This fellowship has three Aims.
The first Aim i s to use the create analogs of the guadinomines through a combined synthetic and biosynthetic approach. Hypothesis-driven analogs will be synthesized, each addressing a question about which structural features are necessary for Type III Secretion System (TTSS) inhibition. Analogs will also be made that should serve as substrates for precursor-directed biosynthesis, which should allow the rapid formation of guadinomine analogs.
The second Aim i s to devise an improved isolation protocol for guadinomines. Natural guadinomines A and B are present at levels of ~1 mg/L of culture media, and require tedious purification procedures. Since guadinomines A and B both contain a vicinal diamine, an uncommon structural subunit, we will exploit its reactivity to enhance its isolation. We have shown that diamines react cleanly with fluorine-containing aldehydes to make aminals at room temperature without added catalysts (May, Khosla - unpublished results). This will allow for solid phase fluorous extraction from the remaining material in the culture media.
The third Aim i s to determine the scope of TTSS inhibition of the guadinomines, and determine how they affect their targets. We have shown that the plant pathogen Xanthomonas is inhibited by guadinomine A (May, Mudgett - unpublished results) and will continue to study plant pathogens with natural guadinomines and their analogs. We will use a Yersinia enterolitica assay to determine which effector proteins, structural proteins, and chaperones are affected by guadinomines. This knowledge will enable a second-generation design of new and more potent analogs.

Public Health Relevance

Pathogenic Gram-negative bacteria use a Type III Secretion System (TTSS) to infect hosts. The goals of the proposal are to study how the guadinomines inhibit TTSS, and to make new and more potent analogs.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32GM099248-03
Application #
8509716
Study Section
Special Emphasis Panel (ZRG1-F04A-G (20))
Program Officer
Barski, Oleg
Project Start
2011-08-01
Project End
2014-07-31
Budget Start
2013-08-01
Budget End
2014-07-31
Support Year
3
Fiscal Year
2013
Total Cost
$53,942
Indirect Cost
Name
Stanford University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305