Substrate Specificity and Plasticity of FERM-Containing Protein Tyrosine Phosphatases

SummaryEpidermal growth factor receptor (EGFR) pathway substrate 15 (Eps15) is a newly identified substrate for protein tyrosine phosphatase N3 (PTPN3), which belongs to the FERM-containing PTP subfamily comprising five members including PTPN3, N4, N13, N14, and N21. We solved the crystal structures of the PTPN3-Eps15 phosphopeptide complex and found that His812 of PTPN3 and Pro850 of Eps15 are responsible for the specific interaction between them. We defined the critical role of the additional residue Tyr676 of PTPN3, which is replaced by Ile939 in PTPN14, in recognition of tyrosine phosphorylated Eps15. The WPD loop necessary for catalysis is present in all members but not PTPN21. We identified that Glu instead of Asp in the WPE loop contributes to the catalytic incapability of PTPN21 due to an extended distance beyond protonation targeting a phosphotyrosine substrate. Together with in vivo validations, our results provide novel insights into the substrate specificity and plasticity of FERM-containing PTPs

Vibration dissipation of an axially traveling string with boundary damping

At present, the control of vibration problem of many engineering equipment can be simplified as a study on transverse vibration of axially traveling string system. In this paper, transverse vibration control and energy dissipation of axially traveling string system is investigated by using a boundary viscous damper. By analyzing the nature frequencies of the fixed length and the variable length of the string system, the resonance frequency of the external concentrated force is obtained. The amplitude and the energy reflection ratio of reflected wave to incident wave is investigated respectively by the force equilibrium principle and the energy equation at the boundary. According to amplitude and the energy reflection ratio, the range and the optimal value of damping coefficient are obtained. The effect of vibration dissipation with a viscous damper and an external concentrated force at the left boundary is investigated respectively by the numerical simulation

SNX27–Retromer directly binds ESCPE-1 to transfer cargo proteins during endosomal recycling

Coat complexes coordinate cargo recognition through cargo adaptors with biogenesis of transport carriers during integral membrane protein trafficking. Here, we combine biochemical, structural, and cellular analyses to establish the mechanistic basis through which SNX27-Retromer, a major endosomal cargo adaptor, couples to the membrane remodeling endosomal SNX-BAR sorting complex for promoting exit 1 (ESCPE-1). In showing that the SNX27 FERM (4.1/ezrin/radixin/moesin) domain directly binds acidic-Asp-Leu-Phe (aDLF) motifs in the SNX1/SNX2 subunits of ESCPE-1, we propose a handover model where SNX27-Retromer captured cargo proteins are transferred into ESCPE-1 transport carriers to promote endosome-to-plasma membrane recycling. By revealing that assembly of the SNX27:Retromer:ESCPE-1 coat evolved in a stepwise manner during early metazoan evolution, likely reflecting the increasing complexity of endosome-to-plasma membrane recycling from the ancestral opisthokont to modern animals, we provide further evidence of the functional diversification of yeast pentameric Retromer in the recycling of hundreds of integral membrane proteins in metazoans

Backbone resonance assignments of the monomeric DUF59 domain of human Fam96a

Proteins containing a domain of unknown function 59 (DUF59) appear to have a variety of physiological functions, ranging from iron-sulfur cluster assembly to DNA repair. DUF59 proteins have been found in bacteria, archaea and eukaryotes, however Fam96a and Fam96b are the only mammalian proteins predicted to contain a DUF59 domain. Fam96a is an 18 kDa protein comprised primarily of a DUF59 domain (residues 31-157) and an N-terminal signal peptide (residues 1-27). Interestingly, the DUF59 domain of Fam96a exists as monomeric and dimeric forms in solution, and X-ray crystallography studies of both forms unexpectedly revealed two different domain-swapped dimer structures. Here we report the backbone resonance assignments and secondary structure of the monomeric form of the 127 residue DUF59 domain of human Fam96a. This study provides the basis for further understanding the structural variability exhibited by Fam96a and the mechanism for domain swapping

Rhamnose Binding Protein as an Anti-Bacterial Agent-Targeting Biofilm of Pseudomonas aeruginosa

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ABL Genomic Editing Sufficiently Abolishes Oncogenesis of Human Chronic Myeloid Leukemia Cells In Vitro and In Vivo

Chronic myelogenous leukemia (CML) is the most common type of leukemia in adults, and more than 90% of CML patients harbor the abnormal Philadelphia chromosome (Ph) that encodes the BCR-ABL oncoprotein. Although the ABL kinase inhibitor (imatinib) has proven to be very effective in achieving high remission rates and improving prognosis, up to 33% of CML patients still cannot achieve an optimal response. Here, we used CRISPR/Cas9 to specifically target the BCR-ABL junction region in K562 cells, resulting in the inhibition of cancer cell growth and oncogenesis. Due to the variety of BCR-ABL junctions in CML patients, we utilized gene editing of the human ABL gene for clinical applications. Using the ABL gene-edited virus in K562 cells, we detected 41.2% indels in ABL sgRNA_2-infected cells. The ABL-edited cells reveled significant suppression of BCR-ABL protein expression and downstream signals, inhibiting cell growth and increasing cell apoptosis. Next, we introduced the ABL gene-edited virus into a systemic K562 leukemia xenograft mouse model, and bioluminescence imaging of the mice showed a significant reduction in the leukemia cell population in ABL-targeted mice, compared to the scramble sgRNA virus-injected mice. In CML cells from clinical samples, infection with the ABL gene-edited virus resulted in more than 30.9% indels and significant cancer cell death. Notably, no off-target effects or bone marrow cell suppression was found using the ABL gene-edited virus, ensuring both user safety and treatment efficacy. This study demonstrated the critical role of the ABL gene in maintaining CML cell survival and tumorigenicity in vitro and in vivo. ABL gene editing-based therapy might provide a potential strategy for imatinib-insensitive or resistant CML patient

بررسی حیطه‌های موجود در فرم‌های ارزشیابی از دیدگاه دانشجویان در دانشگاه علوم پزشکی زنجان در سال تحصیلی 86- 87

زمینه و هدف: ارزشیابی استادان متداول‌ترین روش جهت سنجش کیفیت آموزش می‌باشد. دانشجویان بیش از دست‌اندرکاران در جریان روند آموزش قرار‌دارند بنابراین با نظرخواهی از آنان دیدگاه کاملی برای مسئولین در مورد نقاط قوت و ضعف استادان به‌دست می‌آید. هدف از این پژوهش بررسی حیطه‌های موجود در فرم‌های ارزشیابی از دیدگاه دانشجویان در دانشکده‌های پزشکی، پیراپزشکی و پرستاری و مامایی می‌باشد. روش بررسی: این تحقیق به صورت توصیفی انجام گرفت. 1683 برگ ارزشیابی دانشجویان از استادان هیأت علمی (73 نفر) مربوط به دانشکده‌های پزشکی، پیراپزشکی و پرستاری- مامایی بررسی شد. پرسش‌نامه‌ی دانشجویان پزشکی حاوی 15 سؤوال و دانشجویان پیراپزشکی و پرستاری مامایی 21 سؤوال بود که بر اساس مقیاس لیکرات از حیطه‌های مختلف مقرراتی، علمی و آموزشی، نظارتی و نگرشی تشکیل شده بود. نمرات سؤوالات از نمره‌ی 100 محاسبه شد، نمرات بالاتر بیانگر عملکرد مطلوب‌تراستادان می‌باشد. تجزیه و تحلیل داده‌ها به‌صورت آمار توصیفی با نرم‌افزار SPSS انجام شد. یافته‌ها: نتایج نشان داد مقایسه در سطوح کلی بین دانشکده‌ها، دانشکده‌ی پیراپزشکی با میانگین کل و انحراف معیار 61/3 ±50/85 نسبت به سایر دانشکده‌ها برتری دارد. دانشکده‌ی پیراپزشکی در حیطه‌ی مقرراتی با میانگین و انحراف معیار 89/3±01/91، دانشکده‌ی پزشکی در حیطه‌ی نگرشی با میانگین و انحراف معیار 45/5±48/90 و دانشکده‌ی پرستاری مامایی در حیطه‌ی مقرراتی با میانگین و انحراف معیار 25/4±34/88 بیشترین امتیاز را داشتند. نتیجه‌نهایی نشان می‌دهد، حیطه‌ی علمی و آموزشی نسبت به سایر حیطه‌ها در سطح پایین‌تر می‌باشد. نتایج حیطه‌ها (علمی و آموزشی، نظارتی و نگرشی) بین دانشکده‌ها معنی‌دار می‌باشد (0001/0=P). نتیجه‌گیری: به نظر می‌رسد با برنامه‌ریزی جهت برگزاری کارگاه‌های آموزشی، روش تدریس و تحقیق جهت ارتقای آموزش استادان، اعطا‌ی فرصت مطالعاتی و تشویق انجام کارهای تحقیقاتی و پژوهشی گام مؤثری جهت ارتقای سطح علمی و بالاخره عملکرد بالای استادان خواهد بود

The 1.2 A resolution crystal structure of TcpG, the Vibrio cholerae DsbA disulfide-forming protein required for pilus and cholera-toxin production

The enzyme TcpG is a periplasmic protein produced by the Gram-negative pathogen Vibrio cholerae. TcpG is essential for the production of ToxR-regulated proteins, including virulence-factor pilus proteins and cholera toxin, and is therefore a target for the development of a new class of anti-virulence drugs. Here, the 1.2 Å resolution crystal structure of TcpG is reported using a cryocooled crystal. This structure is compared with a previous crystal structure determined at 2.1 Å resolution from data measured at room temperature. The new crystal structure is the first DsbA crystal structure to be solved at a sufficiently high resolution to allow the inclusion of refined H atoms in the model. The redox properties of TcpG are also reported, allowing comparison of its oxidoreductase activity with those of other DSB proteins. One of the defining features of the Escherichia coli DsbA enzyme is its destabilizing disulfide, and this is also present in TcpG. The data presented here provide new insights into the structure and redox properties of this enzyme, showing that the binding mode identified between E. coli DsbB and DsbA is likely to be conserved in TcpG and that the [beta]5-[alpha]7 loop near the proposed DsbB binding site is flexible, and suggesting that the tense oxidized conformation of TcpG may be the consequence of a short contact at the active site that is induced by disulfide formation and is relieved by reduction