Biomedical subjects

Wei Qiao

Publications and source records attributed to Wei Qiao.

6 recordsLinked to original sources

PubMed2006

Zinc metalloregulation of the zinc finger pair domain.

The yeast transcriptional activator Zap1 contains two uncommon structural motifs designated zinc finger pair domains. The hallmark of this domain is the packing of two zinc finger motifs in one globular unit. One finger pair domain in Zap1 contains the AD2 transactivation domain. Zn(II) binding to this domain (ZF1/2) is kinetically labile yielding a zinc-regulated transactivator. The second finger pair domain (ZF3/4) lies within the DNA-binding domain, and it stably binds Zn(II). The goal of this study was to map the determinant conferring lability in Zn(II) binding by using finger pair chimeras. Whereas ZF2 contains the transactivation function, zinc regulation is dependent on the presence of ZF1. ZF3 can functionally replace ZF1, and a ZF3/2 finger pair retains limited zinc regulation. Replacement of ZF3 by ZF1 creating a ZF1/4 chimera was found to stably bind Zn(II), suggesting that the presence of a stable motif (ZF4) can impart binding stability on a labile motif (ZF1). Zn(II) binding in finger pair domains is dependent on the presence of both motifs. Mutations in one finger motif markedly attenuate Zn(II) binding to the second motif. Kinetic lability in Zn(II) binding was mapped to the alpha-helix of ZF2. A ZF1/ZFbeta2alpha4 chimera resembles ZF3/4 in Zn(II) binding stability in incubation studies with the Zn(II) chelators. The present results demonstrate that zinc regulation of AD activity of ZF2 is dependent on determinants in ZF1 as well as the alpha-helix segment of ZF2.

Amino Acid Motifs↗

PubMed2006

Hsc70 contacts helix III of the J domain from polyomavirus T antigens: addressing a dilemma in the chaperone hypothesis of how they release E2F from pRb.

Hsc70's expected binding site on helix II of the J domain of T antigens appears to be blocked in its structure bound to tumor suppressor pRb. We used NMR to map where mammalian Hsc70 binds the J domain of murine polyomavirus T antigens (PyJ). The ATPase domain of Hsc70 unexpectedly has its biggest effects on the NMR peak positions of the C-terminal end of helix III of PyJ. The Hsc70 ATPase domain protects the C-terminal end of helix III of PyJ from an uncharged paramagnetic probe of chelated Gd(III), clearly suggesting the interface. Effects on the conserved HPD loop and helix II of PyJ are smaller. The NMR results are supported by a novel assay of Hsc70's ATP hydrolysis showing that mutations of surface residues in PyJ helix III impair PyJ-dependent stimulation of Hsc70 activity. Evolutionary trace analysis of J domains suggests that helix III usually may join helix II in contributing specificities for cognate hsp70s. Our novel evidence implicating helix III differs from evidence that Escherichia coli DnaK primarily affects helix II and the HPD loop of DnaJ. We find the pRb-binding fragment of E2F1 to be intrinsically unfolded and a good substrate for Hsc70 in vitro. This suggests that E2F1 could be a substrate for Hsc70 recruited by T antigen to an Rb family member. Importantly, our results strengthen the chaperone hypothesis for E2F release from an Rb family member by Hsc70 recruited by large T antigen. That is, it now appears that Hsc70 can freely access helix III and the HPD motif of large T antigen bound to an Rb family member.

Adenosine Triphosphatases↗

PubMed2006

Zinc binding to a regulatory zinc-sensing domain monitored in vivo by using FRET.

We have generated probes of metal binding to zinc fingers (ZFs) that provide tools to study zinc trafficking in vivo. In this study, we used these probes to examine zinc binding by the Zap1 transcription factor of Saccharomyces cerevisiae. Zap1 contains two zinc-regulated activation domains (ADs), AD1 and AD2. AD2 is located within two C2H2 ZFs, ZF1 and ZF2. Studies have indicated that apoAD2 activates transcription and zinc binding to ZF1 and that ZF2 forms an interacting-finger-pair structure that is necessary to inhibit AD function. A related structural finger pair, ZF3 and ZF4, is found in the Zap1 DNA binding domain. In vitro studies indicated that, although the ZF1/2 and ZF3/4 finger pairs bind zinc with similar affinities, zinc that was bound to ZF1/2 was much more labile. We examined the properties of Zap1 ZFs in vivo by FRET. ZF pairs were flanked by enhanced yellow fluorescent protein and enhanced cyan fluorescent protein, allowing detection of zinc-induced conformation changes by FRET. By using these reporters, we found that ZF1/2 and ZF3/4 showed similar responses to zinc under steady-state conditions in vivo. In contrast, ZF1/2 zinc binding was significantly more labile than was ZF3/4. Also, ZF1/2 accumulated in an apo form that could rapidly bind zinc, whereas the ZF3/4 pair did not. Last, we show that these properties are evolutionarily conserved indicating their importance to Zap1 function. These results indicate that the kinetic lability of ZF1/2 in vivo is a key component of Zap1 zinc responsiveness.

Amino Acid Sequence↗

PubMed2006

Curcumin analogs as potent aldose reductase inhibitors.

In the present study, curcuminoids isolated from curcuma longa were demonstrated to possess inhibitory activities on bovine lens aldose reductase. In order to find more potent aldose reductase inhibitor, curcumin analogs were synthesized and evaluated for their ability to inhibit bovine lens aldose reductase enzyme. The results indicated that the compounds with tetrahydroxyl groups, 2,6-bis(3,4-dihydroxybenzylidene)cyclohexanone (A(2)), 2,5-bis(3,4-dihydroxybenzylidene)cyclopentanone (B(2)), 1,5-bis(3,4-dihydroxyphenyl)-1,4-pentadiene-3-one (C(2)), and 3,5-bis(3,4-dihydroxybenzylidene)-4-piperidone (D(2)) showed remarkably potent inhibitory effects on aldose reductase with IC(50) of 2.9 microM, 2.6 microM, 3.4 microM, and 4.9 microM, respectively. The structure-activity relationship revealed that the curcumin analogs with ortho-dihydroxyl groups could form a more tight affinity with aldose reductase to exert more potential inhibitory activities.

Aldehyde Reductase↗

PubMed2006

[Application of ICP-AES to the chemical speciation of heavy metals in flyash].

Chemical speciation of seven heavy metals of flyashes in incinerator was quantitatively tested using ICP-AES. Results showed that ICP-AES procedure could carry out quick, exact and high precision experiments. RSD ratio for most detected metals was lower than 3% while few metals present a comparatively high RSD when whose content was near the detection limits. The recovery ratio was 85.7%-100.63% flyashes were found to have high content of Zn, Pb. Cd, Cu, Mn, Pb and Zn existed mostly as carbonates and were leachable, while Cr and Ni were combined to metal oxides substrates and present immobilization characteristics.

Cadmium↗

PubMedDate not supplied

Hub-based simulation and graphics hardware accelerated visualization for nanotechnology applications.

The Network for Computational Nanotechnology (NCN) has developed a science gateway at nanoHUB.org for nanotechnology education and research. Remote users can browse through online seminars and courses, and launch sophisticated nanotechnology simulation tools, all within their web browser. Simulations are supported by a middleware that can route complex jobs to grid supercomputing resources. But what is truly unique about the middleware is the way that it uses hardware accelerated graphics to support both problem setup and result visualization. This paper describes the design and integration of a remote visualization framework into the nanoHUB for interactive visual analytics of nanotechnology simulations. Our services flexibly handle a variety of nanoscience simulations, render them utilizing graphics hardware acceleration in a scalable manner, and deliver them seamlessly through the middleware to the user. Rendering is done only on-demand, as needed, so each graphics hardware unit can simultaneously support many user sessions. Additionally, a novel node distribution scheme further improves our system's scalability. Our approach is not only efficient but also cost-effective. Only a half-dozen render nodes are anticipated to support hundreds of active tool sessions on the nanoHUB. Moreover, this architecture and visual analytics environment provides capabilities that can serve many areas of scientific simulation and analysis beyond nanotechnology with its ability to interactively analyze and visualize multivariate scalar and vector fields.

Computer Graphics↗