Oldenlandia affinis BAC library construction
In collaboration with:
Dr. Joshua S. Mylne
ARC QEII Fellow
Chemistry & Structural Biology DivisionInstitute for Molecular Bioscience
The University of Queensland
St Lucia, Brisbane, Queensland, 4072, Australia
Phone: +61 7 3346 2021
E-mail: j.mylne@imb.uq.edu.au
Prof. David J. Craik
NHMRC Principal Fellow
Chemistry & Structural Biology DivisionInstitute for Molecular Bioscience
The University of Queensland
St Lucia, Brisbane, Queensland, 4072, Australia
Phone: +61 7 3346 2021
E-mail: d.craik@imb.uq.edu.au
Website :
http://research1t.imb.uq.edu.au/cybase/
Abstract :
Cyclotides are globular plant peptides of around 30 amino acids in size that are held together by a knotted arrangement of three disulfide bonds and possess a cyclised backbone, leaving them with no amino- and carboxy- termini. This combination of a cyclic backbone and cystine knot has been referred to as the cyclic cystine knot (CCK) motif and engenders them with great stability. Cyclotides are cyclised as part of their processing from longer, dedicated precursor proteins that encode one to three mature cyclotides. Any one plant can contain dozens of abundant cyclotides and dozens more that are of lower abundance. Interest in cyclotides has been driven by the array of bioactivities they exhibit, including uterotonic, anti-HIV, anti-neurotensive, cytotoxic, anti-fouling and haemolytic activities. Their biological role in planta, however, is thought to be plant defence, principally insecticidal. Two cyclotides, kalata B1 and kalata B2, have been shown to inhibit the growth and development of Helicoverpa larvae. The toxic effects of kalata B1 are similar to that of the well known Bt toxin. Recent work has shown cyclotides are part of the pre-formed or constitutive plant immune system and show little dynamism to hormonal, abiotic or biotic stimuli. Cyclotides were first discovered in Oldenlandia affinis (Rubiaceae). Its leaves were boiled by women of the Congo region to make a tea that accelerated labour. O. affinis is the model cyclotide plant and to date 21 cyclotides from it have been described. The somatic chromosome number of O. affinis is 2n = 18 (x = 9) and its monoploid genome size is between 4,210 and 4,284 Mbp. While O. affinis dedicates some 5% of its transcriptome to the production of cyclotides, little is known of the arrangement or evolution of cyclotide genes. We will use this BAC library to obtain genomic sequences of cyclotide genes which will provide insights into the mechanism one plant uses to generate such diversity in its cyclotide profile.
Recent publications :
http://www.biomedcentral.com/1471-2164/11/111;
http://onlinelibrary.wiley.com/doi/10.1002/bip.21419/abstract
CNRGV involvement
Responsible : Arnaud Bellec - BAC library construction