The purpose of the proposed research is to investigate basic mechanisms of activation of the human alternative pathway and to learn in molecular detail how the proteins recognize potential pathogens and distinguish them from host cells and tissues. The work addresses four questions central to the biological functions of the pathway. First, how does factor H recognize human cells and tissues and protect them from damage by the continuously activating alternative pathway. Work will focus on the recently described site on factor H centered on the 13th SCR domain which interacts with polyanions prevalent on human cells and tissues. Site-directed mutagenesis of this site will be guided by the NMR-derived structure of SCR domains and the mutagenized proteins will be expressed and examined for functional changes. Second, discrimination between weak and strong activators (i.e. nonvirulent and virulent organisms) is not well understood, but is medically important. Two sites on C3b have been identified which appear to regulate the rate and extent of activation. The specificity and structure of these sites will be examined. Third, the mechanism of thioester reformation following scission of the thioester by ammonia will be investigated. A conformational intermediate has been trapped at low temperature which can refold at higher temperatures to give native C3 with spontaneous thioester reformation between Cys-988 and Gln-991. Experiments are proposed to reveal the chemistry involved, the energy requirements and the presence of similar conformational intermediates for C4 and alpha2M. Fourth, little is known about the structure and function of the C5 convertase of the alternative pathway. Because a widely accepted theory about the structure of C5 convertases has recently been disproven and almost nothing is known about its catalytic activity, the structure and function of this critical enzyme will be investigated.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37DK035081-16
Application #
6164517
Study Section
Special Emphasis Panel (NSS)
Program Officer
Badman, David G
Project Start
1984-09-01
Project End
2002-02-28
Budget Start
2000-03-01
Budget End
2002-02-28
Support Year
16
Fiscal Year
2000
Total Cost
$205,787
Indirect Cost
Name
University of Texas Health Center at Tyler
Department
Biochemistry
Type
Other Domestic Higher Education
DUNS #
City
Tyler
State
TX
Country
United States
Zip Code
75708
Ferreira, Viviana P; Fazito Vale, Vladimir; Pangburn, Michael K et al. (2016) SALO, a novel classical pathway complement inhibitor from saliva of the sand fly Lutzomyia longipalpis. Sci Rep 6:19300
Takeda, Katsuyuki; Thurman, Joshua M; Tomlinson, Stephen et al. (2012) The critical role of complement alternative pathway regulator factor H in allergen-induced airway hyperresponsiveness and inflammation. J Immunol 188:661-7
Cortes, Claudio; Ferreira, V P; Pangburn, Michael K (2011) Native properdin binds to Chlamydia pneumoniae and promotes complement activation. Infect Immun 79:724-31
Renner, Brandon; Ferreira, Viviana P; Cortes, Claudio et al. (2011) Binding of factor H to tubular epithelial cells limits interstitial complement activation in ischemic injury. Kidney Int 80:165-73
Ferreira, Viviana P; Pangburn, Michael K; Cortes, Claudio (2010) Complement control protein factor H: the good, the bad, and the inadequate. Mol Immunol 47:2187-97
Renner, Brandon; Coleman, Kathrin; Goldberg, Ryan et al. (2010) The complement inhibitors Crry and factor H are critical for preventing autologous complement activation on renal tubular epithelial cells. J Immunol 185:3086-94
Rohrer, Bärbel; Long, Qin; Coughlin, Beth et al. (2010) A targeted inhibitor of the complement alternative pathway reduces RPE injury and angiogenesis in models of age-related macular degeneration. Adv Exp Med Biol 703:137-49
Agarwal, Sarika; Ferreira, Viviana P; Cortes, Claudio et al. (2010) An evaluation of the role of properdin in alternative pathway activation on Neisseria meningitidis and Neisseria gonorrhoeae. J Immunol 185:507-16
Ferreira, Viviana P; Cortes, Claudio; Pangburn, Michael K (2010) Native polymeric forms of properdin selectively bind to targets and promote activation of the alternative pathway of complement. Immunobiology 215:932-40
Thurman, Joshua M; Renner, Brandon; Kunchithapautham, Kannan et al. (2010) Aseptic injury to epithelial cells alters cell surface complement regulation in a tissue specific fashion. Adv Exp Med Biol 664:151-8

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