia coli, the BAM complex is essential for the assembly and insertion of outer membrane proteins (OMPs). The BAM complex is comprised of an integral β‐barrel outer membrane protein BamA ...and four accessory lipoproteins BamB, BamC, BamD and BamE. Here, the crystal structure of BamB is reported. The crystal of BamB diffracted to 2.0 Å with one monomer in the asymmetric unit and the structure is composed of eight‐bladed β‐propeller motifs. Pull‐down and Western blotting assays indicate that BamB interacts directly with the POTRA 1–3 domain of BamA and the C‐terminal region of the POTRA 1–3 domain plays an important role in the interaction, while the POTRA 1–2 domain is not required for the interaction.
Structure of human muscle creatine kinase Shen, Yue-quan; Tang, Liang; Zhou, Hai-meng ...
Acta crystallographica. Section D, Biological crystallography,
August 2001, Letnik:
57, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The crystal structure of human muscle creatine kinase has been determined by the molecular‐replacement method and refined at 3.5 Å resolution. The structures of both the monomer and the dimer closely ...resemble those of the other known structures in the creatine kinase family. Two types of dimers, one with a non‐crystallographic twofold symmetry axis and the other with a crystallographic twofold symmetry axis, were found to occur simultaneously in the crystal. These dimers form an infinite `double‐helix'‐like structure along an unusual long crystallographic 31 axis.
Crystal structures of GAPDH from Palinurus versicolor complexed with two coenzyme analogues, SNAD+ and ADP‐ribose, were determined by molecular replacement and refined at medium resolution to ...acceptable crystallographic factors and reasonable stereochemistry. ADP‐ribose in the ADP‐ribose–GAPDH complex adopts a rather extended conformation. The interactions between ADP‐ribose and GAPDH are extensive and in a fashion dissimilar to the coenzyme NAD+. This accounts for the strong inhibiting ability of ADP‐ribose. The conformational changes induced by ADP‐ribose binding are quite different to those induced by NAD+ binding. This presumably explains the non‐cooperative behaviour of the ADP‐ribose binding. Unexpectedly, the SNAD+–GAPDH complex reveals pairwise asymmetry. The asymmetry is significant, including the SNAD+ molecule, active‐site structure and domain motion induced by the coenzyme analogue. In the yellow or red subunits nomenclature of subunits is as in Buehner et al. (1974). J. Mol. Biol.90, 25–49, SNAD+ binds similarly, as does NAD+ in holo‐GAPDH. While, in the green or blue subunit, the SNAD+ binds in a non‐productive manner, resulting in a disordered thionicotinamide ring and rearranged active‐site residues. The conformation seen in the yellow and red subunits of SNAD+–GAPDH is likely to represent the functional state of the enzyme complex in solution and thus accounts for the substrate activity of SNAD+. A novel type of domain motion is observed for the binding of the coenzyme analogues to GAPDH. The possible conformational transitions involved in the coenzyme binding and the important role of the nicotinamide group are discussed.
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