Epithelia acts as barriers to the movement of small molecules, including ions and drugs, between body compartments. Ions cross the epithelial apical and basolateral membranes via tightly regulated ion-specific transporters and channels. However, exogenously supplied drugs, particularly hydrophilic or charged compounds, are not transported to any appreciable extent across the epithelium. Our labooratory has developed 2 different classes of peptides that promote selective ion transport or modulate the epithelial barrier that precludes drug access. The peptide sequences are derived from the pore-forming M2 transmembrane (TM) segment of the spinal cord glycine receptor (M2GlyR). Peptides insert and assemble to form transmembrane structures that display distinct, sequence dependent, physiological responses. They either selectively increase chloride transport or form non-selective channels that transiently facilitate the paracellular movement of larger hydrophilic compounds to the basolateral compartment. The former sequences have been proposed as a possible therapeutic intervention for channelopathies such as cystic fibrosis (CF). The latter are currently under investigation for facilitated transport of hydrophilic antibiotics across the cornea. While much is understood about the channel properties of these sequences in their native context little is understood about the assembled membrane structure(s) of the synthetic peptides. Multi-dimensional solution NMR has been used to investigate the structure of peptide monomers in SDS-micelles and modeling of helical bundles has been attempted. We propose to determine the number of transmembrane segments that assemble to form the active structures in model membranes and cells using both chemical and biophysical methods. Recent studies have indicated that different membrane lipid compositions can alter the secondary structure of these peptides. Studies will be conducted using model membranes with compositions that preseve the helical structure of the peptides. We hypothesize that different sized membrane assemblies could be stabilized in different lipid environments. Knowledge of the the number of segments that assemble under physiological conditions will greatly assist future modeling efforts. Additional experiments are planned that will examine the positioning and hydrogen bonding strength of a ring of threonines at position 17 in the sequences that form anion selective channel pores. Various amino acid substitutions in this position will assess the geometry and hydrogen bonding strengths required to optimize a synthetic channel with regard to selectivity and high throughput. These results will be incorporated into future channel designs with the ultimate goal of defining therapeutic structures.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM074096-01
Application #
6913830
Study Section
Special Emphasis Panel (ZRG1-BMBI (01))
Program Officer
Chin, Jean
Project Start
2005-05-01
Project End
2009-04-30
Budget Start
2005-05-01
Budget End
2006-04-30
Support Year
1
Fiscal Year
2005
Total Cost
$262,800
Indirect Cost
Name
Kansas State University
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
929773554
City
Manhattan
State
KS
Country
United States
Zip Code
66506
Barros, Sheila M; Whitaker, Susan K; Sukthankar, Pinakin et al. (2016) A review of solute encapsulating nanoparticles used as delivery systems with emphasis on branched amphipathic peptide capsules. Arch Biochem Biophys 596:22-42
Avila, L Adriana; Aps, Luana R M M; Sukthankar, Pinakin et al. (2015) Branched amphiphilic cationic oligopeptides form peptiplexes with DNA: a study of their biophysical properties and transfection efficiency. Mol Pharm 12:706-15
Sukthankar, Pinakin; Whitaker, Susan K; Garcia, Macy et al. (2015) Thermally induced conformational transitions in nascent branched amphiphilic peptide capsules. Langmuir 31:2946-55
Chen, Jianhan; Tomich, John M (2014) Free energy analysis of conductivity and charge selectivity of M2GlyR-derived synthetic channels. Biochim Biophys Acta 1838:2319-25
Sukthankar, Pinakin; Avila, L Adriana; Whitaker, Susan K et al. (2014) Branched amphiphilic peptide capsules: cellular uptake and retention of encapsulated solutes. Biochim Biophys Acta 1838:2296-305
Bukovnik, Urska; Sala-Rabanal, Monica; Francis, Simonne et al. (2013) Effect of diaminopropionic acid (Dap) on the biophysical properties of a modified synthetic channel-forming peptide. Mol Pharm 10:3959-66
Sukthankar, Pinakin; Gudlur, Sushanth; Avila, L Adriana et al. (2013) Branched oligopeptides form nanocapsules with lipid vesicle characteristics. Langmuir 29:14648-54
Gao, Jian; Chen, Jianhan (2013) Effects of flanking loops on membrane insertion of transmembrane helices: a role for peptide conformational equilibrium. J Phys Chem B 117:8330-9
Bukovnik, U; Gao, J; Cook, G A et al. (2012) Structural and biophysical properties of a synthetic channel-forming peptide: designing a clinically relevant anion selective pore. Biochim Biophys Acta 1818:1039-48
Zhang, Yuntao; Sukthankar, Pinakin; Tomich, John M et al. (2012) Effect of the synthetic NC-1059 peptide on diffusion of riboflavin across an intact corneal epithelium. Invest Ophthalmol Vis Sci 53:2620-9

Showing the most recent 10 out of 15 publications