Article

A transmembrane segment mimic derived from Escherichia coli diacylglycerol kinase inhibits protein activity.

Division of Structural Biology and Biochemistry, Research Institute, Hospital for Sick Children, 555 university Avenue, Toronto, Ontario M5G 1X8, Canada.
Journal of Biological Chemistry (impact factor: 4.77). 07/2003; 278(24):22056-60. DOI:10.1074/jbc.M210685200 pp.22056-60
Source: PubMed

ABSTRACT The function of membrane proteins is inextricably linked to the proper packing and assembly of their independently helical transmembrane (TM) segments. Here we examined whether an externally added TM peptide analogue could specifically inhibit the function of the membrane protein from which it is derived by competing for native TM helix packing sites, thereby producing a non-functional peptide-protein complex. This hypothesis was tested using Lys-tagged peptides synthesized with sequences corresponding to the three TM segments of the homotrimeric Escherichia coli diacylglycerol kinase (DGK). The peptide corresponding to wild-type DGK TM-2 inhibited the protein's enzymatic activity in a dose-dependent manner through formation of an inactive pseudo-complex, whereas peptides derived from TM-1 and TM-3 were benign toward DGK structure/function. Also, substitution of a conserved residue (Glu-69) within the TM-2 peptide abolished these effects, demonstrating the strict sequence requirements for TM-2-mediated association. This strategy, coupled with the practical advantages of the water solubility of Lys-tagged TM peptides, may constitute an attractive approach for the design of therapeutic membrane protein modulators even in the absence of a high resolution structure.

0 0
 · 
0 Bookmarks
 · 
16 Views
  • Source
    Article: Transmembrane inhibitors of P-glycoprotein, an ABC transporter.
    Nadya I Tarasova, Rishi Seth, Sergey G Tarasov, Teresa Kosakowska-Cholody, Christine A Hrycyna, Michael M Gottesman, Christopher J Michejda
    [show abstract] [hide abstract]
    ABSTRACT: Drug resistance mediated by ABC transporters such as P-glycoprotein (P-gp) continues to be a major impediment to effective cancer chemotherapy. We have developed a panel of highly specific peptide inhibitors of P-gp based on the structure of the transmembrane domains of the transporter. These peptides are thought to exert their inhibitory action by disrupting the proper assembly of P-gp. A novel 96-well-plate assay based on the efflux of fluorescent P-gp substrate DiOC2 (3-ethyl-2-[3-(3-ethyl-2(3H)-benzoxazolylidene)-1-propenyl]benzoxazolium iodide) was developed and used for structure-functional characterization of transporter inhibitors. The studies strongly suggest that potent and selective inhibitors of ABC transporters can now be developed solely on the basis of the primary structures of the target proteins. The inhibition of P-gp with transmembrane peptides was shown to be chirality-independent. A 25-residue long retroinverso D-analogue of transmembrane domain 5 inhibited the efflux of the fluorescent P-gp substrate with an IC50 of 500 nM. Transmembrane peptides effectively sensitized resistant cancer cells to doxorubicin in vitro without demonstrating any cell toxicity of their own. The newly synthesized P-gp antagonists appear to be promising nontoxic drug resistance inhibitors that merit further development.
    Journal of Medicinal Chemistry 07/2005; 48(11):3768-75. · 5.25 Impact Factor
  • Source
    Article: Structural plasticity of a transmembrane peptide allows self-assembly into biologically active nanoparticles.
    Sergey G Tarasov, Vadim Gaponenko, O M Zack Howard, Yuhong Chen, Joost J Oppenheim, Marzena A Dyba, Sriram Subramaniam, Youngshim Lee, Christopher Michejda, Nadya I Tarasova
    [show abstract] [hide abstract]
    ABSTRACT: Significant efforts have been devoted to the development of nanoparticular delivering systems targeting tumors. However, clinical application of nanoparticles is hampered by insufficient size homogeneity, difficulties in reproducible synthesis and manufacturing, frequent high uptake in the liver, systemic toxicity of the carriers (particularly for inorganic nanoparticles), and insufficient selectivity for tumor cells. We have found that properly modified synthetic analogs of transmembrane domains of membrane proteins can self-assemble into remarkably uniform spherical nanoparticles with innate biological activity. Self-assembly is driven by a structural transition of the peptide that adopts predominantly a beta-hairpin conformation in aqueous solutions, but folds into an alpha-helix upon spontaneous fusion of the nanoparticles with cell membrane. A 24-amino acid peptide corresponding to the second transmembrane helix of the CXCR4 forms self-assembled particles that inhibit CXCR4 function in vitro and hamper CXCR4-dependent tumor metastasis in vivo. Furthermore, such nanoparticles can encapsulate hydrophobic drugs, thus providing a delivery system with the potential for dual biological activity.
    Proceedings of the National Academy of Sciences 06/2011; 108(24):9798-803. · 9.68 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

DGK structure/function
 
dose-dependent manner
 
externally added TM peptide analogue
 
helical transmembrane
 
inactive pseudo-complex
 
Lys-tagged peptides synthesized
 
Lys-tagged TM peptides
 
membrane proteins
 
native TM helix
 
non-functional peptide-protein complex
 
practical advantages
 
resolution structure
 
sequences corresponding
 
strict sequence requirements
 
therapeutic membrane protein modulators
 
three TM segments
 
TM-2 peptide
 
TM-2-mediated association
 
water solubility
 
wild-type DGK TM-2 inhibited