BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:MicroCT provides novel insights into plant form and function DTSTART;VALUE=DATE-TIME:20191113T090000Z DTEND;VALUE=DATE-TIME:20191113T092500Z DTSTAMP;VALUE=DATE-TIME:20261008T033939Z UID:indico-contribution-121-2105@events.saip.org.za DESCRIPTION:Speakers: Robert Skelton (University of California Berkeley)\n MicroCT has tremendous potential to provide novel insights into plant form and function My research uses this and other\, novel\, non-invasive optic al techniques to view the process of leaf and stem xylem embolism formatio n within intact plants to resolve long-standing questions in plant physiol ogy. Here\, I will highlight two recent experiments performed at the Austr alian Synchrotron in Melbourne Australia and the Lawrence Berkeley Laborar tory in Berkeley\, California in the USA. We used multiple visual techniqu es\, including X-ray micro- computed tomography and the optical vulnerabil ity method\, to investigate the spread of embolism within intact stems\, l eaves and roots of Solanum lycopersicum (common tomato) and North American oak species. We found that roots\, stems and leaves of tomato plants all exhibited similar vulnerability to embolism\, suggesting that embolism rap idly propagates among tissues. Although we found scarce evidence for diffe rentiation of xylem vulnerability among tissues at the scale of the whole plant\, within a leaf the midrib embolized at higher water potentials than lower order veins. In oaks\, air-entry water potential varied 2-fold in l eaves\, ranging from −1.7 ± 0.25 MPa to −3.74 ± 0.23 MPa\, and 4-fol d in stems\, ranging from −1.17 ± 0.04 MPa to −4.91 ± 0.3 MPa. Embol ism occurred earlier in leaves than in stems in only one out of eight samp le species\, and plants always lost turgor before experiencing stem emboli sm. Our results show that herbaceous species (tomato) and long-vesseled oa k species are more resistant to embolism than previously thought and suppo rt the hypothesis that avoiding stem embolism is a critical component of d rought tolerance in plants.\n\nhttps://events.saip.org.za/event/173/contri butions/2105/ LOCATION: Gold Room URL:https://events.saip.org.za/event/173/contributions/2105/ END:VEVENT BEGIN:VEVENT SUMMARY:Heterologous expression\, crystallization and structural determina tion of Schistosoma mansoni Universal stress G4LZI3 protein by X-ray cryst allography. DTSTART;VALUE=DATE-TIME:20191113T092500Z DTEND;VALUE=DATE-TIME:20191113T095000Z DTSTAMP;VALUE=DATE-TIME:20261008T033939Z UID:indico-contribution-121-2106@events.saip.org.za DESCRIPTION:Speakers: Abidemi Paul Kappo (University of Zululand)\nThe for mation of high quality and perfect crystals forms the bottleneck and rate- limiting step for structure determination by X-ray crystallography. Protei n crystallography has formed an intricate part of the chemical\, biotechno logy and pharmaceutical industry as an important tool towards drug design\ , protein engineering and in understanding various biological systems. In this study\, a Universal stress G4LZI3 protein\, identified as a ‘lead ’ molecule for the design of alternative treatment against schistosomias is\, was subjected to protein crystallization trials. Schistosoma mansoni\ , a parasitic helminth\, is responsible for the neglected tropical disease schistosomiasis that ranks second to malaria in public health significanc e. It accounts for over 280 000 deaths per year and is equally to blame fo r the physical life-long disability and disfigurements associated with the infection with an estimated global prevalence of 200 million. Praziquante l\, which has been the gold standard for treatment for over 3 decades\, ha s now exhibited drug resistance. Over-expression of the G4LZI3 protein thr oughout the schistosome’s lifecycle caused by conditions of stress\, has warranted the need to determine its structure in a bid to design new schi stosomides. The gene sequence coding for the G4LZI3 protein was first clon ed into a pQE-30 vector using BamH1 and HindIII restriction enzymes. The r esultant pQE30-G4LZI3 construct was transformed into M15 bacteria cells. E xpression screening was done to determine the best expressing clone\, and was used for heterologous expression of sufficient amounts of recombinant G4LZI3 protein\, followed by purification on a Ni-NTA column. Thereafter\, the G4LZI3 protein was purified to homogeneity using size exclusion chrom atography\; purified fractions under the chromatogram was pooled together and concentrated down to 10mg/ml\, 15mg/ml\, 17mg/ml\, 20mg/ml and 24mg/ml . These various concentrations were subjected to various crystallization t rials and various conditions yielded considerably sized and 3-dimensional shaped crystals. Complete datasets of 3.5 – 3.99A were collected and mol ecular replacement was achieved using the MR Rosetta software. Coot was us ed to visualize and perform model building on the generated solution. Futu re studies will aim to perform structure-based virtual screening of identi fying small molecule inhibitors that can serve as anti-schistosomals. \nKe ywords: Crystallization\, G4LZI3\, Praziquantel\, gel filtration\, Schisto somiasis\n\nhttps://events.saip.org.za/event/173/contributions/2106/ LOCATION: Gold Room URL:https://events.saip.org.za/event/173/contributions/2106/ END:VEVENT BEGIN:VEVENT SUMMARY:Biophysical characterization of Plasmodium falciparum Hsp70-Hsp90 organizing protein (PfHop) reveals a monomer that is characterised by fold ed segments connected by flexible linkers DTSTART;VALUE=DATE-TIME:20191113T101500Z DTEND;VALUE=DATE-TIME:20191113T104000Z DTSTAMP;VALUE=DATE-TIME:20261008T033939Z UID:indico-contribution-121-2138@events.saip.org.za DESCRIPTION:Speakers: Stanley Makumre (University of Venda)\nPlasmodium fa lciparum causes the most lethal form of malaria. The cooperation of heat s hock protein (Hsp) 70 and 90 is important for the folding of a select numb er of cellular proteins that are crucial for cyto-protection and developme nt of the parasites. Hsp70 and Hsp90 are brought into a functional complex that allows substrate exchange by stress-inducible protein 1 (STI1)\, als o known as Hsp70-Hsp90 organizing protein (Hop). P. falciparum Hop (PfHop) co-localizes and occurs in complex with the parasite cytosolic chaperones \, PfHsp70-1 and PfHsp90. Here\, we characterized the structure of recombi nant PfHop using synchrotron radiation circular dichroism (SRCD) and small -angle X-ray scattering. Structurally\, PfHop is a monomeric\, elongated b ut folded protein\, in agreement with its predicted TPR domain structure. Using SRCD\, we established that PfHop is unstable at temperatures higher than 40 °C. This suggests that PfHop is less stable at elevated temperat ures compared to its functional partner\, PfHsp70-1\, that is reportedly s table at temperatures as high as 80 °C. These findings contribute to our understanding of the role of the Hop-mediated functional partnership betw een Hsp70 and Hsp90.\n\nhttps://events.saip.org.za/event/173/contributions /2138/ LOCATION: Gold Room URL:https://events.saip.org.za/event/173/contributions/2138/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural characterization of neutralizing antibody lineages from an HIV-infected donor DTSTART;VALUE=DATE-TIME:20191113T095000Z DTEND;VALUE=DATE-TIME:20191113T101500Z DTSTAMP;VALUE=DATE-TIME:20261008T033939Z UID:indico-contribution-121-2145@events.saip.org.za DESCRIPTION:Speakers: Thandeka Moyo (National Institute for Communicable D iseases)\nThandeka Moyo1\,2\, Cathrine Scheepers1\, Prudence Kgagudi1\, Ru tendo Ziki1\, Lynn Morris1\, 2\, 3\, Penny L. Moore1\, 2\, 3\n\n1National Institute for Communicable Diseases\, Johannesburg\, South Africa \n2Unive rsity of the Witwatersrand\, Johannesburg\, South Africa \n3Centre for the AIDS Programme of Research in South Africa (CAPRISA)\, Durban\, South Afr ica\n\n\nHIV broadly neutralizing antibody (bNAb) responses develop in chr onic infection in only approximately 25% of HIV-1-infected individuals. Un derstanding how bNAbs develop has been a major focus in HIV vaccine resear ch in recent years. The aim of this study is to solve the structures of co -evolving strain-specific and bNAbs from an HIV-infected donor\, CAP314. W e have recently isolated three antibody lineages from this donor. The firs t lineage is an N332/glycan-dependent lineage which matured from being str ain-specific to broadly neutralizing through the course of infection. Comp arison of early and late antibodies by X-ray crystallography techniques ma y thus provide insight into the differences between the binding of broadly neutralizing and strain-specific antibodies within a single lineage. Prel iminary data suggest the second lineage of interest can be classified as a “helper” lineage which aided in the development of the broad N332/gly can-dependent lineage. Therefore\, using X-ray crystallography to obtain t he structures of these antibodies will aid in understanding how this linea ge shaped viral populations and drove the development of neutralization br eadth. The third lineage identified from this participant recognizes an un defined epitope consisting of elements of both the N332/glycan and the CD4 binding site. Therefore\, solving the structure of this antibody by X-ray crystallography will provide insight into the binding of a neutralizing a ntibody lineage targeting a novel epitope. Collectively\, structural data for three antibody lineages from a single HIV-infected individual represen ts a unique opportunity to investigate the underlying mechanisms used by t he humoral immune response in responding to swarms of HIV variants.\n\nhtt ps://events.saip.org.za/event/173/contributions/2145/ LOCATION: Gold Room URL:https://events.saip.org.za/event/173/contributions/2145/ END:VEVENT END:VCALENDAR