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postgraduate thesis: X-ray crystallographic studies of two virulence factors from two fungal pathogens, P. marneffei and C. neoformans

TitleX-ray crystallographic studies of two virulence factors from two fungal pathogens, P. marneffei and C. neoformans
Authors
Issue Date2012
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Lam, W. [林瑋熙]. (2012). X-ray crystallographic studies of two virulence factors from two fungal pathogens, P. marneffei and C. neoformans. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4961732
AbstractMycoses refer to infections caused by different fungal infections. Some mycoses can be defeated by the hosts themselves attributed to the functional immune systems before severe symptoms appear. However, in immune-compromised patients, including those suffering from AIDS or receiving chemotherapies, those mycoses become lethal. They are called opportunistic systemic mycoses. Among them, two types of the most deadly mycoses, especially for AIDS patients in Southeast Asia, are cryptococcsis and penicillosis, caused by Cryptococcus neoformans (C. neoformans) and Penicillium marneffei (P. marneffei), respectively. Both of them have their own virulence factors to enhance their pathogenicities and survival in hosts. Active research to explore these virulence factors in these two funguses is ongoing. Two proteins from these two pathogens were found to be putative novel virulence factors, MP1p from P. marneffei, and CPL1 from C. neoformans. Collaborators have successfully found that MP1p strongly bound arachidonic acids (AA), the sole precursor of paracrine signaling molecules essential to the onset of inflammatory responses, by various functional studies. This led to the hypothesis that MP1p might be able to suppress inflammatory responses and subsequent immune responses via removal of AA from macrophages engulfed P. marneffei. In this work, X-ray crystal structures of MP1p’s ligand-binding domain 2 (LBD2) from P. marneffei (strain MP1) overexpressed in E. coli, in complex with one and two AA molecules, were successfully solved by molecular replacement method. The resolutions were up to 1.45 Å and 1.50 Å respectively. These structures revealed detailed interactions between MP1p-LBD2 and AA.A possible ligands-dependent dimer-monomer transition in LBD2 was also revealed by both analytical size exclusion chromatography and crystallography. Full length CPL1 overexpressed in yeast was also successfully purified and crystallized. A 3.0 Å native dataset was collected. Heavy atoms derivatives of the crystals would be produced in order to solve the structure via experimental phasing methods. The structural determination of these virulence factors may provide molecular bases at atomic resolution for the developments of drugs targeting MP1p and CPL1 by structure-based drug design to treat, particularly, penicillosis and cryptococcsis in immune-compromised patients.
DegreeMaster of Philosophy
SubjectPathogenic fungi
Penicillium
Mycoses
Cryptococcus
Dept/ProgramPhysiology
Persistent Identifierhttp://hdl.handle.net/10722/193057

 

DC FieldValueLanguage
dc.contributor.authorLam, Wai-hei-
dc.contributor.author林瑋熙-
dc.date.accessioned2013-12-14T10:12:20Z-
dc.date.available2013-12-14T10:12:20Z-
dc.date.issued2012-
dc.identifier.citationLam, W. [林瑋熙]. (2012). X-ray crystallographic studies of two virulence factors from two fungal pathogens, P. marneffei and C. neoformans. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4961732-
dc.identifier.urihttp://hdl.handle.net/10722/193057-
dc.description.abstractMycoses refer to infections caused by different fungal infections. Some mycoses can be defeated by the hosts themselves attributed to the functional immune systems before severe symptoms appear. However, in immune-compromised patients, including those suffering from AIDS or receiving chemotherapies, those mycoses become lethal. They are called opportunistic systemic mycoses. Among them, two types of the most deadly mycoses, especially for AIDS patients in Southeast Asia, are cryptococcsis and penicillosis, caused by Cryptococcus neoformans (C. neoformans) and Penicillium marneffei (P. marneffei), respectively. Both of them have their own virulence factors to enhance their pathogenicities and survival in hosts. Active research to explore these virulence factors in these two funguses is ongoing. Two proteins from these two pathogens were found to be putative novel virulence factors, MP1p from P. marneffei, and CPL1 from C. neoformans. Collaborators have successfully found that MP1p strongly bound arachidonic acids (AA), the sole precursor of paracrine signaling molecules essential to the onset of inflammatory responses, by various functional studies. This led to the hypothesis that MP1p might be able to suppress inflammatory responses and subsequent immune responses via removal of AA from macrophages engulfed P. marneffei. In this work, X-ray crystal structures of MP1p’s ligand-binding domain 2 (LBD2) from P. marneffei (strain MP1) overexpressed in E. coli, in complex with one and two AA molecules, were successfully solved by molecular replacement method. The resolutions were up to 1.45 Å and 1.50 Å respectively. These structures revealed detailed interactions between MP1p-LBD2 and AA.A possible ligands-dependent dimer-monomer transition in LBD2 was also revealed by both analytical size exclusion chromatography and crystallography. Full length CPL1 overexpressed in yeast was also successfully purified and crystallized. A 3.0 Å native dataset was collected. Heavy atoms derivatives of the crystals would be produced in order to solve the structure via experimental phasing methods. The structural determination of these virulence factors may provide molecular bases at atomic resolution for the developments of drugs targeting MP1p and CPL1 by structure-based drug design to treat, particularly, penicillosis and cryptococcsis in immune-compromised patients.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.lcshPathogenic fungi-
dc.subject.lcshPenicillium-
dc.subject.lcshMycoses-
dc.subject.lcshCryptococcus-
dc.titleX-ray crystallographic studies of two virulence factors from two fungal pathogens, P. marneffei and C. neoformans-
dc.typePG_Thesis-
dc.identifier.hkulb4961732-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplinePhysiology-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b4961732-
dc.date.hkucongregation2012-

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