It has been well-known that VILIP-1 but not VILIP-3 regulates the activity of guanylyl cyclase-B. In order to identify the modulated region within VILIP-1 on regulating guanylyl cyclase-B activity, the recombinant myristoylated and nonmyristoylated VILIPs (VILIP-1, VILIP-3, chimeric VILIPs, and mutant VILIP-1) were prepared in the present study. The recombinant proteins were purified using ion-exchanger chromatography followed by gel filtration. CD spectra indicated that the secondary structure of VILIPs was dominant with £\-helix, reflecting a well-conserved EF-hand structure. Tryptic digestion assay and the fluorescence measurement showed that myristoylation, Ca2+ and Mg2+ differently induced the conformational changes of VILIPs. The results of gel filtration chromatography reflected that the EF-3&4 of VILIP-1 and myristoylation were involved in the dimerization of VILIP-1, and the dimer and monomer were converted each other in a dynamic manner. The porcine brain membrane binding assay and liposome binding assay showed that the binding capability of VILIPs were markedly enhanced by myristoylation, Mg2+ and Ca2+. Myristoylation and the intact EF-1 of VILIP-1 were found to essential for the regulation of guanylyl cyclase activity in the presence of Mg2+ and Ca2+. Taken together, theses results suggest that myristoylation and EF hand-1 of VILIP-1 are the structural elements crucial for regulating the guanylyl cyclase activity. In contrast to oligomerization of VILIP-1, Mg2+ and Ca2+ -induced conformational changes of VILIP-1 and enhancement of the binding of VILIP-1 with membrane by Mg2+ and Ca2+ partly but not heavily involve in the action.

published_or_final_version / Zoology / Master / Master of Philosophy

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2001. / Härtill 5 uppsatser.

Thesis (Ph. D.)--Cornell University, May, 2008. / Vita. Includes bibliographical references (leaves 133-142).

Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 101-111).

Bordetella pertussis produces a number of virulence determinants believed to contribute to its survival in the host as well as to the pathogenesis of disease. One of these factors, adenylate cyclase toxin (ACT), has been implicated to penetrate human neutrophils and macrophages and abrogate their function by virtue of unregulated production of intracellular cAMP. In order to adequately study the nature of ACT and its role in pathogenesis, it is necessary to isolate the toxin from other virulence factors produced by the organism. Attempts by other investigators to purify ACT and maintain both its invasive and catalytic properties have not been successful. B. pertussis produces a cell associated ACT during mid-log phase of growth in Stainer-Scholte medium. Purification of ACT with both activities from urea extracted whole cells has been achieved by hydroxylapatite and calmodulin-sepharose chromatography. ACT is a single protein of 220 kd molecular weight with an isoelectric point of 7.0. The protein probably contains regions which are strongly hydrophobic. ACT has a specific activity of nearly 17,000 μM cAMP formed/min. An 850 ng sample of ACT induced over 1,400 pmoles cAMP/10⁶ S49 mouse lymphoma cells while 660 ng of ACT inhibited human neutrophil chemiluminescence by 65%.

No description available.

Thesis (Ph. D.)--Cornell University, August, 2006. / Vita. Includes bibliographical references (leaves 201-220).

No description available.

Thesis (M.Sc.). / Written for the Dept. of Experimental Medicine. Title from title page of PDF (viewed 2008/05/14). Includes bibliographical references.