Science, Technology and Engineering

Dear colleagues,

The purpose of this page is to showcase the varied research undertaken by members of the department (or in collaboration with other research groups) that have led to publications in peer-reviewed journals. To highlight your latest publication in this forum, please forward your article details to Dr Fung Lay (HOTP convenor), together with a short (3-4 sentences) summary for the article. We look forward to your contribution.

"publish or perish - publish and flourish"

PLoS Pathog. 2010 Dec 23;6(12):e1001236.

Epstein-Barr virus (EBV) is associated with human malignancies, especially those affecting the B cell compartment such as Burkitt lymphoma. The virally encoded homolog of the mammalian pro-survival protein Bcl-2, BHRF1 contributes to viral infectivity and lymphomagenesis. In addition to the pro-apoptotic BH3-only protein Bim, its key target in lymphoid cells, BHRF1 also binds a selective sub-set of pro-apoptotic proteins (Bid, Puma, Bak) expressed by host cells. A consequence of BHRF1 expression is marked resistance to a range of cytotoxic agents and in particular, we show that its expression renders a mouse model of Burkitt lymphoma untreatable. As current small organic antagonists of Bcl-2 do not target BHRF1, the structures of it in complex with Bim or Bak shown here will be useful to guide efforts to target BHRF1 in EBV-associated malignancies, which are usually associated with poor clinical outcomes.

(Kvansakul M, Wei AH, Fletcher JI, Willis SN, Chen L, Roberts AW, Huang DC, Colman PM)

J Virol. 2010 Dec 15. [Epub ahead of print]

Poxviruses encode numerous proteins that inhibit apoptosis, a form of cell death critical to the elimination of virally infected cells. Sequencing of the deerpox virus genome revealed DPV022, a protein that lacks obvious homology to cellular members of the Bcl-2 family but shares limited regions of amino acid identity with two unique poxviral inhibitors of apoptosis, M11L and F1L. Given the limited homology, we sought to determine whether DPV022 could inhibit apoptosis. Here we show that DPV022 localised to the mitochondria where it inhibited apoptosis. We used a yeast model system to demonstrate that, in the absence of all other Bcl-2 family proteins, DPV022 interacted directly with Bak and Bax. We confirmed the ability of DPV022 to interact with Bak and Bax by immunoprecipitation, and showed that DPV022 prevented apoptosis induced by Bak and Bax over-expression. Moreover, we showed that DPV022 blocked apoptosis even when all the endogenous mammalian anti-apoptotic proteins were neutralised by a combination of selective BH3 ligands. During virus infection, DPV022 interacted with endogenous Bak and Bax and prevented the conformational activation of both. Thus we have characterised a novel poxviral inhibitor of apoptosis with intriguing amino acid differences from the well-studied proteins, M11L and F1L.

(Banadyga L, Lam SC, Okamoto T, Kvansakul M, Huang DC, Barry M)

Blood, First published online: Oct 22 2010. Doi:10.1182/blood-2010-09-303842

Histidine-rich glycoprotein (HRG) is an abundant protein of vertebrate plasma. HRG has been implicated in numerous biological processes such as immune complex/necrotic cell/pathogen clearance, cell adhesion, angiogenesis, coagulation and fibrinolysis. The present review covers the proposed multifunctional roles of HRG with a focus on recent findings that have led to its emergence as a key regulator of immunity and vascular biology. This review also describes for the first time the striking functional similarities between HRG and other important multifunctional proteins found in plasma such as C-reactive protein, mannose binding lectin, C1q, 2 glycoprotein I and thrombospondin-1.

(Ivan K H Poon, Kruti K Patel, David S Davis, Christopher R Parish* and Mark D Hulett*) *Corresponding authors

J Biol Chem. 2010 Sep 22. [Epub ahead of print]

The antifungal activity of the plant defensin NaD1 involves specific interaction with the fungal cell wall, followed by permeabilization of the plasma membrane and entry of NaD1 into the cytoplasm. Prior to this study, the role of membrane permeabilization in the activity of NaD1 as well as the relevance of cell wall binding had not been investigated. To address this, the permeabilization of Fusarium oxysporum f. sp. vasinfectum hyphae by NaD1 was investigated and compared to other antimicrobial peptides including the cecropin-melittin hybrid peptide CP-29, the bovine peptide BMAP-28 and the human peptide LL-37 that are believed to act largely through membrane disruption. NaD1 appeared to permeabilize cells via a novel mechanism that required the presence of the fungal cell wall. NaD1 as well as Bac2A, a linear variant of the bovine peptide bactenecin, were able to enter the cytoplasm of treated hyphae indicating that cell death is accelerated by interaction with intracellular targets.

(van der Weerden NL, Hancock RE, Anderson MA)

Proc Natl Acad Sci U S A. 2010 Aug 24;107(34):15011-5 and 15016-21. Epub 2010 Aug 9

With increased global demand for food crops and biofuels, new research led by Professor Marilyn Anderson and Dr Kerry Dunse has taken an important step towards the next generation of pest resistant plants. Their work, the results of ten years of laboratory and field trials, was published in August in two papers in the Proceedings of the National Academy of Sciences in the USA.

Molecular basis for the resistance of an insect chymotrypsin to a potato type II proteinase inhibitor.
Dunse KM, Kaas Q, Guarino RF, Barton PA, Craik DJ, Anderson MA. Proc Natl Acad Sci U S A. 2010 Aug 24;107(34):15016-21.

Coexpression of potato type I and II proteinase inhibitors gives cotton plants protection against insect damage in the field.
Dunse KM, Stevens JA, Lay FT, Gaspar YM, Heath RL, Anderson MA. Proc Natl Acad Sci U S A. 2010 Aug 24;107(34):15011-5.